So this has happened to me twice now. 79 F-150 with a 400. I will be working on my pickup and start it up a couple times to move it around and what not and then all of a sudden it won't start. I pull a plug wire and there is no spark. My MSD box is working and the coil is firing and the distributor is turning... Any idea what could be causing this? The engine won't even attempt to turn over but if I leave it alone for an hour or so, it will fire right up like nothing was ever wrong... I'm stumped!

 

Just an idea but could it be the voltage regulator? or maybe ignition module overheating? My truck wasn't running here and there for a couple weeks and I took the regulator off cleaned the grounds and it fired right up. As I said just a thought.

 

I can try swapping out the regulator next time it happens, but i don't have an ignition module... I replaced it with an MSD unit

 

Ah see I'm not familiar with MSD units I don't know what they consist of. Thanks for the heads up.

 

If the coil is firing then it has to be between there and the plugs, bad connection on coil wire to cap, cap itself, rotor, or wires. Is it an MSD distributer?

 

Stocky dizzy, msd wires, coil, and spark box. All are almost brand new

 

So I started it up and drove downtown tonight and everything was running perfect. Went inside a place for supper and came out an hour later and she fired up and died right away and won't start now. It will sputter every once in a while when I am cranking but it won't catch. I went back 2 hours later and it fired up again but died right away. It's getting plenty of fuel so I don't know what's going on. It seems like the longer it sits the more it tries to start. Worse part is is that I am taking this pickup home from college because it is spring break. That's a 300 mile drive and my pickup is stranded downtown. Bummer!!!

 

almost sounds like its flooding. what kind of carb? how did ya check the spark plug? pull it out, put the wire back on, hold the electrode to a good ground, then have someone crank the motor. if no spark sounds like the distributer needs adjusted or replaced. check the points, adjust the gap, etc. just might cure the prob.

 

Have you tested the plug wires for continuity/resistance and double-checked the firing order?

 

Well I bit the bullet and dropped in an MSD 8477 distributor and that solved the problem! It was an expensive fix at $340 but my pickup has never started as good as it does now!