Good morning-
the title says it all.
after sitting more that 4 hours, if i put a fuel gauge on the supply, i read 40 PSI ( not enough to start). running, the needle bounces all over the place so its hard to get a good reading. Spark is good
if i spray fuel into the open throttle body butterfly, the truck will start and run albeit rough.
i know i have a fuel issue.
Question #1 with the truck cold, what shoud the Key On Engine Off (KOEO) fuel pressure reading be?
i have this issue down to either fuel pump or regulator. i will replace the fuel filter this weekend to see if the pressure rises KOEOff
Question #2 i see the steel fuel return line out of the back of the plenum- which is the return line at the fuel tank?
i do not smell gas in the oil, but there is a slight odor if i open the throttle body which i expect is normal.
Question #3 based on this info, is this an indiacation the the spider and fuel nut is OK?

 

Key On - Engine Off -- 55-60psi
Pressure must remain above 55psi for 10 minutes after the pump shuts off.

The return line will always be the smaller of the two lines.

I would pull off the upper intake plenum and have a look for signs of a leak inside. You could also fashion up a fuel pump test rig for testing back at the fuel filter, dead-heading the pump to see how high the pressure goes there. Check out the Tech Article (DIY) section for some threads on the CPI fuel system as well as fuel pressure testing. The 96+ fuel system diagnosis thread has the info on what is necessary to dead-head the fuel pump.

 

Just an update- I replaced the fuel filter with no sucess.
I started the engine and again the pressure is around 50 PSI.
After pinching the return line the pressure held at 62 PSI. So I am thinking either the regulator is shot, or I have a leak under the intake plenum. I do not smell gas in the oil, nor do I have a strong odor of gas from the intake manifold. Am I correct is presuming the fuel pump is probably OK?