78 turns over but won’t fire

Asked by Mar 25, 2018 at 10:54 AM about the 1978 Ford F-150

Question type: General

78 f150 with the 351m and I know that
everything is good I.e. carb, fuel filter,
battery, coil, plugs and wires, timing is set
tdc, dist. And rotor. Everything listed is new
and set up just for this truck and it has a
1/4 tank of premium non ethanol gas
please help me

4 Answers


Did you visually check for spark at the plugs, engine cranking? If no spark, did you check primary voltage at the ignition coil, key on, no crank, positive and negative leg, use a test light. If that checks out, use test light on negative side of coil, engine cranking, does the light pulse? If the answer is no, have to check ignition module. On some fords that tfi module is noted for problems. Could be other issues?

2 people found this helpful.

I’ll check it out and hopefully This’ll work


Yes, check the ignition module. Friend with 1977 Ford F150 had similar problem. The tfi had gone bad.

Did anyone ever figure out what the problem was here? I have a 78 also with the same engine and exact same problem.

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