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Fuel pressure won't hold...

Bedwards

Bedwards

New member
Hey guys. I have the ZZP fuel logs with my setup, and if I turn the key to the 'on' position, my fuel pump will prime to about 40 psi, then slowly goes down to 0 (takes about 2 minutes). I'm assuming the fuel pressure regulator is bad? I'm not sure though. I'm not too experienced with troubleshooting fueling issues.
 


Could be the regulator or the pump. Possibly even a leak somewhere... See or smell any fuel in the engine bay or under the car?
 
Might be worth checking out. I've seen leaking fuel filter connections before that go un-noticed because the smell is not present unless you crouch down near the filter area after the car has been run. The o-ring in the receiver part of the fuel line where the quick-connect end of the filter goes in can go bad and leak.
 
DanGTP said:
Might be worth checking out. I've seen leaking fuel filter connections before that go un-noticed because the smell is not present unless you crouch down near the filter area after the car has been run. The o-ring in the receiver part of the fuel line where the quick-connect end of the filter goes in can go bad and leak.
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Got under it. Can't smell any gas or see any leak.
 


I'd lean towards the FPR.

Take the vacuum line and if it smells like gas, FPR.

To be 100% get a vacuum tester and apply 20 in Hg to it and see if gas comes out.
 
There is a check valve built into our pumps. When teh check valve is bad, pressure bleeds down. It's very common for these to be bad and yet the vehicle to be fine this way.

Beyond a pressure test, is the car acting funny? What is pressure at idle and WOT?

FWIW I've seen cars pass the key click pressure test (GM FSM) and yet..have trouble running at WOT. Put the gauge with a long hose on it and as soon as the throttle gets opened, the pump can't keep up. With the windows down I was screaming at my buddy "Scotty... let off the throttle we are going to go flame out!" Pressure was down to 7psi.
 
matt5112 said:
I'd lean towards the FPR.

Take the vacuum line and if it smells like gas, FPR.

To be 100% get a vacuum tester and apply 20 in Hg to it and see if gas comes out.
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I emailed ZZP and asked them about it. Hopefully they help me out.

BillBoost37 said:
There is a check valve built into our pumps. When teh check valve is bad, pressure bleeds down. It's very common for these to be bad and yet the vehicle to be fine this way.

Beyond a pressure test, is the car acting funny? What is pressure at idle and WOT?

FWIW I've seen cars pass the key click pressure test (GM FSM) and yet..have trouble running at WOT. Put the gauge with a long hose on it and as soon as the throttle gets opened, the pump can't keep up. With the windows down I was screaming at my buddy "Scotty... let off the throttle we are going to go flame out!" Pressure was down to 7psi.
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Does this require a new pump?
 


If the car runs normally and you don't loose pressure under load, I'd guess you're okay for now on the pump. If your pressure starts dropping off under boost, it might be time to replace it again (maybe with a Walbro this time).
 
Personally I can't spend the money on a Racetronix or Walbro after pickup up TREPerformance.com's high flow pump for my Bonne, a regular one for my truck and knowing a bunch of other guys running these pumps without any issues (less the one posted this week here. Still not sure if that's the pump or something else).
 
Normal! does it maintain pressure while running? the aftermarket FPR they use bleeds off the pressure this is why ZZP recommends turning the car to the on position and waiting 4 sec before cranking it when you use logs
 
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BillBoost37 said:
Personally I can't spend the money on a Racetronix or Walbro after pickup up TREPerformance.com's high flow pump for my Bonne, a regular one for my truck and knowing a bunch of other guys running these pumps without any issues (less the one posted this week here. Still not sure if that's the pump or something else).
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WOW that's a great price on a 255lph pump! I'm looking for an upgrade, so this may be my next purchase.
 
DanGTP said:
WOW that's a great price on a 255lph pump! I'm looking for an upgrade, so this may be my next purchase.
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Also on the 97-00 gtp pump they come with a new venturi feed line and new heat sink/pump holder cover thing. The prj kit does not come with one and the used pump cover was a ***** to get off and then back on to the new and wider walbro. I ended up using a lot of vaseline and it still split the cover, but it will still hold it in place.
 


DanGTP said:
WOW that's a great price on a 255lph pump! I'm looking for an upgrade, so this may be my next purchase.
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That's what I said when I did it. I originally figured if it was crap then I wouldn't be upset. Meanwhile I've found out there's a bunch of GP/Regal guys using them for pumps with great results also.
 
01gpgt01 said:
Normal! does it maintain pressure while running? the aftermarket FPR they use bleeds off the pressure this is why ZZP recommends turning the car to the on position and waiting 4 sec before cranking it when you use logs
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Really? It maintains pressure around 35-40 psi while idling.
 
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