Hitman's Pontiac Trans Am Forum
Trans Am Information => Trans Am Tech => Electrical => Topic started by: doeslayer on June 19, 2006, 12:54:58 PM
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No spark on my 81 TA that has the Pontiac 455 in it now and I'm not that mechanically inclined.Can somone tell me a few things to check myself.The car was running when parked then 3hrs later nothing.It did this same thing a couple of weeks ago but before I ever got around to check to see if I was getting a spark it cranked right up as if there was never anything wrong.One thing I have noticed is that you can turn the engine over even when you have the automatic turbo 400 shifted into any gear.
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I'm not sure about the 455...but on a 400...here's what to do. I assume it would be similar to the 455.
Measure the voltage at the battery terminal and tach terminal on the distributor (while the engine is cranking). If the measurement is higher than 7 volts, you're OK to that point. If you're lower than 7 volts, you have a bad lead in to the distributor, bad bulkhead connection, or bad ignition switch. And, I'd check the ignition switch first because that's a moving part.
Assuming you have enough current at the distributor:
Do you have electronic ignition or points? If you have electronic ignition, check the coil with an ohm meter per the service manual (it would be impossible to explain it here). If that's OK, try changing the module. Also, check the cap and the spring in the center as well at the rotor. Sometimes the screws for the rotors work themselves loose.
If you have points....hey that was a long time ago for me! But check the dwell and the condenser. Also, check the coil...but I've forgotten how to do that on the old style ignition.
Or, you could just do a tune up and change the coil, module and plugs. That may or may not solve your problem. If it doesn't, you need to measure voltages......either isolate the problem or do like most mechanics do....change parts until it works.
The any gear thing is a big problem. Someone must have bypassed the neutral start switch. That switch is located on the base of the steering column near the toe pan. Or, the switch might be bad, but usually if they're bad the car won't start.....it's a purple wire and gray wire...thick wires if I remember the colors correctly (and that's from a 1978). This switch also works your back up lights.....do your back up lights work? It's possible that they do because one connector fits into two blades of the neutral switch to run the neutral/park start function, and another connector fits into two blades on the switch to run the back up lights. So, it could be that the neutral start function was jumped and the back up light function is intact. Interesting problem. If you lived near me I'd love to solve it.
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Don't know what I did exactly to fix it it but I've got fire now. Had power at the terminals of the HEI coil so removed the MSD coil and elected to change the coil,cap and rotor.Still no fire so put my old parts back on and wiggled all the connections under the rotor and was going to try another distrubutor but it fired right up and has been doing so since but it's got me afraid to drive it far from home and I've since developed a bad oil leak that looks like it's coming from the rear main seal What can I expect to pay for a shop to replace the rear main?? It's looks like more than I can do myself.