fuel pressure? key on, engine off

thisguy1985

Member
could someone tell me what the fuel pressure with the key on/engine off is?
i dont have a proper screw on test gauge, just a homemade one that fits on to the out port of the fuel filter, and it only reading about 25psi.
 

Texan

Well-Known Member
I believe that the pressure at the fuel rail should be around 50 psi. I think that your problem might be because you lost the
pressure in the line when you unhooked the outlet of the filter, When you turn the key on the fuel pump is only activated
for a short amount time.

You might try turning the key on 3 or 4 times and see if there is a increase.
 
OP
OP
thisguy1985

thisguy1985

Member
I did try turning the key a few times but it didnt move past 25psi. im getting the p0171 code and from reading on here i found that low fuel pressure can cause it, i replaced the filter and a bunch of other stuff related to the code but cant get rid of it. so im thinking the pump is on its way out.
 

bobdec

Well-Known Member
I own one of these, a must tool box addition for fuel injection cars... http://www.harborfreight.com/fuel-injection-pump-tester-92699.html . Not the best out there, but good for DIY occasional use and lending to family and friends..

EDIT..
Just noticed your in Canada, should be something similar available locally.. Most auto parts stores rent tools.. Also as stated, since there is no air in the fuel lines to compress, it only takes a few drops of fuel leaking out through the check valve in the pump, or your hookup to drop pressure. And remember checking just after the filter you are only checking the pump, not the regulator. I'd get a gauge on the test point, maybe find one with a hose long enough to tape to the windshield while running under loads. Replacing the pump costs enough money OR work DIY to warrant investing $$ and time into a good diagnostic test.
 
OP
OP
thisguy1985

thisguy1985

Member


i took this line off, made sure my pressure tester was on the filter tight (wasnt leaking) turned the key a few times and im only getting 25psi.
i just tested the FPR by taking the vac line off of it and waiting to see if gas would come out (it didn't) so im assuming that good.
am i supposed to test the fuel pressure with the engine running to get the normal 50psi reading?

thanks for all the advise btw
 

Texan

Well-Known Member
There should never be gas coming out of the vacuum port on the FPR. Does the engine run? You should check the fuel pressure
at the test port on the fuel rail with the engine running. I do not remember the exact number, but it should be around 50 psi.
If you replaced the filter, it may be the pump that is the problem.
 
OP
OP
thisguy1985

thisguy1985

Member
yes it runs.
i dont think there is a test port on the fuel rail on the 04's, in the pic i posted the finger is touching the test port.


Texan said:
There should never be gas coming out of the vacuum port on the FPR.
i know but if the fpr was faulty there would be small amount of gas come out of the fpr with the engine running. right?
 

cart7881

Member
The 2004 Service Manual specs call for 50-57 psi fuel pressure at the filter service port, with ignition on and engine off.
 

Staff online

Forum statistics

Threads
18,777
Messages
569,724
Members
11,413
Latest member
Btm88tc

Staff online

Top Bottom