LT5 fuel pump?

[Schrade]

Welcome onto the boards there limo...

I put an Airtex in my '98 GMC [$323 from Advance], against recommendations of others w/A-Tex experience. The rap was that they fail often, and pumps can fail from getting hot. Gasoline keeps them cooled.

I keep my tanks full, so mine never got hot. None-the-less, it went belly up after 2 years. I had a ton of crud when I did it last month. The in-line filter was pretty plugged too.

I replaced it with something besides AirTex ($40 on eBay). I might get what I paid for, and maybe not.

I emptied the tank, filled it with aquarium gravel + some soapy water, and shook it for about :20. Then rinsed til it drained clear, dumped in some motor oil + WD from a gallon can to coat the tank interior and stop flash rust, the installed, and fired it.

Did you get fuel pressure tests done?

[limo1988]

Yes, I did buy a fuel pressure gauge, hooked it up, and at idle have 10 PSI! If I try pushing the pedal down very far, it stumbles. From idle I can ease it up a little bit and that is all. So looks like I need a fuel filter, fuel pump, or both..... Thanks to everybody for all of the good advice. And there sure are a lot of opinions on which of the many fuel pumps to install. Looks like the AC/DELCO complete unit from ROCK Auto for $299 is the best buy. And I watched a Youtube video on replacing the fuel filter. Looks like a bear to do, but much cheaper than going straight to the pump.
Dare I ask which is the correct fuel filter to install on a ZR1???

Thanks again, Limo1988(Steve)

[cvette98pacecar]

Originally Posted by limo1988

Yes, I did buy a fuel pressure gauge, hooked it up, and at idle have 10 PSI! If I try pushing the pedal down very far, it stumbles. From idle I can ease it up a little bit and that is all. So looks like I need a fuel filter, fuel pump, or both..... Thanks to everybody for all of the good advice. And there sure are a lot of opinions on which of the many fuel pumps to install. Looks like the AC/DELCO complete unit from ROCK Auto for $299 is the best buy. And I watched a Youtube video on replacing the fuel filter. Looks like a bear to do, but much cheaper than going straight to the pump.
Dare I ask which is the correct fuel filter to install on a ZR1???

Thanks again, Limo1988(Steve)

Stock filter. Nothing special there. Get one from Rock Auto when you buy the pump assembly. There are two pumps.

[Schrade]

WHOA!!!

Good job on DYNAMIC fuel pressure. Now do STATIC fuel pressure.

Don't buy a filter or a pump yet.

Check pressure leakdown time first.

If you have a leak in the line, your filter and your pump might be fine.

If you have leaking injectors, your filter and your pump might be fine.

If your FP regulator bladder is ruptured, your filter and your pump might be fine.

If you have a bad in-line check valve, your filter and your pump might be fine.

Probably a few more things can be wrong, and your filter and your pump might be fine.

Not much sense in replacing fine parts (although that IS the American way).

Originally Posted by limo1988

Yes, I did buy a fuel pressure gauge, hooked it up, and at idle have 10 PSI! If I try pushing the pedal down very far, it stumbles. From idle I can ease it up a little bit and that is all. So looks like I need a fuel filter, fuel pump, or both..... Thanks to everybody for all of the good advice. And there sure are a lot of opinions on which of the many fuel pumps to install. Looks like the AC/DELCO complete unit from ROCK Auto for $299 is the best buy. And I watched a Youtube video on replacing the fuel filter. Looks like a bear to do, but much cheaper than going straight to the pump.
Dare I ask which is the correct fuel filter to install on a ZR1???

Thanks again, Limo1988(Steve)

[limo1988]

Hey, Schrade,

When I hooked up my fuel pressure gauge, the first thing that I did was turn the key to the ON position. I looked at the gauge, and it stayed at 0 pressure. Then I turned the key to Start position and the engine started and idled. That is when I registered 10 PSI. What does it mean if when Key ON and Engine OFF gives you 0 pressure? My pump must be working somewhat since the engine will start and idle at 10 PSI. Is one pump suppose to be working with the Key On Engine Off and the other pump (or both) working with Key On Engine On?

Thanks for the help... Limo1988(Steve)

[Schrade]

Not sure Steve...

On L98 (just a different TPI), pump would prime rails to pressure for 2 seconds, and pump would NOT re-start until a tach signal reached a certain RPM level.

Since yours DOES start, you have a drastic leakdown somewhere, and your diags won't depend on running engine.

It doesn't make sense that you have 0 PSI primed pressure. Maybe you DO have 10 primed, and it bleeds off before you can see the gauge???

Put the gauge where you can see it THE MOMENT that you turn the key to Start.

Note pressure.

Pull the vacuum hose to FPR, and see if there's gas in it. If so, the bladder is ruptured.

Next thing, if no fuel in FPR Vac supply hose, is to GENTLY pinch RETURN fuel line (use Vise-Grips, WITH SHOP RAG), and repeat test. That will rule out weak FPR bladder spring...

Post results...

[Hog]

Originally Posted by Schrade

Not sure Steve...

On L98 (just a different TPI), pump would prime rails to pressure for 2 seconds, and pump would NOT re-start until a tach signal reached a certain RPM level.

Since yours DOES start, you have a drastic leakdown somewhere, and your diags won't depend on running engine.

It doesn't make sense that you have 0 PSI primed pressure. Maybe you DO have 10 primed, and it bleeds off before you can see the gauge???

Put the gauge where you can see it THE MOMENT that you turn the key to Start.

Note pressure.

Pull the vacuum hose to FPR, and see if there's gas in it. If so, the bladder is ruptured.

Next thing, if no fuel in FPR Vac supply hose, is to GENTLY pinch RETURN fuel line (use Vise-Grips, WITH SHOP RAG), and repeat test. That will rule out weak FPR bladder spring...

Post results...

He is stating that he has 10 psi AS THE CAR IS IDLING.


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What does it mean if when Key ON and Engine OFF gives you 0 pressure? My pump must be working somewhat since the engine will start and idle at 10 PSI. Is one pump suppose to be working with the Key On Engine Off and the other pump (or both) working with Key On Engine On?
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10 psi sure is a low spec. The injector spray pattern must be horrible. I'm surprised it fires.

Pressure gauge good?

There are these cool little clamps you can buy for compressing fuel lines. Perfect for the excellent diagnostics procedures Schrade gave above.

example

[limo1988]

When I turned the key to the ON position without starting the engine, I stood up and looked at the gauge sitting on top of the engine and NO reading visible. I stared at it for a moment and then squatted down into the car to push in the clutch pedal to start the engine. Only when running did I get a fuel pressure reading.

Sorry but I will be away from home for the next 3 weeks(out of the Arizona heat) and my ZR1 is all settled in with its cover on it. So I will pick up the diagnosing at the end of August. and thanks again for all the help.
Limo1988(Steve)

[Schrade]

Originally Posted by limo1988

When I turned the key to the ON position without starting the engine, I stood up and looked at the gauge sitting on top of the engine and NO reading visible. I stared at it for a moment and then squatted down into the car to push in the clutch pedal to start the engine. Only when running did I get a fuel pressure reading.

Sorry but I will be away from home for the next 3 weeks(out of the Arizona heat) and my ZR1 is all settled in with its cover on it. So I will pick up the diagnosing at the end of August. and thanks again for all the help.
Limo1988(Steve)

It's beyond me how it's starting with no fuel pressure.

Never mind nominal dynamic FP......................................

[5ABI VT]

Originally Posted by cvette98pacecar

Here is a link for the Bosch pump and gasket.

Part Number Description Comments
68238 Fuel Pump Tank Seal
68001 Fuel Pump Strainer
69223 Electric Fuel Pump In-Tank

http://www.boschautoparts.com/Vehicl...artFinder.aspx

I ordered the 69223. Then I read later 69225... Just a bit confused here but did the 69223 work for factory replacement ??