Walbro 255 fuel pump?

[Tony Davila]

Okay I have given up searching this forum to see if anyone has tried using the 96 7.4 Suburban Walbro fuel pump in their Z. I have to now replace my secondary and was curious if anyone has tried that pump.

Lingenfelter has a Walbro twin replacement fuel pump assembly for our cars on his website. I was contemplating using a Walbro pump on my secondaries only because I didn't want to use another Airtec if possible.

Walbro F20000169 255LPH Fuel Pump Chevrolet Suburban 1996 - 1997

[DaveK]

No knowledge of them myself but there was a previous post about them:

http://www.zr1.net/forum/showthread.php?t=3984&highlight=walbro

Maybe the posters can provide more information.

Dave

[Tony Davila]

No knowledge of them myself but there was a previous post about them:

http://www.zr1.net/forum/showthread.php?t=3984&highlight=walbro

Maybe the posters can provide more information.

Dave

Thanks..... that is what I needed to know. I did Head and Cam work on engine and now every so often it falls flat after 7k. Pump pressure was 48psi on secondary. I might just do that swap.

Tony

[Pete]

Thanks..... that is what I needed to know. I did Head and Cam work on engine and now every so often it falls flat after 7k. Pump pressure was 48psi on secondary. I might just do that swap.

Tony


Let me take a wild guess,you installed Stage I cams?:)

Pete

[Tony Davila]

Let me take a wild guess,you installed Stage I cams?:)

Pete

You have my curiosity..... Yes I do, okay.... what is up?:neutral:
I forgot to mention my wideband A/F indicates lean during that time, like it is starving for fuel.

Tony

[Pete]

Been saying it, i've been SCREAMING it, nobody is listening.
You can lead a horse to water you can't make him drink.

EXHAUST CAMS ARE TOO BIG

We have 3 FBI 10 second Z's big motors, they all have smaller exhaust cams then your Stage I's.

This is about as far as i will go on this matter on here as much as i wanna say more,but i will get the boot.:)

After you add the fuel you will be told to do a ???????? i know what it is. Can anyone else guess.
I'm here for you to guess what's coming next for your Z.

Pete

PS
Tony,i don't mean to come off strong/harsh.
I know you spend some money.
Anybody that knows me knows if you ask me a question i will give you a straight answer,as a good friend of mine (wazoo guy) told me once i'm no salesman,i love him for being straight with me and i can not argue with the truth,he's right i'm no saleman.

I don't mean to come off harsh/strong if you say the word i will delete my post just say the word.

[DaveK]

This is about as far as i will go on this matter on here as much as i wanna say more,but i will get the boot.:)

Where did this "freedom of speech but only if you agree with me or say nothing controversial" thing come from? I seem to see it far too often these days. Isn't the essence of democracy that we all have a right to state and debate our opinions?

Speak up Pete, if they ban you or something I'll put up the bail money! That said I don't believe anyone running the registry would have a problem with open and honest debate or discussion.

"I disapprove of what you say, but I will defend to the death your right to say it" - E.B. Hall, The Friends of Voltaire.

[XfireZ51]

You have my curiosity..... Yes I do, okay.... what is up?:neutral:
I forgot to mention my wideband A/F indicates lean during that time, like it is starving for fuel.

Tony

Tony,

Does that mean your VE table is maxxed out at the top!!? Who did the tune?
Pete and I were just talking about Stage 1 cams and how really the LT-5 doesn't need more exhaust. Already pretty efficient and better breathing exhaust system makes it better. Bigger exhaust cam has too much overlap with valve closing late and taking some of the air/fuel charge out the exhaust port. FU told me once he believed the motor came "overcammed" from the factory and given the improvement we get with just porting, I agree with him. This is why I decided to onstall only a larger intake cam with my ported heads.

[RHanselman]

We put two Walbro's in the turbo car but I'll have to look back at the receipt to see which ones...

[Tony Davila]

Been saying it, i've been SCREAMING it, nobody is listening.
You can lead a horse to water you can't make him drink.

EXHAUST CAMS ARE TOO BIG

We have 3 FBI 10 second Z's big motors, they all have smaller exhaust cams then your Stage I's.

This is about as far as i will go on this matter on here as much as i wanna say more,but i will get the boot.:)

After you add the fuel you will be told to do a ???????? i know what it is. Can anyone else guess.
I'm here for you to guess what's coming next for your Z.

Pete

PS
Tony,i don't mean to come off strong/harsh.
I know you spend some money.
Anybody that knows me knows if you ask me a question i will give you a straight answer,as a good friend of mine (wazoo guy) told me once i'm no salesman,i love him for being straight with me and i can not argue with the truth,he's right i'm no saleman.

I don't mean to come off harsh/strong if you say the word i will delete my post just say the word.

Pete I like your honesty. If there is something to be learned I am all ears.:handshak:
I have Stage 1 cams installed that are my reground stock ones. Aaron Scott did mine for me back last April. I ported my own heads (saved in cost but almost had a heart attack), Aaron's machine shop put my tapperd valve guides in and did the standard 3 angle valve job. Aaron also timed my cams for me and I did the rest of the reassembly to get it running.

I am running 1 .75 Watson headers not the 2" from SW. I didn't think my 350 needed 2" headers and I was trying to keep my bottom end torque; I think it worked, I noticed no loss in bottom end but a re-dyno run will confirm. I am not smart enough to know if my exhaust cams are too big but I believe you, I just can't do anything about it now or would know the difference. Now you just made me feel better about having smaller headers then the norm.

My tune is from Aaron with secondaries removed....just to get it running until I can re-dyno it for proper tune. It is very close (A/F) though and it runs awesome.

Back to my original post about the Walbro FP, it was just a question to see if somebody has done it already. I based my FP issues off of my assessment and diagnosis of my FP pressure being 48psi on my secondary fuel pump and that it is over 20yrs........ I haven't had any issues with it until just recently. Thanks

The finished product......
Tony D.
http://i69.photobucket.com/albums/i66/Zrace1/IMAG0084.jpg

[HAWAIIZR-1]

Pete,

I'm all ears and have SGC Stage I cams too, but I don't know about any issues yet and very pleased with the way it runs. I have not flattened out at 7,200 rpms but only took it up that high once since I just broke it in and working to get pass emissions with different tune. Having said that, I'll know when I give up (fail) or pass emissions and put the headers back on with X pipe and some dynomax etc. and get it dyno tuned. I'll post the results and what issues I ran into.

I believe you if you said it about the exhaust cams as evidence by everything you have done so far and proven. Not all the tuners for the LT5 agree with each other, in fact they all seem to believe differently about certain things so understood. We all take the risks with who we believe or trusted at one time. Get me once, but you won't get me twice. Thanks for your honesty and sharing the truth.

Craig

[HAWAIIZR-1]

Pete I like your honesty. If there is something to be learned I am all ears.:handshak:
I have Stage 1 cams installed that are my reground stock ones. Aaron Scott did mine for me back last April. I ported my own heads (saved in cost but almost had a heart attack), Aaron's machine shop put my tapperd valve guides in and did the standard 3 angle valve job. Aaron also timed my cams for me and I did the rest of the reassembly to get it running.

I am running 1 .75 Watson headers not the 2" from SW. I didn't think my 350 needed 2" headers and I was trying to keep my bottom end torque; I think it worked, I noticed no loss in bottom end but a re-dyno run will confirm. I am not smart enough to know if my exhaust cams are too big but I believe you, I just can't do anything about it now or would know the difference. Now you just made me feel better about having smaller headers then the norm.

My tune is from Aaron with secondaries removed....just to get it running until I can re-dyno it for proper tune. It is very close (A/F) though and it runs awesome.

Back to my original post about the Walbro FP, it was just a question to see if somebody has done it already. I based my FP issues off of my assessment and diagnosis of my FP pressure being 48psi on my secondary fuel pump and that it is over 20yrs........ I haven't had any issues with it until just recently. Thanks

The finished product......
Tony D.
http://i69.photobucket.com/albums/i66/Zrace1/IMAG0084.jpg

Glad to hear you have been having good luck with Aaron Scott. I'm still waiting for my receipts for over 2 years now and my car barely ran with his tuned chip; but I did not even bother to go back to resolve and gave up.

[XfireZ51]

Tony,

BTW, I have 1.75" Watsons on my car. Frankly, I don't think the extra .25" makes any difference. Marc H. Has agreed whenever we have discussed it. Certainly not on a 5.7L motor. My opinion is that if you suspect a fuel pump,
then replace w the stock Suburban pumps. That's what I use. Replace the pump filter socks as well. However, I wouldn't conclude that the stock pumps don't flow enough unless there's a problem w them. Any chance you have a copy of the calibration currently being used? PM me if you 'd like.

[Demps]

I also have an SGC stg I cam'd 350. Runs like a scalded dog below ~6,800rpms. Pete and I have talked extensively about over-cam'd exhaust. I'm going to leave mine alone, mechanically at least. The car has an open loop chip--runs rich and gets poor gas mileage but has instantaneous throttle response. The FBI prom lessons learned don't/haven't translated to my '95.

When Aaron was interested in LT5s, there was none better. This was supposedly his first 4-bolt cam'd 350. Jim Smith went open loop as the cam tuning proved troublesome.

Ted

[Paul Workman]

Just following along here...

After scratching my head after all static indicators didn't turn up anything, taping the pressure gauge to the windshield and making a few WOT pulls reveiled issues with one of my pumps.

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

Adding insult to injury, the replacement pump (an Airtec, BTW) had a bad check valve, as it turned out, which introduced another round robin troubleshooting stint.:mad: However, in both cases, the fault was detected by this gauge taped to the windshield - dynamic - test.

Hope this helps someone.;)

P.

[Pete]

Pete,

I'm all ears and have SGC Stage I cams too, but I don't know about any issues yet and very pleased with the way it runs. I have not flattened out at 7,200 rpms but only took it up that high once since I just broke it in and working to get pass emissions with different tune. Having said that, I'll know when I give up (fail) or pass emissions and put the headers back on with X pipe and some dynomax etc. and get it dyno tuned. I'll post the results and what issues I ran into.

I believe you if you said it about the exhaust cams as evidence by everything you have done so far and proven. Not all the tuners for the LT5 agree with each other, in fact they all seem to believe differently about certain things so understood. We all take the risks with who we believe or trusted at one time. Get me once, but you won't get me twice. Thanks for your honesty and sharing the truth.

Craig

Ok,you guys asked for it LOL
I will get flack for this,oh well no guts no glory.
Let me say that any cams passed thru my hands have been checked/spec'd.

If a good tuner done some,not a whole lot just some and knows anything about performance 101 they would know that 75-80% Intake/Exhaust ratio is very good to perfect.
If they took the time and flowed LT5 heads either stock or ported they would find out I/E ratio is way above and beyond 80%.
LPE has done research on this and it shows on his LT5 cam specs he was selling.
So question is if I/E ratio is 90% do we need more exhaust especially on small cube motors.

If you guys went with Stage III intakes & Stage I exhausts with some extensive porting,i would say ok.
The issue i see with Stage I intake cams they are not much bigger if any over stock intake cams so it's like putting in big exhaust cams with stock intake cams.

The other issue is tuning it could be made to run ok but no matter what you do you'll get fumes at idle,overlap.

At this time i'm testing Stage III intake with .224 exhaust,i don't know if i went overboard with the cams for 350ci,we'll find out or will i have to go back to the smaller .236in .220ex

Need more proof i had Stage II .237 .440 cams on a 415 car made good power tuning was a mother, she ran ok but idle fumes were forget bout it.
Anyway we changed to .224 exhaust cams that was the only change we made, picked up 25-30 accross the whole RPM range tunability/driveability was way way better.
Need more proof Ted's 415 peak #'s are as good or better but look below that and forgetboutit.


Pete

[DaveK]

Thanks for explaining, Pete. Much appreciated even I'm not going there anytime soon :)
Always good to be informed though - never know when the lottery win might come!

[Demps]

The other issue is tuning it could be made to run ok but no matter what you do you'll get fumes at idle,overlap.

At this time i'm testing Stage III intake with .224 exhaust,i don't know if i went overboard with the cams for 350ci,we'll find out or will i have to go back to the smaller .236in .220ex

Need more proof i had Stage II .237 .440 cams on a 415 car made good power tuning was a mother, she ran ok but idle fumes were forget bout it.
Anyway we changed to .224 exhaust cams that was the only change we made, picked up 25-30 accross the whole RPM range tunability/driveability was way way better.
Need more proof Ted's 415 peak #'s are as good or better but look below that and forgetboutit.


Pete

My 415 is good. Tune could use a slight tweak down low ~2,000-2,800rpms for drive ability purposes. Running LPE B cams:

The intakes are 239 degrees and .448 lift.
The exhausts are 221 degrees and .399 lift.

Ted

[HAWAIIZR-1]

Ok,you guys asked for it LOL
I will get flack for this,oh well no guts no glory.
Let me say that any cams passed thru my hands have been checked/spec'd.

If a good tuner done some,not a whole lot just some and knows anything about performance 101 they would know that 75-80% Intake/Exhaust ratio is very good to perfect.
If they took the time and flowed LT5 heads either stock or ported they would find out I/E ratio is way above and beyond 80%.
LPE has done research on this and it shows on his LT5 cam specs he was selling.
So question is if I/E ratio is 90% do we need more exhaust especially on small cube motors.

If you guys went with Stage III intakes & Stage I exhausts with some extensive porting,i would say ok.
The issue i see with Stage I intake cams they are not much bigger if any over stock intake cams so it's like putting in big exhaust cams with stock intake cams.

The other issue is tuning it could be made to run ok but no matter what you do you'll get fumes at idle,overlap.

At this time i'm testing Stage III intake with .224 exhaust,i don't know if i went overboard with the cams for 350ci,we'll find out or will i have to go back to the smaller .236in .220ex

Need more proof i had Stage II .237 .440 cams on a 415 car made good power tuning was a mother, she ran ok but idle fumes were forget bout it.
Anyway we changed to .224 exhaust cams that was the only change we made, picked up 25-30 accross the whole RPM range tunability/driveability was way way better.
Need more proof Ted's 415 peak #'s are as good or better but look below that and forgetboutit.


Pete


Pete,

Thanks for sharing all your knowledge and experience with this topic about Stage I cams. Very valuable information and very curious how it runs in the end once dyno'd and fine tuned. Maybe someone like myself won't see or know the difference, but proven by your testing. I am very please with them and could have saved $800 based on your findings to have not replaced the exhaust cams and just the intakes. Now I am even more curious to see what is laid down to the rear wheels when all the tuning is done. I may never be able to drive my car like you do, but I sure do enjoy it none the less. Like many others, I'm not getting into learning how to tune these cars myself as I find mail order tuning only goes so far. Right now my car is running rich in all areas and conditions so it is being addressed too. Thanks again!!

Craig

[Tony Davila]

Glad to hear you have been having good luck with Aaron Scott. I'm still waiting for my receipts for over 2 years now and my car barely ran with his tuned chip; but I did not even bother to go back to resolve and gave up.

I understand you and you are not alone on that issue. I have heard it before.

Pete,

Thanks for sharing all your knowledge and experience with this topic about Stage I cams. Very valuable information and very curious how it runs in the end once dyno'd and fine tuned. Maybe someone like myself won't see or know the difference, but proven by your testing. I am very please with them and could have saved $800 based on your findings to have not replaced the exhaust cams and just the intakes. Now I am even more curious to see what is laid down to the rear wheels when all the tuning is done. I may never be able to drive my car like you do, but I sure do enjoy it none the less. Like many others, I'm not getting into learning how to tune these cars myself as I find mail order tuning only goes so far. Right now my car is running rich in all areas and conditions so it is being addressed too. Thanks again!!

CraigPete I agree with Craig, thanks..;)..I could have saved $800. My tune I got from Aaron is pretty close, not perfect, it has its quirks but Jim Smith might have gotten the tune a lot tighter than before. I might still get a Haibec chip because I hear they are better with their tune.

Tony

If they took the time and flowed LT5 heads either stock or ported they would find out I/E ratio is way above and beyond 80%.
LPE has done research on this and it shows on his LT5 cam specs he was selling.
So question is if I/E ratio is 90% do we need more exhaust especially on small cube motors.
Pete, I see and understand your point on what you said above. I might not have an issue with my exhaust cams being too big or I might have accidentally compensated for them being too big when I ported the exhaust side. I only cleaned up and improved the flow but did not hog then out. The port size is still smaller than the gasket opening. My goal was to port my heads for improved velocity both intake and exhaust hence my smaller header size. She runs awesome, I might have done something right and not know it.:cheers:

Tony

[HAWAIIZR-1]

Thanks Tony and sorry for invading your post orginally for fuel pump question. You car is awesome and great job regardless. I'm not trying to beat Pete's timeslips and never will, but am concerned if long term these cams are no good for the 350. But like you said, it runs like a bat of hell so it is hard for me to fault them at this point and not knowing better would do it again; knowing what I know now I would wholeheartedly take Pete's advice. I personally know what it takes to replace and time camshafts properly so I can appreciate all the testing that Pete has done with all the possible combinations.:cheers:

[Tony Davila]

Thanks Tony and sorry for invading your post orginally for fuel pump question. You car is awesome and great job regardless. I'm not trying to beat Pete's timeslips and never will, but am concerned if long term these cams are no good for the 350. But like you said, it runs like a bat of hell so it is hard for me to fault them at this point and not knowing better would do it again; knowing what I know now I would wholeheartedly take Pete's advice. I personally know what it takes to replace and time camshafts properly so I can appreciate all the testing that Pete has done with all the possible combinations.:cheers:

Craig no issue on the post, if we were standing in the parking lot with beer in hand by our cars BS-ing we would have covered this anyways.

I ordered my Walbro 255lph pump for a 96 Suburb 7.4, and will put it in when I get home. I am at Fort Drum, NY doing ARMY stuff and don't know what this white stuff is floating in the air around here. ")

Tony:saluting:

[HAWAIIZR-1]

Craig no issue on the post, if we were standing in the parking lot with beer in hand by our cars BS-ing we would have covered this anyways.

I ordered my Walbro 255lph pump for a 96 Suburb 7.4, and will put it in when I get home. I am at Fort Drum, NY doing ARMY stuff and don't know what this white stuff is floating in the air around here. ")

Tony:saluting:

Thanks for your thoughts Tony and understand. Best wishes on the fuel pump and I hope that solves it for you.

Fort Drum, NY..........yeah, been there and remember the huge ice storm they had years ago or is that a regular occurence? All those powerlines had issues.

We had our white stuff yesterday, but beautiful spring weather now. Heading to work to the smallest Army post in the world. Just my Army unit and a few others here on the dock in Yokohama....nice and quiet the way I like it now that I am retired. Take care and Aloha!! Craig

[Tony Davila]

Okay just for general info, I installed the WALBRO 255lph fuel pump in my car (Secondary Pump) which was designed for the 96 suburban 7.4lt truck.
My Z is not starving for fuel past 7k anymore, problem solved.

Special note:


You will have to modify the bottom of the fuel pump plastic container, the WALBRO fuel pump is not tapered at the bottom like the factory unit.
The WALBRO pump is 1/16" larger at the bottom. I had to remove about 1/2" off the bottom of the plastic container in order to get it to fit all the way down, other than that no issue.:cheers:

[DaveK]

Great news. Thanks for the follow up :cheers: