Yester day my 1997 4.0 died while driving. It seems to have no spark at all. I just replaced the coil today due to it having several cracks in it and nothing. Has new plugs cap rotor and wires. It is also reading empty on the gas gage while having fuel in it. When I turn the key I can hear the fuel pump running but it doesnt stop running idk if this is normal or not. Any ideas? Thank you I'm trying to avoid halling it to a dealer :/
It sound like something has gone wrong with the PCM. A couple of things may be causing it, one is the crank sensor and the other is either of the O2 sensors. The usual failure mode is the PCM will not do anything when one of these shorts out. What you have sounds like a partial failure. Does the check engine light come on for 3 seconds when you turn the switch to the on position? If not, the PCM is definitely malfunctioning.
It isn't and low fuel light comes one. Both o2 sensors are unplugged to rule that out. Where at is the pcm fuse? Not sure have seen a few diffrent thing. And should I just go ahead and change the crank sensor?
have u been wheeling lately? check for shorted wires near drive train. the fuse for pcm is in the power box under the hood. if its blown, the o2 wiring is suspect. the crank sensor is still suspect too unplug it before changing the fuse if fuse is blown.
I checked asd relay .ignition fuse fuel pump relay. Pcm fuse. Just went for runnining ones. Will check others tommarow. I believe it was still no check engine light when unhooked.
"It is also reading empty on the gas gage while having fuel in it. When I turn the key I can hear the fuel pump running but it doesnt stop running idk"
The fact that the fuel pump keeps running I think is key here. Since it is only supposed to prime and then stop, and given the strange other behavior, I vote for a short or bad ground somewhere.
If you're not getting a CEL lamp check from the PCM, the PCM is not working (assuming you know the light was working earlier). Since it is sending a ground to the fuel pump relay, it's not completely dead. You can reset it by disconnecting the negative battery cable. After you disconnect it, turn the ignition to start to discharge any residual voltage. Then, take the keys out and put them in your pocket. Then go out and clean your battery cables if you haven't done so lately and reconnect them.
As a long shot you can try swapping the ASD and fuel pump relays with the horn and intermittent wiper relays.
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