I thought I would introduce myself with a troubleshooting question. I have been waiting for the weather to get a little better for what I thought was going to be a simple fix but so far I haven't figured it out.
'91 YJ 4.0L with multi-port fuel injection.
I have a no-start. I noticed that the fuel pump doesn't come on for its usual two seconds when the ignition switch is first turned on.
I jumped the connectors at the fuel pump relay and the fuel pump turned on and I heard the fuel flowing through the lines.
Bought a new fuel pump relay and installed it but no dice.
I am not sure exactly what the auto shut down relay does but I replaced it with the relay I had just removed from the fuel pump position just to try it out. Still nothing.
I jumped the relay connectors again and cranked the engine with the fuel pump relay bypassed and the fuel pump operating. Still no start.
Removed a spark plug and the cylinder was dry.
Checked the fuel rail very unscientifically (stuck the test port with a screwdriver) and got lots of fuel out.
Sooo... I am thinking I have fuel to the fuel rail but the injectors are not getting a signal to open. I imagine the issue is related to the fact that I am not getting that two second run of the fuel pump on initial start-up.
I suppose I need to get a real shop manual...