tough one(long post)

[spademan87]

I have a 89 s10 blazer 4.3 4wd and it keeps frying the ignition module and the ignition coil. no one seems to be able to tell me why or what the problem could be but it started off with the truck cutting off when i would slow down to park then one day it did it at advance auto so i put a distributor cap, button, and coil on it and it didnt help it just kept running like crap and cutting off. then i put the ignition module in and a fuel filter and then it wouldnt start at all. got it towed to a shop and they said fuel system is fine(including pump and injectors)they put in a new distributer and module which fryed when they started it so they told me that the coil and module needed to be replaced at the same so we did and it started and ran fine for about 20 miles then shut off again and wont start got it towed back and they told me that the module and the coil fried again and they have checked all the wiring over and over if i were to put another coil and module on it it will start but wont last long other than that all of the routine stuff is kept up and the truck has LOTS of new parts so if any one has suggestions im open and would greatly appreciate it

[mike2004tct]

When was the last time the plug wires were changed.

I had a similar problem, don't remember the trouble code, but it was "High Voltage Spikes", which fried the ignition module. Even took out the EEM computer.
Replaced the plug wires, and everything has been fine for the past 11 months.

[ken_man_1]

Have you checked the voltage output from the alternator/battery? It's extremely rare that the alternator will overvoltage, but I've seen it. I would hope a shop would check this already tho.