Hello All,

I am a new member from Idaho and just wanted to share with everyone what problem I had and how I repaired it just in case someone else has the same issue. I gleaned much knowledge from folks on this forum (THANK YOU!) so I am just wanting to give back a bit.

Truck: 1979 F-250 4x4 with 351 Modified 5.8L engine

Original Problem: Running fine one day and would not start on the next day. The engine would crank but would not catch or run.

Troubleshooting Procedures:

1) Checked spark by removing spark plug, cranking and checking for spark GOOD

2) Removed and cleaned fuel filter and checked carburator. Fuel pump pumping fuel into the filter and both jets pumping OK. Not a fuel issue. Yes, it was fresh fuel as well.

3) Has new distributor cap, rotor and spark plug wires. Removed the cap anyway to check for rotor revolution. GOOD. No loose connections. Checked magnetic pickup by using voltmeter. Attached meter leads to orange and purple wires at the Ignition Control Module, set meter to AC volts and got 1 VAC when I cranked the engine. Magnetic pickup good. Distributor OK.

4) Checked ignition coil windings with an ohmeter. Got normal resistance on the primary and secondary windings. Coil seems OK.

5) Suspected Ignition Control Module at this point. Replaced with a new one. Still have the same problem.

6)My thinking is that it could be weak ignition coil or a wiring issue at this point. Cheaper to check wires. Checked wires from the secondary of the ignition coil (white and red wires) to the Ignition Control Module. White wire had .4 ohms.GOOD Red wire had 13.7 ohms BAD. Signal was getting attenuated between the secondary of the ignition coil to the Ignition Control Module. I replaced the wire with a new 12 gauge wire and my baby fired right up.

I did not replace all the wires yet but I know that it will be wise to do so since the other wires are 37-years old as well and I could experience deja vu all over again if I don't.

The lesson learned here is NEVER to think just because your truck runs good one day and doesn't the next that it can't be a wiring issue. It CAN my Ford brothers and sisters!

Again, MANY THANKS to the friendly folks on this forum. I could not have found this problem without you!

 

Glad to hear you got it figured out and thanks for the troubleshooting rundown.

 

Thank you kindly for sharing that with us; it may come in handy.