Fuel pump ???

[tony42]

Hey gn fam need help. With key turn on fuel pressure goes to 45 psi then instantly drop to 0. i dont hear pump prime check fuses n relays all good i have hot wire disconnect return original some results will not hold pessure

 

[mikestertwo]

If you have pressure the pump is priming. You have a leak somewhere. Could be fuel pressure regulator, leaky injector, pump check valve, leak in the coupler between the pump and the hanger.

 

[tony42]

If you have pressure the pump is priming. You have a leak somewhere. Could be fuel pressure regulator, leaky injector, pump check valve, leak in the coupler between the pump and the hanger.

No prime sound from pump pressure is just for a sec then drop to o

 

[mikestertwo]

No prime sound from pump pressure is just for a sec then drop to o

You may not be explaining the problem correctly. If the pressure goes to 45psi when the key is first turned on then the pump is priming. It only primes for a couple of seconds when the key is first turned on. If the pressure drops immediately then there is a leak somewhere. Does the pump run when you apply +12V to the grey wire located behind the alternator? Does the car start?

 

[tony42]

no start cranks then makes a poof sound have not run 12v to pump

 

[NY_GN]

Just went thru something like this last week with new pump. Check the hose on the sending unit to the pump and make sure its snug.

 

[rag231]

At least you have a fuel pressure gauge to help diagnose the issue. Does the gauge do a slow gradual fall to 0 or is it truly instant? Once it goes back to zero , if you turned the key off and back on will the pressure jump back up to 45? I would start at the fuel pump also and make sure that every thing there is OK. If it is a common pump see if you can borrow ( someone's spare) or purchase another depending on age, parts do wear. Same goes for your injectors, send them to chuck leeper. ( Cody Motorsports) for a good clean and position reference to rule them out of the issue. Don't forget about the fuel filter and depending on the fuel pressure regulator the diaphragm can fail ( some can be rebuilt).

Fuel pump
Fuel filter
Fuel injectors
Fuel pressure regulator
Consider it spring cleaning of your fuel system.

 

[tony42]

Yes intant to 0 thank will check all

 

[earlbrown]

If it's instant my guess is the rubber hose inside the tank (or that stupid stock 'pulsator') has given up.

If the pump was installed in the last year or so and didn't get a 30R10 hose inside the tank, that is defiantly my guess.

 

[tony42]

new pump new tank not sure about that hose 30r10

 

[earlbrown]

30R10 is fuel hose that's rated for both high pressure (fuel injection) AND fuel submersion.

30R9 and below will fail approximately 100% of the time.


The really bad part is no parts stores stock it. And if you ask them for either '30R10' or 'high pressure fuel line rated for submersion', odds are they will look at you like there's an arm growing out of your forehead.

 

[tony42]

At least you have a fuel pressure gauge to help diagnose the issue. Does the gauge do a slow gradual fall to 0 or is it truly instant? Once it goes back to zero , if you turned the key off and back on will the pressure jump back up to 45? I would start at the fuel pump also and make sure that every thing there is OK. If it is a common pump see if you can borrow ( someone's spare) or purchase another depending on age, parts do wear. Same goes for your injectors, send them to chuck leeper. ( Cody Motorsports) for a good clean and position reference to rule them out of the issue. Don't forget about the fuel filter and depending on the fuel pressure regulator the diaphragm can fail ( some can be rebuilt).

Fuel pump
Fuel filter
Fuel injectors
Fuel pressure regulator
Consider it spring cleaning of your fuel system.

New 60 injector new filter new regulator n pump last year .n yes on second turn key psi up 45 then instant drop to zero

 

[Pronto]

Time to drop the tank and look at everything.