problem starting jimmy

[Zeph]

Hi there, I work at a service station and we are working on a 2002 jimmy 4.3l.

Customer says that after the vehicle sits for a while (1 or 2 days), he has trouble starting the car. It will turn over - but just crank and crank. He said that it will start if he pushes the accell pedal down eventually it will start. Our mechanics said the fuel pump is working. Any hints to point us in the right direction would really help thanks.

[GM-Tech]

Put a fuel gauge on it and see how long it holds pressure when you shut the engine off. If it drops to zero pretty quickly, there's your answer.

 

While the fuel pump may be working and putting out the correct pressure, if the check valve in the pump doesn't seal, the fuel line will drain back to the tank. Then, when you go to start it after it sits a while, the pump first has to fill up the entire fuel line, then build pressure, before it will start. This takes a little while. The fact that the customer pushes the pedal down and it starts is probably only a coincidence. Tell him to scratch his head while attempting to start it and it'll probably eventually start then too. Doesn't mean the head scratching had anything to do with it.

[Zeph]

Thanks for the help GM-Tech! I'll let you know if thats what the problem is