djmacc

Hi,

I have a hybrid setup. A GM computer in Jeep J10 with a Ford 460 engine. The computer and wire harness are out of a 91 camaro to give you an idea what generation EFI this is. Anyway my problem is that my fuel pump only runs when i turn the key to start the engine. The engine starts fine, runs a few seconds and dies and will only restart if I reset the key and listen for the pump to run then it will fire momentarily and stall. This setup has no crankshaft or cam sensors or oil pressure sensors to complicate the matter or even a fuel pump relay. So I am trying to figure out what tells the pump that the engine is running and to continue pumping? I have an external fuel pump and an MSD ignition if that helps. Thanks in advance for your thoughts.

Dan

Apeiron

The ECM needs reference pulses from the distributor before it will power the pump.

djmacc

Thanks, so it looks like I have to figure out which wire goes from the ignition system to the ecm to trigger it. In the mean time if I run 12volts direct can I cause any harm?

Apeiron

12v direct isn't going to do a thing, it needs to see pulses.

Six_Shooter

iTrader: (2)

The reference pulses are from the purple/white wire that connects between the dizzy and the ECM, there's no separate wire from th eengine/dizzy to the ECM to trigger the fuel pump relay signal.

You need a fuel pump relay to power the fuel pump, the ECM does not have a strong enough outputs to power the pump directly.

djmacc

Understood. Thanks for the info. I should be able to troubleshoot it from there.