Fuel Pressure Drops Rapidly after turning off car

[bsdlinux]

Just like the subject says. I have a fuel gauge hooked up. Runs about 38-39 ish @ idle. Once the car is turned off the pressure goes to 20 within seconds and almost 0 within minutes.

Ok. I've read on how to troubleshoot the three things stuck injector, bad regulator or check valve. I've pretty much ruled out that its an injector so the question is about the checkvalve or regulator ( once checked )and what actual problems will occur.

Like I said before I have a hood mounted mechanical gauge and the fuel pressure will track perfectly with boost, no problems there.

So assuming its the check valve or regulator are they any problems associated with these as far as running the car other than the fact the fuel pressure dropping off immediately after shutoff??

 

[turbofrank]

Harder starting
It is easier to swap fpr first.

 

[boostingbuick]

Sounds like the check ball in the pump has failed. Time to upgrade that pump.

 

[TurboMonte 2]

Sounds like the check ball in the pump has failed. Time to upgrade that pump.

I would second this probability,--> Pinch-closed (vice grips) the rubber portion of fuel supply line just before/after/as shutting down engine & see improvement in holding pressure with time. Major improvement in pressure holding time-profile will point to bad ck valve/ball in pump...

 

[RUQWKNF27]

Does your fuel psi on the gauge jump around @ idle say 2-3 lbs back an forth?? Iwould change reg. first..

 

[bsdlinux]

Does your fuel psi on the gauge jump around @ idle say 2-3 lbs back an forth?? Iwould change reg. first..

Well the regulator is 6 months old. No the pressure looks to be dead nuts on all the time, no needle moving etc...

 

[RUQWKNF27]

found the problem yet???

 

[bsdlinux]

found the problem yet???

Well Like I said before, it has to be either the check ball in the pump or the regulator. i haven't tested for those yet but maybe this weekend. I was more worried about drivability issues until I get it fixed since this is my daily driver.

 

[Turbo1dr]

I've only replaced a handful of regulators that caused pressure drop and many more fuel pumps.

 

[RUQWKNF27]

My friend is having the same problem. Last night we put 3 differnt FPR's on his car an the fuel PSI still dropped. His goes from like 38 psito 30 psi with in min's.. I finally pulled out the dipstick an I swear I could smeel the sweet smell of Vp 116 on it. So guess it has a leaking injector some where. How did you rule out which one it is?? How did you do it??

 

[Mark E.]

There is always the posibilty of a loose connection in the tank.

Any smell of gas at the charcoal cannister?

A loose connection on top of the pump can spray the vent tube in the tank and send gas to the cannister.

Just throwing that out there.

Good Luck