I hooked up a fuel pressure gauge to my car yesterday. I put the key on the "on position" and went to the gauge, it shot up to 35psi, then bled off very quickly. i started the car up, and it was at 34psi. I didn't take the vaccuum line off, but whatever. if i had a good fpr wouldn't it not bleed off?

 

The stock FPR should hold that pressure - the other end of the line should hold pressure via the pump. So your situation could be from a bad FPR or a bad pump, unfortunately.

By the way, the Aeromotive aftermarket FPR bleeds off pressure when the key's off, and my understanding is that folks manage to use it.

Dave

 

The pump should be putting out around 43psi with the vaccuum line off the FPR.

It's normal for some aftermarket FPRs to bleed down, like Dave said.

Mike

 

nah, this is the stock fpr

 

???

 

It could also be an injector hanging open. A quick way to check your FPR is to pull of the vaccum line and see if its wet. That will only tell you if its bad though, a dry one can also be bad. I think you may have to take the fuel rail out to change it. I had to take it out on my g/f's 97 V6 camaro.

 

Then is should hold the pressure. As noted above, the pressure can only bleed down if the diaphragm in the FPR leaks, the check valve in the fuel pump leaks, or the injectors leak. The FPR is easy to check... pull the vacuum line off and look for wet fuel. The injectors can be checked by pulling the rails and pressuring the fuel system. Its the pump that's hardest to diagnose, but if you rule out the other two, its likely the pump.

When you turn the key on, without starting the engine, the pressure should rise to at least 41psi. The acceptable range is 41-47psi.