As soon as shut my car off it loses fuel pressure fast.when I go to start it again I have prime the fuel pump twice before i can start it.As far as i know I thought it was supposed to hold pressure for while before it starts lose pressure.Car runs fine w/no issues.its 98 Hb.stock fuel pump.any thoughts on what it could be?

 

my thoughts are the frp

 

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X2! I have seen a number of FPR's go bad and even new ones not working right from the get go. You have a stock fuel pump but have you upgraded to a after market regulator. I have had a number of diferent regulators on my car and by far the best I have seen and currently have if the Aermotive one. I have had the AEM and the B&M before and didn't have graet sucess with them. Get your self a good FPR and a Walbro 255 for sure. Are you boosted? How do you know that you are losing pressure after you shut the car off?

 

Well I do have a B&M Fpr,stock fuel pump.I noticed a while back but it wasnt really doing what its doing now.I have an LS/Vtec.the fuel pressure goes almost instanly after I shut the car off.I just look at my fuel pressure gauge and just watch go down.Looks like I'm going shopping Thanks for the replies!

 

back from the dead.

this same thing is happening to me. the part that bothers me the most is that i need to prime the car a couple times before if gets back up to operating pressure.

JDM-EJ698- did u ever get this problem resolved? I'm using an AEM Universal FPR.

 

change the fuel pump mine did this but also was a bitch to start in really cold weather -20 c or colder the fuel pump would not kick on and i would have to jump it to straight battery power

 

change pump and strainer

 

Ps it works great now and even has better pick up past 100mph hehehe and the instant throttle response is back when trying to take off

 

Well I upgraded Injectors to RC 310 and a walbro fuel pump.but it still does it just not as bad.I kinda just gave up and garaged the car.

 

What computer system are you running in your car?

 

Pressure bleeding down from the fuel rail could be a few things.

1)Check valve in the pump no longer functioning.
2) Fuel pressure regulator stuck open or diaphram leaking (possibly causing a rich condition aswell)
3)Injector(s) leaking.

If theres rubber fuel lines, you can try a couple things to pinpoint your problem. I'm assuming your fuel pressure is being measured from the rail.

Try pinching off the return line from the fuel pressure regulator. Turn key to prime pump. Still bleeding down? Either injectors or fuel pump.

Try pinching off the fuel inlet hose. Still loosing pressure? Check valve in pump is stuck open.

You eliminate the fuel pressure regulater and pump, then its probably leaking injectors. I suspect its one of the other two though. You would probably have heavy carbon build up in your intake/ backside of the throttle body if your injectors are the cause.

Hope this helps. Goodluck

 

facing same issue, been a month. have to prime it like 8 times to start engine. replaced fuel pump twice. there is a fuel filter in the black part of fuel sending unit , the fuel pump goes inside of it. basically the plastic canister the pump goes into. change out the entire fuel sending unit, save the pump if it's good. I believe thats where the internal leak is coming from. will go to junkyard next week to scavenge a new sending unit to test.