Ignition problem. My '84 Chevy with HEI won't always start when hot. Wait a few minutes, it starts. What's UP?

Question

I'm thinking ignition module or the coil itself. Is there a way to check? Also maybe condensor. I know it's common. What's the most common failure? Thanks!!!

Answer 1

I'd replace the ignition module first. Those things go bad so much that I used to keep spares in my toolbox in case one went out while I was driving. They're not that expensive and aren't hard to replace.

Answer 2

It seems everyone is guessing or advising replacing this or that part. While that can usually resolve the problem it can become quite expensive if you don't get lucky right away. I have never been an advocate of the 'throw parts at it' method of troubleshooting. The repair manuals for that model will give you methods for checking the ignition coil and the distributor pickup coil with an ohm meter. The distributor ignition module can be removed with a phillips screwdriver and taken to an Oreillys Auto parts to be checked. The module has to be tested and retested until it is hot to see if it is failing at temp. Removing the entire distributor, unless you know what your doing, can get the timing so far off you'll need a mechanic to restore it. The repair manuals are available at most parts stores for around $20. I've done everything from tuneups to complete restorations on a variety of cars for 50+ years and won't mess with them without a book. I hate 'stabbing in the dark' at a problem. Good luck.

Answer 3

Ignition module failure is very common on this vehicle. The dielectric compound which is used under the base of the module dries out and the module loses contact with the
with the plate in the distributor.
Sometimes you can just clean everything and reapply the compound. This will reestablish the heat sink capabilities od the mounting base.
Of course if you have gone this far you may as well install a new module.

Answer 4

I have replaced a bunch of ignition modules in this type of car and situation. Heat can cause them to act like that. The coil ? Without proper diagnostic equipment it's a little hard for the average guy....BUT....you can look at the coil ....sides....the part you see when you take the 4 small screws out to take the cover off....is there a slight discoloration? Like a " lighter" area than the surrounding one....and look at the bottom of the coil that the spark actually comes out of....see if it looks Blue....if either one of these conditions exist...change the coil. Hope I helped.

Answer 5

Check for spark when it's hot and refusing to start. If it's absent that will at least be a starting point. No start when hot could be a number of things from a wire that loses contact up to a coil that shorts when hot. Try substituting parts is possible until the problem goes away, or take it to a mechanic.

Answer 6

If you have confirmed that this problem is ignition related pull the distributor cap and remove the ingnition module located at the base inside of the distributor. Clean the back and re install it with new heat sink compund on the metal back.

Answer 7

GM intense potential Ignition ( HEI ) have had module subject of their background. yet ...you reported once you hit a bump....could be the %.- Up Coil interior the distributor...it is the little white looking element that the distributor shaft is going down the middle of. in case you truck has a lot of miles it could prefer an entire new distributor. Rebuilts are straight forward and not that high priced and in many situations incorporate a %. up coil and module .

Answer 8

I'm thinking just like you having had an '83. The problem is most likely in the distributor unit. If I had it to do over again, I'd have gotten a completely separate distributor for my '83 that I knew was good (because I'd keep it as a spare). Then whenever you suspect a distributor problem, pop in the spare to prove it.

Answer 9

I would first try and eliminate the possibility of vapor lock. Try a tank of non-oxygenated high octane gasoline and see if this does the trick. If not, then have a mechanic run a diagnostic on it when very hot. This might pinpoint the problem.

Answer 10

I think thats called a saturated coil, there are improved coil designs avail, try one. Also, I would recommend getting a premium plug wire set from NAPA.

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