Hi.
Has anyone followed the electrical path from the coil to the plugs? Quatruple-checked for good grounds?

I would post this to the forum, if you haven't already. Probably get a lot more ideas there.

Hi Jeepwalker;

I'm helping a friend with his 92 Cherokee. The car
runs fine on starter fluid down the throat of the carb. We have replaced the ballast resistor relay, the auto shutdown relay, and the fuel pump relay.
We have replaced the O2 sensor, the air temp sensor, the throttle position sensor, no help. I checked the output voltage from the Map sensor, its 4.7V so that's okay, and that also says the power to the other sensors is okay. When we turn on the key, we get a very short (~0.1 sec) pulse on the output of the shutdown relay that sends power to the injectors. The dark blue/yellow wire from the computer that controls that relay sits at 12.2V, indicating it does not want the fuel pump on.

What else do I need to check in the diagnostic procedure to find out what signal does the computer think is out of spec and thus must prohibit
running?

You knowledgeable help is greatly appreciated.

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