Engine cranks but does not start?

1995 FORD MUSTANG
225,000 MILES • 5.0L • V8 • 2WD • MANUAL
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BLAZ85
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  • 54 POSTS
The vehicle belongs to my son who has owned it for about 20 years. It is not driven a lot maybe twice weekly on short trips as he has several other vehicles.

A little background, the last time he drove it, it had multiple misfires anytime it was accelerated even modestly. A problem it didn't have when he drove it a few days earlier. When this occurred, he returned the vehicle back home and used another vehicle for the trip.

Today he went to check what might have caused the misfires as they seemed to be ignition related. When he tried to start it, it would crank over robustly but not start. It has a fuel pressure regulator with a permanent gauge and fuel pressure was right on specification. He then noticed a "nest" of pine needles (he lives in a rural area) on the intake manifold below the plenum and near the firewall. We are not sure, but we think that the rodent who built the nest may have chewed the ignition wire going the coil causing the no start. I have not been to his home to see if we have power to the coil, but I am betting we do not.

What we need is an ignition wiring diagram so if power is not present, we can start searching for the damaged wire.
If you could provide this diagram we would appreciate it.

Thank you in advance for your reply and for all the help you have been in the past!!
May 18, 2024 at 3:09 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
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Hi,

I have to agree with you. It does sound like some wires were chewed on.

As far as the wiring schematic, I attached the entire powertrain management schematic which is 4 pages long. I highlighted the wiring related to the ignition could for you. Note that I had to cut each page in half to make it readable, but I did overlap them so you can follow from one to the next.

Let me know what you find.

Take care,

Joe

See pics below.
May 19, 2024 at 12:37 PM
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BLAZ85
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Thank you for the wiring diagram, it was just what was needed.
We finally go to look at the vehicle. We could find no evidence that the rodent chewed any of the wiring. Checked power to the coil, we had 12V. As the engine was cranking, the tachometer would rise slightly so we had a signal from the pick-up coil. Our next thought was the ignition control module which was the original 1995 module. We replaced it but still no start. The vehicle has a MSD coil so we replaced it with the original coil which was known to be good. Still no start. Just out of curiosity, we tried another coil wire. The vehicle started immediately. We went ahead and replaced the entire wire set as it was still under warranty. The outside of the defective coil wire looked good and there was no corrosion on either terminal, We suppose it just failed internally.
Anyway the vehicle is running strong again. Thank you again for you help on this problem and others in the past. You guys are the greatest!!
May 27, 2024 at 3:10 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
Wow, thanks for that update. It's unbelievable how things can trick us. LOL

Regardless, I'm glad it's running again.

Take care and feel free to come back anytime in the future.

Joe
May 28, 2024 at 12:20 PM
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