x944turbo

I noticed lately my fuel pressure has been dropping after i shut off the engine.

The gauge i have usually reads around 40psi at idle and goes up a few psi under revs. Once the car is shut off it will drop to 0 in about ten minutes. Is this normal or do i have a leak somewhere?

RajDatta

Could be a bad FPR, is it a factory unit or adjustable one?
Raj

zoltan944

hmmm.... 10 min may be a bit soon but definantly doesn't worry me

Cory9584

pull the vacuum hose off and check for gas, it could also be a leaky injector

quinnfiske

There is also a check valve at the fuel pump. They can get sticky and sick open. They are about $12 if I remember correctly.

SamGrant951

check valve, mine used to do the same thing...

xsboost90

mine does that- new injectors, regulator, gauge and fuel lines. Bet its the check valve bleeding off. No biggie just takes a crank to get the fuel back up to the rail.

philcav7

Doesn't the pump turn on with the key in the on position?
Wouldn't it pressurize before cranking, or does the DME control the signal to the pump?

Many cars you can hear the pump turn on with the key.

xsboost90

depends- if you turn the key on and then wait to crank - but usually i just put the key in and start cranking. Technically if you put the key in, turn it to the on postion, then crank it would build pressure before you crank yes.

philcav7

Thought so. I wait always wait to crank it from the on position. Not sure why, just one of my habits.

Spidey944

Mine leaks down too, but takes 2-3 hours to fully drop to zero. I'd say it's a very leaky injector, or the check valve as stated above. That's a pretty big/fast leakdown if you ask me.

wolfenstein

leaky injector or bad check valve, fuel pump only runs when you're turning the engine over or it's running

TurboTommy

Could also be the fuel rail leaking.
I had this once.
After turning the car off, sniff around if you can smell fuel.