Strange hesitation problem, any suggestions??

[2Slow]

I have a strange hesitation problem. My 21' Eliminator has a 1990 454 Magnum w/carb, runs amazing 81 MPH on GPS. But, after driving for a while then driving in a "no-wake" zone, it starts to cough, sputter, somtimes back fire, and stalls. I've visually checked everthing and nothing looks out of
wack, and the parts cant be checked (by my mechanic) becasue they work most of the time. It has the factory
Thurderbolt IV ignition. When it stalled last time, we took the coil wire off and put a skrewdriver between the coil wire and the distributor cap, no spark, waited about 20 minutes, ran fine again?

Also if a coil was messed up, what would be the symptoms??

Thanks for any help.

[Techno]

Coils are oil filled transformers. If it goes bad sometimes the oil can slosh to one side and cause this works don't work problem. The oil is the insulation for the 50,000 volt windings. I had a car that would die when you turned right but not left, the coil was mounted horizontaly. New coil and no problem.

I think you pegged it. A 10 year old coil is a good culprit. Your lucky, coils are cheap and easy to change.

[DaveR]

Be sure and post this on the Scream and Fly Offshore tech board also.

[ODDD1]

2slow...if you are losing spark when hot/idling you may have a bad sensor in the distributor...easy way to troubleshoot this next time it fails......make sure you got 12v at the positive side of the coil with the key on...then look at the back side of the distributor, you will find 2 wires, a white/red stripe and a white/green stripe....take off the wht/grn and touch it to a ground,any ground...every time it touches you should get a spark out of the tower on the coil....this tells you the switchbox and coil are ok...

[seacow]

another thing is if the exhaust temps are getting too high, which would be greater at idle, the ign. module on the port exhaust elbo can get too hot and short internally. one way to tell would be move module to back of intake temp. and run again with engine cover down to raise heat levels