351M ignition problems........

I have a 79 T-Bird with a 351M and Gremlins
I can't keep spark, I can be driving it and it will cut out, or I go to leave and it won't start no spark, but then it will work suddenly.
Replaced the coil, helped for a bit. Replaced my old distributor helped for a bit. ignition module yep worked for a bit, ignition switch is about 10 years old and I have put about 10,000 miles on the car in that time.

That was a copy of an old post I had on this problem. After looking into this further. Here is what I have found. I have spark in every cylinder on the driver side and none in #2 and #3 but #1 and #4 is very inconsistent. Checked it with another plug one wire at a time. FIGURE THAT OUT, swapped distributors again also.

I have no emissions on this hot rod, It will not even idle now for obvious reasons no can I put her in gear for the same reasons. Why would I lose one side and what can I check next? Keep in mind that this is also on a cold engine now while I have tested for spark this past time.

Thanks in advance,
Chris


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Have you checked your plug wires? And you have checked the brain box. Its on the side of the inner fender is it showing signs of melting on the back side of it sometimes you can see it running down from behind it. Cole

You didnt say if when you swapped teh distributors you also swapped the cap. If not take a look at the cap. I would also make sure all the engine grounds are clean and tight. The box on the fender could be bad, I dont know of any way to test it. We alway had a spare to try. The other things to look at is the connections to the distributor. I am assuming it is a TFM type distributor. Those had issues with the connectors.

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Chet

Idont know of any way to check the box either. Like Chet we kept one around to try with. Cole

are all grounds ok ? even grounds from engine to chassis and to body ? also check for goof full ground in ground wires in the ignition wiring

also make sure distrib housing has good strong ground as well.

just something to check, in which si required in order to have good strong ignition spark



good luck!!

I did swap my old module for kicks as a test, and no difference. I did replace the 1 engine ground I have and that didn't make a difference. Cap and rotor are new, I even tried the old cap to see if that helped, and still nothing. Getting frustrated here but really thankful for the ideas. Keep them coming!!!!!

Sounds like you have a corroded module harness or connector there, get out the ohmeter.

Again guys keep opinions coming, I will use an ohm meter to check things as I do think this will help, but am open to ideas. Problems like this are incredibly frustrating, but I guess this is why we are all Hot Rodders!!!!!!!!
Thanks,
Chris Deidrick

OK, so even though I am frustrated I did try a module off of a buddies car and again no difference. I have't gotten my hands on an ohm meter, but I developed a theory and I would like another opinion. TIMING CHAIN. The only reason I say that is when I did replace the distributor the first time, the problem basically went away. The problem came back after putting more miles on the car. Chain possibly stretched more then and finally jumped a gear perhaps. I can't explain the dead 1-4 cylinders but its just a thought. AGREE??????

Does that engine also have a crank sensor. Some systems did. If so you may want to take a look at it

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Chet

no crank sensor on this engine

Timing chain is not going to effect spark on only 2 cylinders. And you said before sometimes it would run great andthen just die. If the chain was bad it would never run great.
How ar you checking for spark at each cylinder. Did you actually pull the plugs and look at them.

As for grounds, thee should be one right from the battery terminal to the body. The large end of the cable should be bolted to teh engine both tight and clean, and there should be a ground from the block to the firewall, usually from the back of the head.

If you dont have these grounds in place, stop and fix them.

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Artificial Intelligence is no match for Natural Stupidity



Chet