New option for fuel pump replacement

[VetteMed]

So, with my recent saga of the drop-in pump/sender replacement from the partsladi on ebay (made in china, primary pump failed two months/100 miles after installation, partsladi not willing to refund/replace without original box), I figured I'd look for another option. It's well known that the replacement fuel pumps for a '96 Suburban 2500 with 454 is a drop-in replacement.

Bosch recently introduced a line of "turbine" fuel pumps which are supposed to reduce noise, vibration, and fuel line pulsation. Apparently, the conventional roller-vane or gear rotor pumps actually feed fuel in "pulses" rather than a continuous flow pattern, resulting in the need for a "pulsator" in the fuel line, to smooth out the up-down variation in flow. These turbine pumps apparently feed fuel linearly, and therefore there's no pulsation. These pumps also carry a lifetime warranty (I think through Bosch, though I bought it at Advance Auto and that's where I saw the lifetime warranty mentioned). After being stranded once, I like the idea of being able to exchange the pump at any advance auto store, if it happens again.

The Turbine pump that is a replacement for the Suburban is part number 69225.

-- To access the fuel pumps, the filler door assembly has to be removed. Lift the fuel filler door, then remove four Torx-head screws which secure the door assembly to the body. Lift door assembly off car.

-- Unscrew the fuel filler cap.

-- Gently remove rubber boot around filler neck. These are hard to find, so try not to tear it if yours is brittle.

-- There are 3 hose connections - supply, return, and vapor. All must be disconnected. The rubber will probably be stuck on to the metal fittings, you can gently use a pliers with a rag in the jaws, to twist the rubber off of the metal, after removing the clamp(s). To prevent fuel leakage, use a clean bolt that fits snugly in the supply and return lines.

-- There's one wiring connector - unplug it.

-- There are 8-10 10mm bolts that secure the pump assembly flange to the mounting location on the tank.

-- Once all wiring, plumbing, and bolts are removed, the pump assembly can be lifted up a bit. As you lift it up, you'll need to rotate it 90 degrees to maneuver it out of the filler hole. It takes some trial and error to get the right angle, more so when re-installing.

-- Once the assembly is out of the tank, you can use a wire cutter to snip the zip-ties that secure the pumps in place.


I went to the store with the "correct" chinese Delco pumps, and had the counter person measure them with a caliper. The Bosch 69225 is marginally wider - I think it was a few mm wider, but I figured there's enough play in the assembly that maybe it'd fit.

Apparently, it's just shy of fitting. The pump fits 3/4 of the way into position before getting stuck in the plastic housing cylinder. As a result, it's impossible to fit the strainer sock on the intake of the pumps.

Here's a pic of how far the new pump fits into the housing, with no modifications:
http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1609.jpg

It looks good, but it's about 1/4 to 1/2 inch shy of being fully seated.

So, what I did, was whip out the Dremel with a cut-off wheel, and cut a relief slit in the side of the plastic housing cylinders. I was careful to not extend this to the bottom cup of each cylinder, in order to avoid sacrificing too much strength.

http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1617.jpg

This allowed the cylinder to expand just enough to seat the pump fully. Once seated, the strainer sock could be fitted without a problem, and the factory zip-tie retention method could be duplicated.

http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1619.jpg

More to come in next post...

[VetteMed]

The Bosch pumps include an adapter harness to convert the factory narrow plug to the wider socket of the Bosch pump. This allows the option of returning to an OEM pump without too much headache, other than the presence of the relief slits, which I don't think should present a problem.

http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1621.jpg
http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1623.jpg

Harness adapter installed:
http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1620.jpg

Interestingly, the 2 new 69225 pumps had the same part number, but one had a green top, the other black. Probably just different lots or production times, I guess.

I replaced all of the cheesy stock black plastic clamps with proper metal clamps (the bosch pumps each come with 4 metal band clamps).
http://i680.photobucket.com/albums/vv163/agchoset/fuel%20pump/IMG_1625.jpg

-- If the original strainer socks are in good condition, they can be reused. Aftermarket replacements are available (and required for Bosch's warranty on the pumps). The only difference is that the aftermarket strainer socks don't utilize the factory method for securing the free end to the pump holder. I don't see this as a big issue, as the strainer's press-fit on to the intake of the pump seems very secure.

[4DSZR1]

Good pictures and write-up.

Question, Did you dremel in two slits? And did the Bosch pump make it any more difficult to get the unit back in the tank?

Thanks

Rick

[VetteMed]

Good pictures and write-up.

Question, Did you dremel in two slits? And did the Bosch pump make it any more difficult to get the unit back in the tank?

Thanks

Rick

I dremeled just one longitudinal slit into each cylinder. It was just a matter of giving another millimeter or two for clearance, without sacrificing much strength. I had no additional difficulty in replacing the assembly into the tank.

Thanks
Andrew

[secondchance]

Thanks for a great alternative!
My pumps are good so far (knock on wood...) but if I need replacement I will try this route.

[tomtom72]

Thanks for posting this fix!:thumbsup:

It kind of stinks that the P/Laddie seems to be inflexible on the warr issue. I mean where else would we all buy ZR-1 pump assemblies from????:rolleyes:

I also bought one of those assemblies from Laddie because of the great price. Looks like I should have gone another route. I figured plug & play was consistent with the KISS school of thought. I guess it's too much to think that the parts would have good Q/Control.:(

[4DSZR1]

Thanks for the reply Andrew

Looks like the best fix yet.

[4DSZR1]

woops, One more question Andrew, please.... How do you know when the bosch pump is filly seated in the housing?

Thanks again

Rick

[VetteMed]

woops, One more question Andrew, please.... How do you know when the bosch pump is filly seated in the housing?

Thanks again

Rick

Easiest way to tell is that the neck that the strainer sock fits on to extends beyond the bottom of the housing. Otherwise, you can't put the sock on correctly. If the sock fits, you're in good shape! :thumbsup:

[HAWAIIZR-1]

Thanks for sharing the info. I bought one of these too to keep for the day I need it. By then the warranty will be over and wasted $. I don't know if they will refund and I have the original box.

[VetteMed]

Just took it for a test drive, ran up to 7K in 4th gear a few times, everything seems to be working well! It's probably just my imagination that makes it feel faster than before, but I'm not complaining!

[4DSZR1]

:thumbsup:


Thanks for all the detail on this.

Rick

[tomtom72]

Just took it for a test drive, ran up to 7K in 4th gear a few times, everything seems to be working well! It's probably just my imagination that makes it feel faster than before, but I'm not complaining!

New parts, like new oil & coolant, always makes the car run better!:mrgreen:

:cheers:

[secondchance]

New parts, like new oil & coolant, always makes the car run better!:mrgreen:

:cheers:

Fresh wax always makes car run faster for real - less aerodynamic drag.
Similar to placebo effect?

[TFENT]

A few questions here.

Did you need a new gasket for the sender assembly?

What is the part # or application for the new sock?

Is there anything else you need to buy before diving into a pump replacement?

TY :)

[VetteMed]

A few questions here.

Did you need a new gasket for the sender assembly?

What is the part # or application for the new sock?

Is there anything else you need to buy before diving into a pump replacement?

TY :)

The gasket should be a reusable flat rubber seal. I am not sure if it's available as its own part no.

The sock is the same as stock, the nipple on the pump is the same standard size. Any parts store will be able to set you up with an appropriate sock.

Nothing else to buy - as long as you have a way to cut the relief slots in the pump holder, and a few zip ties on hand to secure them once finished.

[dallas]

The gasket should be a reusable flat rubber seal. I am not sure if it's available as its own part no.

The sock is the same as stock, the nipple on the pump is the same standard size. Any parts store will be able to set you up with an appropriate sock.

Nothing else to buy - as long as you have a way to cut the relief slots in the pump holder, and a few zip ties on hand to secure them once finished.

The zip ties to put around the slotted cover to hold it tight???

[TFENT]

I called a resource and a whole new AC Delco sending unit with 2 Delphi pumps is only $275. I am thinking of just getting the new unit...

Thoughts???

[VetteMed]

The zip ties to put around the slotted cover to hold it tight???

Correct, the zip ties are the factory method for retaining the pump within the cylindrical housing. There are slots at the top of each housing, for routing the zip ties through.

[VetteMed]

I called a resource and a whole new AC Delco sending unit with 2 Delphi pumps is only $275. I am thinking of just getting the new unit...

Thoughts???

That's the easier approach, for sure... and you get a new sending unit with it. I went the Bosch route because my faith in the reliability of some of the so-called ACDelco pumps was shaken by my bad experience. Others have had better luck...

[TFENT]

That's the easier approach, for sure... and you get a new sending unit with it. I went the Bosch route because my faith in the reliability of some of the so-called ACDelco pumps was shaken by my bad experience. Others have had better luck...

What are the concerns with the AC Delco pumps?

[VetteMed]

http://zr1.net/forum/showthread.php?t=9763&page=2

That should explain a little... some folks get pretty heated and defensive when I bring up the issue, but when you are buying so-called ACDelco parts, it's best to check on the return policy beforehand... there's lots of "white box" parts out there, some may be legitimate ACDelco parts, but I have my doubts about some. The vendor in question in my case was Partsladi on ebay, who is no longer in business...:dancing

[TFENT]

http://zr1.net/forum/showthread.php?t=9763&page=2

That should explain a little... some folks get pretty heated and defensive when I bring up the issue, but when you are buying so-called ACDelco parts, it's best to check on the return policy beforehand... there's lots of "white box" parts out there, some may be legitimate ACDelco parts, but I have my doubts about some. The vendor in question in my case was Partsladi on ebay, who is no longer in business...:dancing

This is from a GM dealership and is a genuine AC Delco part. Is there some concern with this part??

[VetteMed]

Probably not, but....:dontknow:

This is from a GM dealership and is a genuine AC Delco part. Is there some concern with this part??

[TFENT]

Probably not, but....:dontknow:

So basically just make sure its NOT made in China right??

Bottom line for me here is when I crack open the tank and take the old unit out and its covered in rust I want to replace it with a new unit. I just dont know what I am going to find. Car is a 1990 with 32K on it. been sitting around a longgggggg time.

[VetteMed]

So basically just make sure its NOT made in China right??

Bottom line for me here is when I crack open the tank and take the old unit out and its covered in rust I want to replace it with a new unit. I just dont know what I am going to find. Car is a 1990 with 32K on it. been sitting around a longgggggg time.

There's plenty of legitimate Delco parts being made in China nowadays. There's no guarantees on quality... but at least with a proper return policy / warranty you may sleep a little better at night. The Bosch pumps are made in Brazil, FWIW.

[Blue Flame Restorations]

Did the same fuel pump install today. Very easy to cut the relief in the holster. Used the same Bosch 69225 pumps. Runs great.

NOTE:

AIRTEX fuel pumps suck. Lasted about a month. Lesson learned......

[VetteMed]

Good stuff, Brett!

[Blue Flame Restorations]

Thanks for your write-up on this option. Really appreciate it.:cheers:

[VetteMed]

Thanks for your write-up on this option. Really appreciate it.:cheers:

Glad it helped you! :handshak:

[scottfab]

I called a resource and a whole new AC Delco sending unit with 2 Delphi pumps is only $275. I am thinking of just getting the new unit...

Thoughts???

Not a bad idea. Having one whole assembly as a spare is what I'm thinking now. I'd worry about all the mods cracking and falling apart and/or multiple splices adding to intermittent issues. And yet this could be a good alternative should it hold up for a few years.

[Blue Flame Restorations]

The modification to the fuel pump holsters was a simple relief cut and will not compromise the ability to hold the pumps. The holsters will outlast the pumps. No problem.

NOTE: The relief cut is not the entire length of the holster. I only cut it near the bottom where the pump would not fully seat.

[VetteMed]

The modification to the fuel pump holsters was a simple relief cut and will not compromise the ability to hold the pumps. The holsters will outlast the pumps. No problem.

My thoughts exactly. Much ado about nothing.

[tomtom72]

I did this "mod" at 17 yrs and about 33k miles. My OE pumps were just a bit tired showing on the low side of the FSM PSI spec spread. I now have 55k miles so figure about 22k miles and 5 yrs worth of use, and the only issue I have had was one of the factory plastic clamps cracked. The holders for the pumps are in great condition as I just looked at them the other day when I pulled it out to check the screw clamps I used to replace the OE plastic clamps.

I know this sounds a bit stupid, but I could actually feel the difference from my original BG pumps and the new ones when I get into the secondaries. My OEM pumps tested right at 46 PSI with the KOEO test, now the Bosch pumps still test at 55 - 54 PSI.

I should mention this as a fwiw. When I bought the Bosch pumps they were over or right around $100.00 each. I looked them up like a year ago and the price is almost 1/2 now...unless I made a mistake with the part numbers because you can't look them up by application. I just wonder why they are less now than back when I bought them?

:cheers:
Tom

[VetteMed]

I did this "mod" at 17 yrs and about 33k miles. My OE pumps were just a bit tired showing on the low side of the FSM PSI spec spread. I now have 55k miles so figure about 22k miles and 5 yrs worth of use, and the only issue I have had was one of the factory plastic clamps cracked. The holders for the pumps are in great condition as I just looked at them the other day when I pulled it out to check the screw clamps I used to replace the OE plastic clamps.

I know this sounds a bit stupid, but I could actually feel the difference from my original BG pumps and the new ones when I get into the secondaries. My OEM pumps tested right at 46 PSI with the KOEO test, now the Bosch pumps still test at 55 - 54 PSI.

I should mention this as a fwiw. When I bought the Bosch pumps they were over or right around $100.00 each. I looked them up like a year ago and the price is almost 1/2 now...unless I made a mistake with the part numbers because you can't look them up by application. I just wonder why they are less now than back when I bought them?

:cheers:
Tom


Tom, is it possible you looked up the price of a Bosch standard roller-vane type pump rather than the turbine pump? I remember paying around 90-100 each as well, about 3 years ago with my red car, and again 2 years ago with my current Z.

[scottfab]

The modification to the fuel pump holsters was a simple relief cut and will not compromise the ability to hold the pumps. The holsters will outlast the pumps. No problem.

I really hope you're right for all our sake. I mean if it works great but if the only remaining side cracks under the remaining pressure of the oversize pump them ugh. Know what I mean? BTW I would have used a forstner bit to widen the hole rather that put a slit in the holder.

I'm all in favor of improvements toward reliability. I've done it myself on a lot of the systems. As I said in an earlier post, time is the ultimate test as per reliability.

While we're at it though, I think the BS about "pulsing" fuel by the old pumps is an old ploy by sales folks to get you to by something. In this case something that does not fit.

I've taken two failed pumps apart. The failures have to do with "sucking air". The contacts fry very easily if a pump is run in open air at any time. Also there is absolutely no mechanism of "pulsing" the fuel in the our system. The primary pump is on all the time. The fuel system is a closed loop that returns unused fuel back to the tank. Now on my Explorer it's different. The pump is the same type as the vett but the electronics do in fact "pulse" the fuel and there is a device inline that absorbs the pressure pulses. Our ZR-1s have a regulator that drops the pressure to the rail if too high. Whole different concept than the systems (like the explorer) that regulate by turning on and off (pulsing). Even the name of the device is different on the pulsing systems. They're not called "fuel regulators". (can't think of the name right now)

Again the need to use a "turbine" fuel pump aside, I honestly hope your mod holds up. I'd declare it a success if in two years there is no cracking. But then you'd have to take it out and look either by a pump failure or just to "look see".

[VetteMed]

Nobody is holding gun to your head. Those of us who have done this mod are happy with it. If you're uncomfortable with it, it's as easy as just not doing it.


I really hope you're right for all our sake. I mean if it works great but if the only remaining side cracks under the remaining pressure of the oversize pump them ugh. Know what I mean? BTW I would have used a forstner bit to widen the hole rather that put a slit in the holder.

I'm all in favor of improvements toward reliability. I've done it myself on a lot of the systems. As I said in an earlier post, time is the ultimate test as per reliability.

While we're at it though, I think the BS about "pulsing" fuel by the old pumps is an old ploy by sales folks to get you to by something. In this case something that does not fit.

I've taken two failed pumps apart. The failures have to do with "sucking air". The contacts fry very easily if a pump is run in open air at any time. Also there is absolutely no mechanism of "pulsing" the fuel in the our system. The primary pump is on all the time. The fuel system is a closed loop that returns unused fuel back to the tank. Now on my Explorer it's different. The pump is the same type as the vett but the electronics do in fact "pulse" the fuel and there is a device inline that absorbs the pressure pulses. Our ZR-1s have a regulator that drops the pressure to the rail if too high. Whole different concept than the systems (like the explorer) that regulate by turning on and off (pulsing). Even the name of the device is different on the pulsing systems. They're not called "fuel regulators". (can't think of the name right now)

Again the need to use a "turbine" fuel pump aside, I honestly hope your mod holds up. I'd declare it a success if in two years there is no cracking. But then you'd have to take it out and look either by a pump failure or just to "look see".

[scottfab]

[QUOTE=tomtom72;145157]I did this "mod" at 17 yrs and about 33k miles. My OE pumps were just a bit tired showing on the low side of the FSM PSI spec spread. I now have 55k miles so figure about 22k miles and 5 yrs worth of use, and the only issue I have had was one of the factory plastic clamps cracked. The holders for the pumps are in great condition as I just looked at them the other day when I pulled it out to check the screw clamps I used to replace the OE plastic clamps.
/QUOTE]

You cut a slit on the side of each pump holder? And that was at something called "17 yrs" ?
And you are now at year what?
Oh wait I see, 5yrs !!!
Ok maybe this mod has more clock time then I thought. That's different then.
I wish that would have been stated.

[scottfab]

Nobody is holding gun to your head. Those of us who have done this mod are happy with it. If you're uncomfortable with it, it's as easy as just not doing it.

Ah so you've done this mod too? I mean the cutting a slit down the side of the holder? How long ago?
That's an excellent and astute observation though. Why didn't I think of that.
I don't have to do the mod. Gee thanks.

[VetteMed]

Ah so you've done this mod too? I mean the cutting a slit down the side of the holder? How long ago?
That's an excellent and astute observation though. Why didn't I think of that.
I don't have to do the mod. Gee thanks.

My other astute observation is that you seem to argue about stuff just for the sake of arguing. There's no evidence thus far that this modification is in any way compromising the reliability of the fuel delivery system.

I've been driving my ZR-1 daily for ~2 years, 11K miles, with this mod, with no problems. I pulled the assembly out about 3k miles ago and everything looked as it did the day I installed it.

:blahblah:

[scottfab]

My other astute observation is that you seem to argue about stuff just for the sake of arguing. There's no evidence thus far that this modification is in any way compromising the reliability of the fuel delivery system.

I've been driving my ZR-1 daily for ~2 years, 11K miles, with this mod, with no problems. I pulled the assembly out about 3k miles ago and everything looked as it did the day I installed it.

:blahblah:

I take exception to your assertion. Here is my counter to that allegation.
It goes like this. I worry about the other members buying into things hook line and sinker. Look carefully at my other posts. Example, when I read advice that says to bypass safety devices like the clutch switch I remind people about the purpose of the device.Or when it comes to ripping out the secondary actuators I might point out that you can't lower the power to let you son use the car......... Likewise if I see untested and potentially damaging mods I point out the possible down side. I don't see that as argumentative. I see that as being conscientious.
On the mod under discussion, I was obviously wrong and I stated as much. However the data about how long this mod has been tested was not presented until very late.

I will assert that if anyone presented something that was "argumentative" it was you. Your snide remark about "gun to your head...:" was unnecessary. Your second "astute observation" was entirely reasonable to assert. Now if you want to continue this and flame it on be my guest. I'd rather not escalate. My intentions were in the interest of preserving the ZR-1.

[VetteMed]

I've got no desire to escalate anything, I enjoy coming here and exchanging ideas just like I assume you do.

I suppose I can see your point, given the example of the clutch switch.

However, I do object to the idea that this thread was started in order to make anyone fall for something, as if I or anyone else is profiting from this modification. We're all adults, capable of making our own decisions about how to repair and/or modify and/or preserve our cars.

[scottfab]

I've got no desire to escalate anything, I enjoy coming here and exchanging ideas just like I assume you do.

I suppose I can see your point, given the example of the clutch switch.

However, I do object to the idea that this thread was started in order to make anyone fall for something, as if I or anyone else is profiting from this modification. We're all adults, capable of making our own decisions about how to repair and/or modify and/or preserve our cars.

There is absolutely no assertion on my part that this thread was started to make a profit. If it was taken that way it was not my intent. It seems the thread was started to share a fix. Nothing wrong with that. I think it only prudent to point out possible disadvantages to any non cosmetic alteration that could affect reliability. I would expect the same from any member on a post I make if someone feels I've overlooked something. It's a part of exchanging ideas.

I agree totally as you say "We're all adults, capable of making our own decisions about how to repair and/or modify and/or preserve our cars."
I also think we're adult enough to know when a comment is constructive and when one steps over the line.

Now back to the car. I will be practicing what I preach shortly and take in all concerns etc. I may soon be posting on retro fit for the vacuum actuator with an electric solenoid mounted (hopefully) in the same location as the pump is. I designed this in 2002 but at the time had to button up the plenum for a trip. Secondaries have worked fine for these 10 years until this week. If the problem is under the plenum then "game on".

[Paul Workman]

NOTE:

AIRTEX fuel pumps suck. Lasted about a month. Lesson learned......

Well...If they don't suck...they don't work at all, Brett!!:p



p.

[Paul Workman]

The zip ties to put around the slotted cover to hold it tight???

That occured to me as well. However, I'm not a chemist, so I don't know the long term affect gasoline might have on a zip tie. However, a worm-type SS hose clamp might work better and not be suseptible to gas, water, alcohol, etc, yes? Just mulling here...

P.

[VetteMed]

That occured to me as well. However, I'm not a chemist, so I don't know the long term affect gasoline might have on a zip tie. However, a worm-type SS hose clamp might work better and not be suseptible to gas, water, alcohol, etc, yes? Just mulling here...

P.

The factory used zip ties to retain the pumps in the holders, FWIW.

[Paul Workman]

The factory used zip ties to retain the pumps in the holders, FWIW.

Yeah, i 'spoze so. I guess I've seen plenty of brittle plastic on these cars...is what raises the question in my mind. But you're right re the zips.

P.

[tomtom72]

Scott, I apologize. The original pumps were still in the car at 17 yrs old & 33k miles on them. They were down on output. I had a replacement Delphi(?) sender/pump assembly that I bought a long time ago from Partsladie at a good price, but had never installed it.

I saw Andrew's thread about the very premature failure of his Delphi pumps and thought would I do well to consider a swap to the same pumps he used and avoid a possible similar result with the stock replacement pumps that came with the assembly from Delphi. I just figured it would be a crap shoot, but went with the Bosch pumps on a hunch. I have to admit one thing, well two things. I was hesitant to cut up my new assembly, and I maybe off on my time in service...but not the mileage count. I could have sworn I did the pumps about 5 yrs ago, but I maybe wrong. I remember the mileage because I was getting a new set of D3's and the car broke down at the tire store. That's when I pulled the pumps and found the plastic factory clamp had split. I put an ideal clamp in it's place and have looked at the assembly in April of this year and the cut holders seem none the worse for wear. So I would say three years in service, maybe four. It's been awhile and no troubles yet though.

:cheers:
Tom

[scottfab]

...................That's when I pulled the pumps and found the plastic factory clamp had split. I put an ideal clamp in it's place and have looked at the assembly in April of this year and the cut holders seem none the worse for wear. So I would say three years in service, maybe four. It's been awhile and no troubles yet though.


Very good to know. Do you know what the fuel pressure was when installed and what it is now? I replaced mine last year with units from a mfg called "precision". They measured out at 52psi. I am tracking them for how long it takes for them to drop in the years to come.

[tomtom72]

Scott, as I change out my fuel filter every two years and I bleed off the line pressure using my gauge for that. So my gauge is attached so it's easy to test after I change the filter. I know what I'm doing is not by the book to test fuel pump psi. I go to KOEO and look at the gauge, 54 PSI is what I got this past April. I go look under to eye up the filter connections for leaks. Then I start it and she is stone cold at this point so I have time to go look again at cold idle PSI, 54 PSI this year. I go under, again, to make sure I have no leaks and as she is up on stands I don't run at more than idle speed.

I know it's not the correct way to test the pumps, but both should be running if the temp gauge is pined left. I figure if it ever gets to 50 psi then I will do a proper psi test as per the FSM. So far, knocking on wood, the Bosch pumps have done right by me.

:cheers:
Tom

[scottfab]

Scott, as I change out my fuel filter every two years and I bleed off the line pressure using my gauge for that. So my gauge is attached so it's easy to test after I change the filter. I know what I'm doing is not by the book to test fuel pump psi. I go to KOEO and look at the gauge, 54 PSI is what I got this past April.

Excellent. Thank you very much. Longevity is a key issue on these pumps and keeping each other informed on reliability is the key to that. 54psi is a real good number especially after that much time.

[tomtom72]

You're welcome Scott! Oh, just to be accurate about 'time in service' for the Bosch pumps on my car, it is since this thread was started in 09. I saw what Andrew wrote concerning the pumps that came with the replacement pump/sender assembly and just ordered up the Bosch pumps before I did the transplant. So I have 4 yrs and about 23k miles of usage on the Bosch pumps.

:cheers:
Tom

[Paul Workman]

Pardon me for "axing" a dumb question, but is that 54# reading with or without the engine running??? If you jump the pumps with the engine not running, that would be one thing. But, with the engine running, the fuel pressure regulator should be clamping it at around 50-52, no? 54 seems on the high side, to me.

P.

[tomtom72]

:o Sorry, that 54 psi is a KOEO reading.:o

Yes, with the motor running the psi goes down to a reading of 50 psi at idle speed. I just figured that if I see 54 psi doing the KOEO test & a 50 psi at idle speed that she's good to go?

:cheers:
Tom

[Paul Workman]

:o Sorry, that 54 psi is a KOEO reading.:o

Yes, with the motor running the psi goes down to a reading of 50 psi at idle speed. I just figured that if I see 54 psi doing the KOEO test & a 50 psi at idle speed that she's good to go?

:cheers:
Tom

Ah! That makes sense now.

P.

[pantera1683]

Make sure you replace the plastic hose connectors. I replaced my pumps five years ago and was at a car show yesterday. When I attempted to leave she wouldn't start, she had been a little down on power earlier in the day but I thought it just needed to be ran harder since I hadn't driven her in awhile. I pulled the pumps today and found that the hose from one of the hoses was off the pump and the plastic connector had failed. Lesson learned!

[Livin' in the 80's]

http://www.ebay.com/itm/Electric-Fuel-Pump-BOSCH-69225-/292100204760?hash=item44028768d8:g:qi4AAOSwX61ZA7U Y&vxp=mtr

Is this the Pump and is this a legit place that isn't selling a knock off?
I think that I might just replace the fuel pumps as a preventative deal for only $62 delivered from flebay. I might use this pump on my Mastercraft X2 Indmar Boat if the fuel pump craps out again. Removal of the pumps seem relatively easy and fast.
I don't need to be stranded for a $62. fuel pump.

[PhillipsLT5]

Just went with this set up, all good
ACDELCO TS1
ACDELCO TS3
ACDELCO G1
AIRTEX E3240
AIRTEX E3240

[Livin' in the 80's]

Just went with this set up, all good
ACDELCO TS1
ACDELCO TS3
ACDELCO G1
AIRTEX E3240
AIRTEX E3240

Did you have a pump failure or did you replace as a precaution?

[Livin' in the 80's]

Just went with this set up, all good
ACDELCO TS1
ACDELCO TS3
ACDELCO G1
AIRTEX E3240
AIRTEX E3240

How long have you had it in? I looked at the reviews on google for the Bosch and the Airtex and they were both in question. The Bosch seemed to a good choice because it is designed as a turbine pump.

[mhobtr]

Did you have a pump failure or did you replace as a precaution?

I wouldn't replace a working fuel pump just as a precaution. There is a good chance the new one will not be as reliable as the one it replaced.

If you are worried about being stranded, get one of the primary/secondary reverse harnesses so if your primary pump dies, you can get home on the secondary.

Last year I replaced the entire pump assembly on my 91 with a NIB ACDelco unit. Never was pleased and turned out the check valves in both pumps were bad. Replaced the pumps and everything's great now.

BTW, if you buy new pumps, make sure the check valves are working as soon as you take them out of the box. If not, you can get a replacement or refund and not get stuck like I did.

[PhillipsLT5]

I have them in only a few weeks & a few hundred miles, I went with airtex due to Marc's suggestion & Jerry picked it as his #2 suggestion, these guys KNOW, my pump did die on hiway @ 74 MPH in HOV lane on cruise control, engine shut off, motor would start & die in 1 second, literally rolled off hiway, installed fuel pump limp home jumper that I had in car and made it home fine, car did not sound right or run right with jumper installed but it WORKED, thanks again to all who designed, built & sold these, replaced the other pump just as a I am already in there why not, that pump was working but over 27 yrs old and 83K miles

[Roadster]

Interesting thread, a good read....
After reading some other fuel pump threads back in April, I started doing some research about the pumps. Although I have a back up set from Rock Auto, I wanted to check out more info on different pumps.
The one that caught my interest was the Denso Fuel Pump. I know at least one member has them installed. I think the units installed are:
DENSO #951-5016. So checking them out further my info showed me that this particular # is for the LT1 and not the LT5. And let me say that in no way am I referring that this person installed the wrong part. I am just posting the info from my research. And I am not implying in any way that this part # does not work on the LT5, because this member is using them and to my knowledge is very satisfied.
The number that I found to be for the 90-95 LT5 is: DENSO #951-5006
I don't know or have any knowledge of the specs for the two part numbers listed. Again I am just relaying the info that was relayed to me.
Both part #'s to my knowledge are direct fit units. The Denso units can also be a little more expensive, but not over the top.
The Fuel Pump Filters # DENSO 952-0094 are also listed for the LT5.

As of now the 951-5006 pumps are on National Back Order and should be available sometime in the near future for anyone interested.
Just thought I would pass this along......:)

[Livin' in the 80's]

https://uploads.tapatalk-cdn.com/20170505/cd0a1fb62e7a6c6d1a96d05814b4a0cb.jpg

Someone has been here. Aftermarket clamps? What clamps were original?


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[-=Jeff=-]

So I am probably living on borrowed time.. 70K miles and I never pulled the tank unit to replace the pumps.

But I am curious, why couldn't we runt he L98/LT1 single pump? Is it possible? Granted OEM may not be enough fuel but the 255lph might be?

[Roadster]

FYI, it has been said that keeping your tank full will also keep the pumps cooler and more efficient and last longer, because the pumps are submerged in the fuel. And if you always like to run on a low tank, the pumps are not submerged and therefore build up heat because the fuel is not keeping them cool causing them to wear out faster.

After hearing this info, it makes good sense. Just passing it along!!!

[Roadster]

So I am probably living on borrowed time.. 70K miles and I never pulled the tank unit to replace the pumps.

But I am curious, why couldn't we runt he L98/LT1 single pump? Is it possible? Granted OEM may not be enough fuel but the 255lph might be?

Don't think your on borrowed time, mine is also approaching 70k and to my knowledge has not had a pump change. I don't remember see that in the service records that I have.

I think you answered your own question, yes fuel starvation w/OEM single pump...
Even with a more powerful single pump, I would be concerned...JMO

[XfireZ51]

I think that if GM could have gotten away w a single pump, they would have.

[mhobtr]

One of the more popular replacements is the PERFORMANCE ELECTRIC P240KC sold by Rock Auto. There are numerous posts about them and I don't remember any being negative.

They have been out of stock for a while but are now relisted at $19.22 each which is a great deal.

I just ordered two for spares.

[-=Jeff=-]

I think that if GM could have gotten away w a single pump, they would have.

sure 27 years ago.. I wonder if there is a replacement now that would work..

Besides, doesn't a pump shut off after a certain amount of time?

[BigJohn]

sure 27 years ago.. I wonder if there is a replacement now that would work..

Besides, doesn't a pump shut off after a certain amount of time?

Fuel pumps normally shut off when you turn off car.
Fuel injected cars need steady high pressure, plus there is a return line to the fuel tank.

:cheers:

[-=Jeff=-]

Fuel pumps normally shut off when you turn off car.
Fuel injected cars need steady high pressure, plus there is a return line to the fuel tank.

:cheers:

Yes I know that.

the LT5 has TWO pumps.. most find they have a bad pump because the car dies when pump #2 shuts off, Hence the Fuel Pump Jumper harness GC is selling

so.. When does the 2ndary Pump Operate and when does it NOT operate.

**
and not all Fuel injected cars need a return line, in fact many dead head form the pump..

[BigJohn]

Yes I know that.

the LT5 has TWO pumps.. most find they have a bad pump because the car dies when pump #2 shuts off, Hence the Fuel Pump Jumper harness GC is selling

so.. When does the 2ndary Pump Operate and when does it NOT operate.

**
and not all Fuel injected cars need a return line, in fact many dead head form the pump..

When secondary injectors come on for full power would be my guess.

[XfireZ51]

Well if you've eliminated the secondaries, the pump comes on right off idle aside than at first key ON.

[5ABI VT]

I wouldn't replace a working fuel pump just as a precaution. There is a good chance the new one will not be as reliable as the one it replaced.

If you are worried about being stranded, get one of the primary/secondary reverse harnesses so if your primary pump dies, you can get home on the secondary.

Last year I replaced the entire pump assembly on my 91 with a NIB ACDelco unit. Never was pleased and turned out the check valves in both pumps were bad. Replaced the pumps and everything's great now.

BTW, if you buy new pumps, make sure the check valves are working as soon as you take them out of the box. If not, you can get a replacement or refund and not get stuck like I did.

I did change my pumps that were working fine and I do regret it. I have a slight hesitation that I noticed a few times last summer at wot shifting gears. It has me thinking about the clutch but the truth is if the clutch slips Rpms will rise and this is more of a hesitation or a ever so slight pause in acceleration after a hard fast shift. So.. one thing had bugged me from the beggining is one of the pumps I used had a completely different rattle to it and it's been in the back of my mind. I also did use the plastic clips and I'm wondering if they may have come off as well so I've been wanting to tear in there again and replace them while I'm in there with a high performance pump and use better steel clamps.

Interesting thread, a good read....
After reading some other fuel pump threads back in April, I started doing some research about the pumps. Although I have a back up set from Rock Auto, I wanted to check out more info on different pumps.
The one that caught my interest was the Denso Fuel Pump. I know at least one member has them installed. I think the units installed are:
DENSO #951-5016. So checking them out further my info showed me that this particular # is for the LT1 and not the LT5. And let me say that in no way am I referring that this person installed the wrong part. I am just posting the info from my research. And I am not implying in any way that this part # does not work on the LT5, because this member is using them and to my knowledge is very satisfied.
The number that I found to be for the 90-95 LT5 is: DENSO #951-5006
I don't know or have any knowledge of the specs for the two part numbers listed. Again I am just relaying the info that was relayed to me.
Both part #'s to my knowledge are direct fit units. The Denso units can also be a little more expensive, but not over the top.
The Fuel Pump Filters # DENSO 952-0094 are also listed for the LT5.

As of now the 951-5006 pumps are on National Back Order and should be available sometime in the near future for anyone interested.
Just thought I would pass this along......:)

This is interesting because I'm not sure but this may be me you are talking about ! I appreciate you posting the research. I had no idea and never cared to really look into the fuel pump part numbers. I had been planning to change my pumps because on install one pump had a distinct rattle that bothered me (think I posted a video of the rattle -if not will do it today) and I also didn't use the screw steel clamps. For some reason when I think about the plastic becoming brittle and being under stress if overtightened it only makes sense they can split and break easily leaving the hose free to shoot off (pretty sure that's what others have mentioned) . SO... I ordered the twin walbro pumps from Lingenfelter. Not cheap but I feel much more comfortable with Walbro pumps from them. Will post again when they come and I tackle it. Will also change my fuel filter again too.

[mhobtr]

I started suspecting my fuel pumps as a source of sluggish acceleration.

I pulled the pump assembly and was not pleased with the hack job someone had done on replacing the two pumps so I ordered a complete new ACDelco assembly thinking that would solve everything.

I didn't do my homework as I should so I didn't replace the plastic hose clamps and, not knowing any better, I didn't check the backflow check valves in the pumps.

Pressure checked good at idle but performance was not what I expected. I ruled out the pumps because they were new and looked elsewhere but eventually came back to suspecting the pumps. By then I was kicking myself for not replacing the plastic hose clamps so I pulled the assembly and found that the check valves on both pumps were bad.

I bought two new Delphi pumps from Rock Auto, with good check valves, installed them along with new stainless steel hose camps and I am very pleased with the results.

[5ABI VT]

I started suspecting my fuel pumps as a source of sluggish acceleration.

I pulled the pump assembly and was not pleased with the hack job someone had done on replacing the two pumps so I ordered a complete new ACDelco assembly thinking that would solve everything.

I didn't do my homework as I should so I didn't replace the plastic hose clamps and, not knowing any better, I didn't check the backflow check valves in the pumps.

Pressure checked good at idle but performance was not what I expected. I ruled out the pumps because they were new and looked elsewhere but eventually came back to suspecting the pumps. By then I was kicking myself for not replacing the plastic hose clamps so I pulled the assembly and found that the check valves on both pumps were bad.

I bought two new Delphi pumps from Rock Auto, with good check valves, installed them along with new stainless steel hose camps and I am very pleased with the results.

Glad to hear you figured it out was it a hesitation like mine ?

I'm also going to take everyone's advice on the stainless clamps and do that for sure . I will feel happy to find a broken plastic clip but not expecting it!!
Here's a clip I made last year and while I have had other symptoms of my clutch being worn in this case it can be felt and my rpms aren't slipping and rising which is a common clutch -slip symptom but I can feel and hear the delay in acceleration when hitting the next gear and it has made me suspect the pumps. I have changed plugs, wires, coils, injectors, o2 sensors and the map sensor. This video was taken after it all. Leads me back to the beggining .. :neutral:

Around 14-15 second mark in the video.

https://youtu.be/bH7F59FKPEU

[Roadster]

I did change my pumps that were working fine and I do regret it. I have a slight hesitation that I noticed a few times last summer at wot shifting gears. It has me thinking about the clutch but the truth is if the clutch slips Rpms will rise and this is more of a hesitation or a ever so slight pause in acceleration after a hard fast shift. So.. one thing had bugged me from the beggining is one of the pumps I used had a completely different rattle to it and it's been in the back of my mind. I also did use the plastic clips and I'm wondering if they may have come off as well so I've been wanting to tear in there again and replace them while I'm in there with a high performance pump and use better steel clamps.



This is interesting because I'm not sure but this may be me you are talking about ! I appreciate you posting the research. I had no idea and never cared to really look into the fuel pump part numbers. I had been planning to change my pumps because on install one pump had a distinct rattle that bothered me (think I posted a video of the rattle -if not will do it today) and I also didn't use the screw steel clamps. For some reason when I think about the plastic becoming brittle and being under stress if overtightened it only makes sense they can split and break easily leaving the hose free to shoot off (pretty sure that's what others have mentioned) . SO... I ordered the twin walbro pumps from Lingenfelter. Not cheap but I feel much more comfortable with Walbro pumps from them. Will post again when they come and I tackle it. Will also change my fuel filter again too.
Yes Mike, it was you that I was referring too. Just didn't mentioned your name because I didnt want to imply that "I think you ordered the wrong part"
I have a habit of researching and double checking parts #'s and applications. Although I might not need fuel pump replacements in the near future, I did order the LT5 Denso pumps back in April. As mentioned they are on Natioal BO, but as of late last week, my order finally got submitted. So it seems like they are in production.
Will be anxious to hear your report on the pumps you just ordered.
Glad my earler post helped.....


Sent from my SM-G935P using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[5ABI VT]

Yes Mike, it was you that I was referring too. Just didn't mentioned your name because I didnt want to imply that "I think you ordered the wrong part"
I have a habit of researching and double checking parts #'s and applications. Although I might not need fuel pump replacements in the near future, I did order the LT5 Denso pumps back in April. As mentioned they are on Natioal BO, but as of late last week, my order finally got submitted. So it seems like they are in production.
Will be anxious to hear your report on the pumps you just ordered.
Glad my earler post helped.....


Sent from my SM-G935P using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

Definitely helped thank you ! Just knowing that would have made me change them out regardless :) I definitely will post up! I checked after reading your post that they did show available on amazon.ca for the correct part number. But with the strainers (likely wouldn't need another pair) it would have been close to the cost of the lpe pumps which on their website shows are included for the cost so I went with that. I spoke with Ken at lpe briefly and I was convinced (lol). I figured no one really talks about walbro or performance brands much so I at the least I could add something to the forums regarding that setup.

[mhobtr]

Glad to hear you figured it out was it a hesitation like mine ?

I'm also going to take everyone's advice on the stainless clamps and do that for sure . I will feel happy to find a broken plastic clip but not expecting it!!
Here's a clip I made last year and while I have had other symptoms of my clutch being worn in this case it can be felt and my rpms aren't slipping and rising which is a common clutch -slip symptom but I can feel and hear the delay in acceleration when hitting the next gear and it has made me suspect the pumps. I have changed plugs, wires, coils, injectors, o2 sensors and the map sensor. This video was taken after it all. Leads me back to the beggining .. :neutral:

Around 14-15 second mark in the video.

https://youtu.be/bH7F59FKPEU

I doubt you will find a broken plastic clamp but they just don't clamp and seal well. The two pumps "Y" into a single outlet pipe so as the pressure builds, the pipe connections leak and, as time goes on, it gets worse. In my case, I believe I was experiencing the inability of the system to deliver adequate pressure during hard acceleration. I did not try taping my fuel gauge to the windshield but I bet it would have proven me right.

As to the check valves, they shouldn't make any difference when both pumps are running but when the secondary pump turns off during normal driving, the primary pump will short cycle back through the "Y" pipe, into and out of the secondary pump, which will hurt system pressure. In my case, I believed this caused my primary pump to begin intermittent failure. I could drive for short time and "run out of gas". I could then turn the ignition off and restart immediately because the secondary pump would kick in and deliver system pressure.

When I installed my primary/secondary reverse harness, the problem didn't go away because both pumps had the same issue with bad check valves.

When I put the new pumps in, with the steel clamps, the intermittent failures stopped and the performance increased dramatically.

[Roadster]

Definitely helped thank you ! Just knowing that would have made me change them out regardless :) I definitely will post up! I checked after reading your post that they did show available on amazon.ca for the correct part number. But with the strainers (likely wouldn't need another pair) it would have been close to the cost of the lpe pumps which on their website shows are included for the cost so I went with that. I spoke with Ken at lpe briefly and I was convinced (lol). I figured no one really talks about walbro or performance brands much so I at the least I could add something to the forums regarding that setup.

Ok, in the process of more research.....really makes your head spin...
What I would suggest is to make sure your getting the product you need and at the best cost possible.
Case in point, Mike checked Amazon and the Denso 951-5006 unit is listed there for under $20, but their site mentions that it doesn't fit the LT5. The same (think they are the same) units I ordered are more than $20, and are a direct fit for the LT5. The one Denso listed on Amazon is made in China, the Denso unit that Mike used is made in Mexico. I am calling tomorrow to check where the units I have on order will be made.
We would all like a quality product regardless where it is made and hopefully that is what we purchase. I would like to see more USA units made, as with some of the China based automotive products have been in question over the years concerning quality and reliability. That being said, ineffective quality control could take place anywhere.

Also take note that there are many sites that do not distinguish the difference between the LT1 and LT5 fuel pumps in their specs. One exception appears to be Rock Auto that does show a difference in part #'s for the two engines. But one thing I found very interesting is that the
PERFORMANCE ELECTRIC P240KC fuel pumps that are popular are listed for both the LT1 and the LT5, while other brands on their site do show different part #'s pertaining to the different engines.

IMO, this is one of many instances where you really need to check everything out before making a purchase.

[Hog]

Glad to hear you figured it out was it a hesitation like mine ?

I'm also going to take everyone's advice on the stainless clamps and do that for sure . I will feel happy to find a broken plastic clip but not expecting it!!
Here's a clip I made last year and while I have had other symptoms of my clutch being worn in this case it can be felt and my rpms aren't slipping and rising which is a common clutch -slip symptom but I can feel and hear the delay in acceleration when hitting the next gear and it has made me suspect the pumps. I have changed plugs, wires, coils, injectors, o2 sensors and the map sensor. This video was taken after it all. Leads me back to the beggining .. :neutral:

Around 14-15 second mark in the video.

https://youtu.be/bH7F59FKPEU

If you were able to view your WOT fuel pressure I'm thinking it would be ramping up during those periods when you are getting back on the throttle after you upshift.
As soon as you go WOT the ECM would be commanding very high pulsewidths, with all 16 injectors firing the fuel system is fighting to supply them with fuel and it takes a moment to get the fuel pressure back up.
Throwing some powershifts would eliminate your issue I'm guessing as the throttles remain open and there is no ramping up to full power. You would be looking for just under 52 psi at all times, IIRC the OEM regulator is set at 51.8psi for LT5.


A fuel pressure gauge taped to the windshield would tell the tale.


Cutting open fuel filters is a good idea as well. It doesn't take much to start to plug these high pressure fuel systems. I had a 66psi OEM GM system that woudnt rev over 4500rpm at WOT, I was surprised what was in the filter.






Mr Haibeck says that you require 51psi plus or minus 1 psi at WOT 3000-7000rpm. If you see less that 47psi of WOT fuel pressure, reduced power and knocking and possible codes can result. He agrees with talking her for a spin with the gauge taped to the windshield, he does make a good point to use a passenger though. The fuel pressure should snap up to 51 +/-psi (from around 43psi during normal driving when engine vacuum is high) when you stand on the throttle, then you know the FPR is working, or if you are at idle and you disconnect the vacuum supply to the FPR, you will see 51psi or so.

[5ABI VT]

If you were able to view your WOT fuel pressure I'm thinking it would be ramping up during those periods when you are getting back on the throttle after you upshift.
As soon as you go WOT the ECM would be commanding very high pulsewidths, with all 16 injectors firing the fuel system is fighting to supply them with fuel and it takes a moment to get the fuel pressure back up.
Throwing some powershifts would eliminate your issue I'm guessing as the throttles remain open and there is no ramping up to full power. You would be looking for just under 52 psi at all times, IIRC the OEM regulator is set at 51.8psi for LT5.


A fuel pressure gauge taped to the windshield would tell the tale.


Cutting open fuel filters is a good idea as well. It doesn't take much to start to plug these high pressure fuel systems. I had a 66psi OEM GM system that woudnt rev over 4500rpm at WOT, I was surprised what was in the filter.






Mr Haibeck says that you require 51psi plus or minus 1 psi at WOT 3000-7000rpm. If you see less that 47psi of WOT fuel pressure, reduced power and knocking and possible codes can result. He agrees with talking her for a spin with the gauge taped to the windshield, he does make a good point to use a passenger though. The fuel pressure should snap up to 51 +/-psi (from around 43psi during normal driving when engine vacuum is high) when you stand on the throttle, then you know the FPR is working, or if you are at idle and you disconnect the vacuum supply to the FPR, you will see 51psi or so.

I looked briefly for a fuel pressure gauge to tape to the windshield but am not sure what the fitting size is etc. is it the same as an LT1 ? The car never hesitated like that before (few runway events on YouTube I have have no lag whatsoever) I have a few videos I won't post because we were being naughty on the highways at night ;) but the hesitation was much more prominent. It still pulls decent with the hesitation but something is going on.

[Hog]

I looked briefly for a fuel pressure gauge to tape to the windshield but am not sure what the fitting size is etc. is it the same as an LT1 ? The car never hesitated like that before (few runway events on YouTube I have have no lag whatsoever) I have a few videos I won't post because we were being naughty on the highways at night ;) but the hesitation was much more prominent. It still pulls decent with the hesitation but something is going on.
I took a quick look and it looks like the LT1 and Lt5 fitting should be the same. I have no idea on what the fitting size is, all GM stuff was the same, my gauge came with the correct size.


Used on everything GM from 1991-2012.
Description
"Fuel Rail Pressure Relief Valve Distributor-Breakerless ignition (http://www.ebay.com/sch/i.html?_nkw=ignition)"

US$18.26
GM (http://www.ebay.com/sch/i.html?_nkw=gm) p/n 12570619


http://www.rockauto.com/info/321/12570619_Primary__ra_t.jpg



This thread throws around some possible sizes.
http://www.zr1.net/forum/showthread.php?t=26891&highlight=fuel+pressure


Whatever your issue is, the engine sure recovers quickly afterwards. I can totally understand thinking it might be a clutch issue.


After much digging, I found a thread that specifies the correct un regulated or WOT fuel pressure of 50.76 psi. So if you find 51 psi plus or minus 1 psi at WOT your golden. It was tpepmeie who reported the actual LT5 fuel pressure of 50.76psi. At 50.76psi of fuel pressure, the stock injectors will flow 22.14 lb/hr and at 43.5psi they would flow 20.5 lb/hr.


This is the thread where I was referencing Mark Haibecks info.
http://www.zr1.net/forum/showthread.php?t=14739


http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/FPtestLarge.jpg