cranks but wont start | Ford Explorer Forums - Serious Explorations

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cranks but wont start


February 22, 2010
Reaction score
City, State
Davie, FL
Year, Model & Trim Level
'91 XLT

My 91 explorer wont start after filling the tank the other day. I filled it, turned the key, and the engine wouldnt even turn. It was making a sound like there was an obstruction stopping the flywheel or something. I kept trying, and finally after like 5 min of cycling the key the engine started cranking and turned over. I got home, turned off the engine, tried turning it over again, and the same thing, it was acting like it was seized again or something. Again, after 5 min of cycling the key on and off, it started cranking again, but now will not turn over. I pulled the starter and turned the motor by hand and the flywheel is still intact. The flywheel does have a crack, im guessing somewhere by the crank/flywheel spacer, indicated by a slight ticking noise the engine makes when running. im pretty sure i have fuel to the motor, i dont have a fuel guage but i loosened the valve on the fuel rail and cranked the engine and got a good amount to come out. I still need to check for spark, but i dont see how a no spark condition can stop the engine from turning. Any ideas?


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No spark means that the fuel that is being pumped into the engine is not being burned. Once the cylinder is full it will hydrolock. Fix the spark issue and the lock problem will go away.

im going to go check for spark right now. i will post results shortly

so i pulled a plug, stuck it in the wire, and grounded it on the engine while having someone crank. it was pitch black, and I saw nothing. So I guess its narrowed down to spark issues. What to do now? Should I just replace the crank sensor? How can I check it?

It could be the crank sensor. You could have a bad coil, ignition control module, etc. Has the engine thrown any trouble codes?

havent had a cel come up on the dash at all. Have not scanned for codes, guess I should see if someone can loan me their scan tool.

havent gotten a scan tool yet, but I did a couple electrical tests. I found only 0.3v when checking voltage on the crank sensor harness with the key on. The haynes manual says it should be around 1.5v. Also my ground battery cable is very corroded, Im wondering if that is what is causing all of this?

autozone does free code reads. but yeah it prob the crank position sensor, coil pack, or bad wires. cant see all wires going out at once tho. as far as not wanting to turn over it could be a bad starter or lose or corroded wires to and from batt to starter. corrosion can stop you right in yur tracks.

his bad ground at the battery could cause it too. putting that extra resistance in the electrical system is basically the same as having a dead battery. Clean up that ground and see what happens, but a bad battery connection can cause a no start/no crank condition.

Ok, so I replaced the ground cable, but it made no difference. I still only have like 0.2v at the crank sensor harness. I checked continuity between the icm harness and crank sensor harness and it's good. Bad icm? Also, I was about to scan the ECM for codes, but I can't find the diagnostic port.

Diagnostic port is under the hood, passenger side, between the power distribution box and the heater fan. If it's been a while since it's been accessed, it may be tucked down inside the wires.

Bad ICM is a possibility, I'd probably start by checking power and ground to the ICM.

Thanks a lot, ill be checking shortly

ok, so i found a working ignition coil and icm to put in to see if it would start or at least give me SOME spark. Absolutely nothing. I have power and ground to the icm, but only 2 volts. is there supposed to be more than that at the harness for the icm? I still havent found the diagnostic port

The red wire going to the ICM should have +12 V. That red wire originates at the EEC relay and feeds power to several components in the engine management system (including the PCM). Is there + 12 V at other components fed by that red wire?

am getting 12 v at only the coil. I put a new eec relay, still not turning over. Im ready to just buy a new PCM. I am seeing used ones on ebay for cheap, anyone had any luck with these?

got it running, it was the relay, I forgot to put the fuse back in the power distribution box from before, and once i did, i could hear the relay click again, which it wasnt doing before. thanks for everyones help. cheers

my 91 ex will crank but no spark same problem. Would it be best to start with the relay or the crank sensor?

I guess I would first check for 12 volts at the harness for the crank sensor, with the ignition on.

Sorry, but it won't be 12 volts, it's been a while since I diagnosed my ex. A service manual will tell u the right voltages for the different harnesses. U should be getting 12 volts at the positive pin on the icm harness.

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i got sensor didnt end up being the problem! i wasnt quite sure where to check voltage from the sensors plug?