No Spark

Been having trouble with intermittant "no spark". Truck will start fine when cold but will not fire after short intermission in trip. For example: Leave work and go to store-come back out and it won't fire.

I've replaced coil, pick-up coil, electronic module. Still no help. This is wierd but I have a spark tester and if I pull a plug wire off and connect it to the spark checker (which is clipped to ground) it will fire immediately. This has been working for awile but lately nothing helps. Any ideas would be greatly appreciated.

Thanks alot!

When the vehicle does not start, check the ECM fuses A and B. Do you have power at these fuses? If not check the connections at the firewall behind the battery. There is a block where all the wires go thru. Pull it off and check all the connections. Make sure none of them are broken/corroded. Repair as necessary and apply grease and reinstall. Good Luck.

Is this Electronic Control Module? Are these fuses in the fuse block under the dash? The vehicle I refer to is a 1985 GMC K1500 truck. I have removed the stock distributor and replaced with an Accel HEI. My battery is in the front passenger side. Is the block you refer to on the firewall? Sorry to be so dense. I'm just a shade tree mechanic.

Thanks again for the help!

Sorry, is that a carburated vehicle?

Yes carburated. Edelbrock performer. The only thing going to the distributor is the power wire. It has had power to the distribitor when it wouldn't spark.

Looks like you may have a bad pickup or module.

It kinda sounds like the module to me too, but since you've replaced it already (and what are the chances of a new one being bad just like the one you are replacing? THAT could only happen to ME! :eek: ), maybe the problem lies elsewhere. I'd take a close look at the 12 Volts being supplied to the coil, with special scrutiny applied to the wire's integrity and the connections!

Hope this helps...

-Andrew-

edited (because I never get it right the first time): be sure the coil is properly grounded. You can send 12 volts or 12,000 volts to it, and if the ground is not good, it won't do a danged thing!

OK will check the ground to coil.

Thanks again!