Mechanics

CHEVROLET TRUCK SPARK PROBLEM

1980 Chevrolet Truck • 300,968 miles

Grounding issue. 4 speed manual truck

need help fixing it
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Danielroach13
October 27, 2012.




Do you have a question? What kind of answer are you hoping for? You have to provide at least a hint of detail. What circuit? What symptom? What have you checked? You don't need help fixing anything yet. You need help describing the problem.

Caradiodoc
Oct 27, 2012.
Ive checked the circuits, the spark plugs, all the wiring. The altunater. Runs but not good enough to drive. Its not getting the spark it beeds to run and stay running. Grounding issue
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Tiny
Danielroach13
Oct 28, 2012.
Well, I'm in pain. Can you diagnose the cause from that description?

What exactly do you think is not grounded? Why are you even looking at the generator if you think there is a spark problem, and if it's a spark problem, how can it run at all?

First of all, you should have the High Energy Ignition (HEI) system with the really big distributor cap. Those put out a real lot of spark voltage. When there is a problem it almost always causes no spark and a no-start condition. Those systems DO have repair parts easily available but they were originally meant to be replaced as an assembly. If you think there's a spark problem, replace the distributor. Never remove a spark plug wire with this system while the engine is rotating. They put out so much voltage that if the spark can't get to ground through the spark plug, it WILL find an alternate path and that is usually through the rotor. That is called "punch through" and leaves a carbon track behind. From then on that will be the easiest path for current to flow through so it will go there instead of to the spark plugs. The rotor will be shorted and will have to be replaced.

If the engine idles okay but cuts out when you raise the speed, suspect a broken wire on the pickup coil around the distributor's shaft. You can identify that by disconnecting the vacuum hose at the distributor and plugging it. That will prevent the vacuum advance from turning that coil and flexing the wires.

Check for vacuum leaks too. That will affect how much fuel is drawn in from the carburetor and will cause a lean fuel / air mixture. That results in hesitation and stumbling when accelerating.

Caradiodoc
Oct 30, 2012.

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