No start...well sometime's

[dizzymac]

My 94 Jimmy 4.3 TBI does not always start, don't hear the fuel pump when it does not, do hear it if it does start, have cleaned harness connections and ground, no change, still starts intermittently.Put my sons Snap-On diagnostic on it came up with bad voltage for the CCP (carbon canister purge solenoid).
Everyone says fuel pump,but I would think if the pump was gone it would be totally gone. Any suggestion? Thanks.

 

[dyeager535]

That setup still use an oil pressure switch/relay setup for fuel? I assume yes, GM didn't like changing things.

Does it start eventually if you let it keep cranking? Oil pressure switch will bypass the fuel pump relay once oil pressure is high enough, so if it STILL doesn't start after prolonged continous cranking, then it's probably not that part of the circuit. You can force the pump to run by jumping two pins on the ALDL connector, but I can't recall which two, search on this board may net that answer. There is also a test lead on the fuel pump relay connector on some applications IIRC.

If you can't force the pump to run with those tests, then likely it IS bad, or something is wrong between the sending unit and the relays, but that's really only the one wire.

 

[dizzymac]

won't start if you keep cranking it, leave it alone for awhile and it will start, acts almost like a vapor lock. (if I had a man. pump). May try jumping the pump, if you see a mushroom cloud and hear a loud bang then you'll know I had the wrong terminals....lol