Ok,
Fuel pressure is 42-46 PSI while running. When shutdown the fuel pressure goes from 40 psi to 15-20 psi within 20 minutes. Probably the reason for my hard starts. How do you troubleshoot the fuel pump check valve, fuel pressure regulator, or leaky injectors? Also, would this fuel pressure problem also be my shudder/hesitation feel when slowly accelerating, as in traffic?

Thanks in advance,
Hawaii 5.0
88 Trans Am WS6
5.0 TPI

 

From what you have listed, everything is fine with the fuel system. Bleed down is normal and from the time period you listed I don't see a problem. If it runs rough at start up, and blows some smoke, it may be leaky valve seals.

------------------
Pat McGrath '89 Formula LB9, T-5

 

H5-0,

Your fuel pressure may drop after the pump is shut down, and a certain percentage is acceptable. You can isolate the source of the leakage by blocking the fuel lines to/from the pump and tank.

A leaking FPR will allow pressure to bleed through the valve disc and back to the tank through the return fuel line. A failing check valve will allow pressure to bleed back through the pump itself via the fuel delivery line. Leaky injectors will allow fuel to leak through and will do so regardless of the FRP or pump condition.

If the return line is blocked (clamped) so that no fuel can return from the regulator and the fuel pressure still drops, the regulator is not at fault. Either the pump is leaking back through the check valves or one or more of the injectors are leaking.

If the return and delivery lines are blocked and pressure still drops, there is nothing left but leaking injectors or external fuel leaks around the injectors or regulator.

Good luck. If you find leaking injectors, check with Cruzin' Performance for service.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader