What tells the coil to spark on a 1977 Ford with a 400 engine?

I have a new 400 engine in a 77 Ford pickup. For some reason the coil is acting up, I try to start it and it will turn over like it is not getting enough gas when it is getting gas, but will try and turn over as you are letting off the ignition. The coil will spark as you are letting off of the ignition after trying to start it. Why? We are having a hard time figuring this one out, can anyone help us?What tells the coil to spark on a 1977 Ford with a 400 engine?The distributor uses a magnetic pick up coil, not a hall effect switch. Connect an AC voltmeter to the 2 wires coming from it to check it's operation. You should get about a 1/2 volt AC reading while cranking the engine.

Check the wires to it at where they go into the pick up coil. They often break there from the constant flexing of the vacuum advance action. Even if the wires are good, the magnets can wear out after time as well. This will show up as a low or negligible AC signal.

A break in the wire could be intermittent before it becomes total. A resistance check while using a hand vacuum pump to operate the advance canister will usually catch a broken wire, even if the insulation is still intact.

If the pick up coil checks OK, it probably is the ignition control module (as DrCustom described it, size and location wise). Make sure you get one with the same color plastic plug where the wires come out of it, as the wiring changed from generation to generation of module, and which wire is for what changed from one to the next.

Also, these modules have to be grounded to work properly. Make sure it's bolted securely in place, and not all rusty there. It's a chassis ground through the mounting bolts.What tells the coil to spark on a 1977 Ford with a 400 engine?
Sounds as though the electronic ignition module is bad.. I believe that the type used back in '77 was called Duraspark and it will be a square aluminum box about 4"x4" and 1" thick mounted on the left fender skirt or possibly on the fender.. There is also a pick-up coil in the distributor that contribute to the process , but the symptoms sound as though the module has failed.



Hope this helpsWhat tells the coil to spark on a 1977 Ford with a 400 engine?This vehicle has a hall effect distributor with a pickup coil as the trigger, the spark signal is amplified by the ignition module. Replace the ignition module, it's cheap. Also check resistance on the pickup coil, they can also be a problem.What tells the coil to spark on a 1977 Ford with a 400 engine?
A new engine will run if it's timed and tuned correctly. It's so easy to get the distributor in 180 degrees wrong. Top dead center comes around twice and one of those times it's to fire cylinder number 1. The other time is when the valves are open on cylinder number one. Check it again and make sure both valves are closed on cylinder number one when you set the distributor pointing to fire that cylinder. Good luck.What tells the coil to spark on a 1977 Ford with a 400 engine?The days of old are gone, so unless one of us old timers gets on here and gives you the answer these kids will never figure it out, in fact I should just hang out and see if anyone has the answer, Hint it has nothing to do with your coil or distributor, I'll be back in awhile, check for an Edit.

What? the little tards gave me thumbs down? or was that you? I don't even know if I want to tell you the secret now. Its very simple. and cheap. you just need to know your old Fords, little dummies need to go back to there little ASE books and study some more, Oh wait! the ASE test wouldn't cover a 77 Ford these days, probably wouldn't even know what a starter solenoid looks like on a 77 Ford. or what the wires that went to them do. Uhh.. that was a hint.

OK before you start changing modules and pick up coils and god knows whatever else try jumping the 2 excite wires at the starter solenoid as in a piece of wire between the 2 while there still plugged in, them would be the 2 small ones, and try it agian, Ford has a better idea and someday there gonna build a car and a truck.