Dad's 77 F-150 with the 400 is having ignition issues. I know these systems are fairly notrious for having issues but figured there is probably an expert on here. Symptoms are no start/no spark and then it gives one spark when you turn off the key (not release it from the start to the run position, when you shut the ignition off) and it will pop since the motor is flooded. I've read that the one fire at the end is standard duraspark workings. We've already ordered a new ignition module (duraspark box) for it and waiting for that to come in. Been trying to imagine what else it could be if that doesn't fix it. Only other thoughts I've had is the pickup in the distributor and maybe an ignition switch itself? Thoughts?
Ford Duraspark troubleshooting
- Thread starter nwjones18
- Start date
The small pickup sensor in the distributor is the likely reason.
Make sure there is power to the module and coil while cranking (not just with the key on). And I think the module must be bolted down and securely grounded for the system to work.
Yes you can ohm test the distributor sensor. Unplug the module and test end to end from the module plug so you are testing through the wiring as well.
Yes you can ohm test the distributor sensor. Unplug the module and test end to end from the module plug so you are testing through the wiring as well.
I doubt a store would keep that around to test 1 box every 15 years.
I grew up in that era and never saw the pickup in the distributer fail. Was always the box and guys carried a spare..
This is assuming that the timing chain is ok. If its slipped it too can cause weird sparks
- Joined
- Jun 26, 2023
- Messages
- 566
I always kept 2 spares. One backup, and a backup for the backup. Lol. Actually needed the 2nd one to make it home once. Used to snag OE Motorcraft boxes out of the jy, if you found a decent one you could get more mileage out of it than the cheap AZ Wells offerings of the day. Mid-late 90s/ early 00s.
You can replace the DuraSpark module with a GM HEI module, though many of those are of dubious quality as well these days. For good reliability, the HEI module should be mounted on a heat sink with heat transfer compound.
- Joined
- Jun 26, 2023
- Messages
- 566
My dad did this back 20 years ago in an 83 F150. Worked well, never gave him another ignition issue. Mainly just costs wiring supplies and a module.
It was the box.. Threw on a new one and it fired right up. Motorcraft was only $44 on Amazon.
Did you buy a spare?
Not yet.. But Dad said he was going to.. haha. The one that was in it was off brand and probably 20 years old so not a bad run.
I was voting on the box being bad. Glad you got it sorted out
