Not holding pressure/hard to start

JamesVinar

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I know alot of you go between here and LOD but i figured id ask anyway.
My car doesnt seem to hold fuel pressure for more than 2 minutes after shutoff which causes it to have long cranking and a kind of stumbling start, originally i did the fuel pump to do it since my pressure was 28psi running. Worked for maybe a day then i was back to this, sometimes it will hold pressure longer than others.

I have no codes for fuel injectors or misfires and when i pulled the vac line off the FPR no gas came out. There was a faint smell of gas under the hood. Another thing is i cant always hear my pump when i put the car in ON might just be my hearing though.
 

soduka

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Have you checked the dedicated part whose mission is to do exactly this, the Fuel Pressure Regulator on the Fuel Rail?
 

chris2523

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check pressure car off. (i believe you said this drops quickly zero.)
check pressure at idle, regulator vacuum hooked up and unhooked.
check pressure under load.
 

JamesVinar

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Turns out My brother had a new regulator so I'll throw that one in later. There's 2 on the car right?
 

JamesVinar

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Whats the thing on the passenger side rail then? looks like a FPR but held in with a snap ring instead
 

Rockbottom

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How all do i test this? People normally just tell me to see if gas is coming out
How all do i test this? People normally just tell me to see if gas is coming out
Go rent a free fuel pump tester at auto zone. Hook it up and measure the psi. You need a credit card and they refund it back to the card upon returning the tester
 

chris2523

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Whats the thing on the passenger side rail then? looks like a FPR but held in with a snap ring instead

its a pulse dampener.
for this exercise, its not relevant as long as it is not leaking.

35psi at reg and holds. With it off 45. Dead 0 otherwise

good pressures.

the lack of pressure after the pump shuts down most likely means the check valve in the pump isn't holding.
annoying, but a non issue as long as the pressure builds quickly when the pump is running.

should not take more than a second or two.
 

JamesVinar

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Brand new pump so that shouldnt be bad, maybe its like walbro and just doesnt have one.
This is the odd part, i can prime it but it will only run maybe a second or two and not build pressure. I wouldnt say its the relay since well the pump works when the cars on.
 

JamesVinar

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Does anyone know if the check valve is part of the pump or pump assembly?
Also would it be possible to put the top on wrong? Like theres 2 wholes im the pump assembly cap, one sits on the pump and the other sits over something else, would it be possible to put that on backwards? It looked like it only went on one way
 

93mark8rules

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I forgot but isnt there a check valve or something on the sending unit in the tank that the pump would attach to? I have a brand new pump also and the same problem but mine takes a a couple hours to bleed down to about 28psi and I end up with a long crank before starting. But if I cycle the key once before starting it the pump is primed and fires right up.

If you cycle the key once before starting does yours start right up? Dumb question but how old is your fuel filter?
 

driller

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This is the odd part, i can prime it but it will only run maybe a second or two and not build pressure.

The fuel pump only runs a second or two when the key is turned to ON. This is normal. But it should build pressure when it does.
 

chris2523

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Does anyone know if the check valve is part of the pump or pump assembly?
Also would it be possible to put the top on wrong? Like theres 2 wholes im the pump assembly cap, one sits on the pump and the other sits over something else, would it be possible to put that on backwards? It looked like it only went on one way

i have never had a gen2 pump in my hands but the gen 1 check valve is in the pump.
google pics seems to confirm this.
bad check valves in walbros is actually quite common.
 

JamesVinar

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I see that 93-98 is the same part numbers so this should be good, what are the chances that the new pumps bad since it takes 10 primes to start with pressure
 

soduka

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Gen 1 and Gen 2 pumps are not at all interchangeable so whatever source you're reading, if you are referring to the pump itself, is mistaken and I would discount it from further reference if it can't get that right. Gen 2 uses an entirely different fuel delivery system compared to Gen 1 and its pumps are unique.
 

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