I have a Speed Density TPI and I am losing spark while the car is on. The tach will all of a sudden move up and down and the car will try and turn off. Usually if i give it gas i could keep it on but if it turns off it will take a while to restart. The car has a MSD ignition and a large cap HEI distributor. Please help.

 

if the tach is bouncing it's your pickup coil in the distributor.

 

what about the ignition module?

 

if the ignition module wen tout you would have a hard time starting the car when it was hot or it would just cut out completely. the pickup coil causes the tach to flutter. you car should have a small cap dist since it's tpi, did you swap in the hei or did the PO?

 

It was origanally a 86 block which used the large cap HEI. The whole distributor is less then a month old but it barely started doing this. It will take about 10 minutes to restart once it cuts off. What would cause either one to go out? which is more likely?

 

no hot start is definitely ICM go replace it and come back with an update.

 

sounds good. the tack doesnt like go crazy it just moves cause its losing spark I think.

 

Will the ICM cut off the injectors? cause when its not starting I have no injector pulse or spark!

 

I'm having kind of the same problem. I have pulse and spark, but its faint. My car will start just fine, but if i turn it off and try to restart, it will crank but not fire up, unless i wait 7 or more minutes.