DBN

iTrader: (6)

Has anyone had this problem? I am having a mysterious electrical problem. It is always upon start up with my 2000 C5. Sometimes when I turn the key to the on position I hear the fuel pump running and everything preparing for startup and then the car starts. But sometimes when I turn the key to the on position I don't hear any fuel pump and the car spins over but doesn't fire. I checked the yellow fuse next to the fuel pump relay and with the key on, it has voltage so I don't think is a problem with the ignition switch. I have had the collumn lock fixed. I replaced the fuel pump relay and this did not eliminate the problem. My next guess is to replace the pcm, as I reflash it alot. Could this be the problem or do you have any other suggestions? Thanks alot. Danny.

TAQuickness

iTrader: (28)

When it doesn't fire, what do you have to do to get it going?

WS6FirebirdTA00

iTrader: (33)

i wouldnt jump to the pcm. could be a bad pump or some sort of switch

custom 68

iTrader: (9)

cant you jump a couple wires to determine if the pump runs regardless of the pcm? I thought that was a common check..
Dave

mk3cn4

iTrader: (3)

It "might" be normal for the pump to not prime second or subsequent "ignition on" sequences if the pressure's still up.

I believe my 1993 Z would have a fuel pump prime on the first ignition-on, but subsequent ones right after wouldn't make the pump prime (the car would always start normally).

Just throwing it out there for someone to confirm, it "might" be normal for the pump to not prime every time (if the pressure's already up), and it might be unrelated.

Hooking up a guage to your fuelrail would tell you if pressure's up or not during cranking.

DBN

iTrader: (6)

Thanks for the comments guys. I can remove the fuel pump relay and jump across the leads to get the car to start but I can also wait for a period of time and it will also start without removing the relay. Since the relay is new, I assume it is not the relay itself. Any other suggestions?