About a week ago I did a fuel pressure test and it was leaking down pretty fast so I ended up taking the intake plenum off only too find the spider injectors or actually i think it was the FPR leaking . So i replaced it and did the test again and it didn't leak down as fast but still leaked down. Is there a check valve in the fuel pump that could go bad or even the pump it self. I can answer any other questions you might have but I don't see anywhere were im losing gas so Its got to be that pump if I dont have a leak in the plenum right

 

Yes, there is a check valve in the fuel pump module. What was the pressure and did it hold above 55psi for at least 10 minutes?

 

key on 60 psi, then in ten minutes 50, and i just replaced the spider as i said earlier and their is no sign of a leak anywhere. But it does not go below 10 psi if i let it sit for a while.

 

Probably the check valve in the pump. To confirm it, you need to isolate the pump from the rest of the system. This is done at the fuel filter by modifying the fuel pressure tester so fuel flow ends at the filter, (same procedure for checking maximum output pressure). Pressure must be 73psi to 108psi and must remain above 55psi for 10 minutes after the pump shuts off.

 

So if the pump is isolated from the system and it leaks down past 55 in 10 minutes the pumps bad.

 

The most likely place to leak is the check valve in the pump however, if the "accordian" style hose between the pump and the module housing leaks, it will also indicate a leak on the pressure tester. Either way, the tank needs to come down and the module removed from the tank to pinpoint the leak. If the accordian hose is good, and the clamps are tight, the pump needs replacement.

 

Thanx you have been a big help to a lost cause! Ill let you know what I find.