komobu

Hi;

2001 GMC Jimmy with a 4.3. Sometimes when attempting to start vehicle, It will just crank but wont start. Fuel pressure is over 40lbs. Vehicle has spark. I thought it might be a security issue so I replaced the ignition wiring harness at the cylinder lock. Didnt help, it acts the same. If I go from "start" to "Off" several times, I can then usually get it to start and run. Also some times during cranking, you think it is gonna start and then nothing. Any idea whats going on?

Thanks

MDTAHOE

is the security light flashing? You say pressure is 40 but does it hold pressure when you turn the key off. Try to cycle the key on and off several times 5 or more before you crank it. If it starts right up then you are losing prime from lines so fuel is not there yet when you first crank.

komobu

Thanks for the help. The security light is not flashing. When I put the key in the run position (From Off) I can hear the fuel pump run for 2 seconds as expected. Checking the rail pressure, I have 40 lbs. If I shut the car off and then back on to re-energize the pump, I still only show 40 lbs. The pressure does not bleed off.

If I shoot starting fluid down the throttle body, it will start and remain running just fine. I saw on another board that it takes 65 lbs of pressure to start, but less fuel pressure to run. Since I only show 40 lbs, I will try replacing the fuel pump and see what happens.