I'v been having all kinds of problems with my 92Z28, 305TPI. I connected a fuel pressure guage to the fuel rail and got 38 psi. I believe it should be 41 to 47. Is 38 low enough to matter. Car won't stay running when given any kind of throttle. TPS, IAC, MAP and other stuff seems to check out ok. Thanks for any help.

 

I also put a new FPR on. When I remove the vacume from the FPR the pressure goes up and the pressure also seems to go up when I give it some throttel but the engine also wants to stall.

 

Anyone have an idea?

 

Perhaps I misread your initial post, but I believe you stated that you could read 38 PSIG at the fuel rail with the engine running. If that is correct, your fuel pressure is fine. The factory specification is for a pressure of 37 PSIG running, ±3 PSIG. With the fuel pump running and engine off (or with the vacuum line removed from the FPR), the pressure should be 44 PSIG, ±3 PSIG.

If you are testing pressure with the engine off or vacuum line removed from the FPR, you may have a problem. You'll need to isolate the FPR and close the return line to the tank to determine if the problem is with the pump and filter, or with an FPR that is bleeding fuel back to the tank at too low a pressure. If pressure increases with the FPR fuel return line closed, the problem is likely the FPR. If the pressure does not increase with the FPR fuel return line closed, you may have a pump problem.

 

With the key on the fuel pressure builds up on the guage. If I just let it sit there and watch the pressure goes down slowly. If I pinch the feed line the pressure goes up. So what have I learned? I replaced the fuel pressure regulator yesterday.

 

Anyone have any idea's. The car will start and stay running. Runs a little rough. As soon as you give it any throttle it dies.

 

Fuel pressure at 38psi static is fine. What does the FP do when you blip the throttle? I'll bet the fuel pressure drops indicating a bad fuel pump or clogged filter

 

When I blip the throttle the pressure goes up, but the car wants to die. Could it be the injectors?

 

Whats the easiest and cheapest (without buying alot of test equipment) way to test the injectors?

 

When I spray carb cleaner into the upper plenum the car will throttle up and stay running and the fuel pressure guage will go down. Would that indicate a fuel pump that is maybe failing?