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1994 ranger 4.0. Cranks good, no start, no spark, 50 psi fuel pressure. Heres the odd thing. Fuel pump runs, even when relay removed. injectors pulse. No ground on fuel pump relay. Tried to pull codes with Zeus. No com with Ecm. I have sent ecm to be repaired. Anyone ever seen a fuel pump run withthout the relay.
I've never seen it before nor do I care too:huh: but looking at the diagram it looks to me like the fuel pump relay on pin 87 (dkgreen/yellow) also feeds back to the PCM on pin8 of the PCM. If it was me, I would pull the relay, check voltage on pin 87. If I got voltage with the relay pulled I would go back to the PCM. I'm thinking you might have a short, but that may be a place to start.
Just dawned on me in the rest of your post that you can't communicate with the PCM with the Zeus. Pin 87 connects straight back to the PCM. Not to be a downer, but if you pull the FPR and have power on pin 87, It could be possible that your dealing with a fried PCM. Make sure you do all the checks on the PCM before you condemn it though. Sorry bro.
Sorry took so long to post fix. Found a reman PCM. Plug and play. Truck ran great. Customer is back this week needing head gaskets. Gotta love a 4.0. Thanks Dave for the input. Also had a different 94 range come in with some issue. Pulled ecm sent it to sia electronics in IL they fixed it right up. Must be common in this year model.
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