I have a 1981 ford motorhome that i just had a used 351m put in it. The motor home ran great for about an hour and another half dozen starts for short trips. I then had a spark problem and replaced the pickup coil. This seemed to fix the problem until it quit on me when driving and when i tried to start it, i found that it had no spark. I am wondering if I should try replacing the ignition coil, ignition module or if there could be some problem with the electronics in the steering column? The ingition switch does have an issue, that it needs to be manually turned from the start position to the run position after it has been started. Also when i was trying to get it going, it seemed that it would want to fire just as you were letting off of the key - turning it back from the start position...

 

Sounds like the module,when they go bad they will run untill it heats up and will shut off.

 

i have replaced the ignition module, ignition switch, pickup coil, ignition coil, pos battery cable. Still will sometimes start and sometimes not. It is currently sitting on the side of the road after running for about 10-15 mins then just shutting off dead - no sputtering... sat for 8-9hrs, still no spark.
What else can i look at/test/replace?
Could it be the wiring harness?
should i pick one up from a wreaker?
could the battery or alt be doing this?
Could it be an oil pressure switch doing this?

 

check the fusible link coming of the start solenoid also ignition wire going to coil

 

The two wire connector on the module is the power source for the ignition,one is keyed and the other is for when starting so see if they both are getting power when they should and if they are you could of gotten a defective new part and make sure there are no pinched wires due to the motor installation. Check the wires at the connector at the coil as I had those go bad and a no fire situation.

 

Pull the ingition wire off the solenoid and try starting it,I had solenoids go bad and short out the ignition.

 

I checked the power to the ignition coil - at first no power. I hooked a wire directly to the battery and still did not start. I took the wire off and checked, and now had power on both sides. I traced the power back to the module. I have not yet tried the rest as it started to pour on me... Hopefully I'll have a chance to soon before it gets towed...