NO-START WOES - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

joelsford · 02-28-2013, 11:31

Hello, Fordsters out there: I hope someone can help me. I'm working on a '97
explorer with 4.0 sohc. It will crank but won't start. This is what I've checked
so far: cam position sensor, crank sensor (after verifying supply voltage to ignition module). According to the manual I'm using, if you disconnect the cam position sensor plug and turn the key on, there should be 1.5 volts present at that plug: it's missing. I checked the connector at the pcm (wiring diagram available) and all dc voltages and ground connections appear good: there were no broken wires between the cam and crank position sensor plugs and the pcm connector, yet the 1.5 volts is missing. I bought another pcm and tried that. Still nothing!!! ANY IDEAS, ANYONE??!! By the way, this started out as an intermittent problem. The owner would complain of the no-start condition, then, after the vehicle would sit for a few days, it would start right up and run fine for a little while (longest period about two weeks) and then not start again.

**CatSkinner** · 02-28-2013, 17:30

Any codes? I'm assuming so since your chasing the crank and cam.

joelsford · 03-02-2013, 15:48

No, and that's another puzzling aspect of this whole thing. You would expect to find codes if info wasn't being Rxed/Txed. There's gotta be something I'm
not catching, and I hope to find out what it is. I'm open for any suggestions.

**Bert** · 03-02-2013, 18:34

Have you checked fuel pressure? Is it the ignition that's failing?

joelsford · 03-02-2013, 20:13

No, the ignition system is ok (as far as I've tested): the coil pack is getting 12V. It's not getting any trigger pulses from the ecm. As far as fuel pressure,
the ecm turns the pump on initially at key-on, which it's supposed to do, but during cranking there's no fuel pump turn-on from the ecm, which, according to the service info I have, needs to see pulses from the cam sensor to turn the fuel pump on when cranking. There's also supposed to be a small voltage to the cam and crank sensors from the ecm, but this voltage is missing, which made me think the ecm was bad, but I installed another unit and still no luck.

**CatSkinner** · 03-03-2013, 08:26

What you're describing sounds like a faulty switch to me, I'd check the PCM power relay. You may have carbon build up or arcing damage to the internal contacts.

http://repairguide.autozone.com/znet...3f8021b98b.gif