Ignition Problems

[Dustydog]

I have an 5.7 L GM i/o I’m not sure about exact year (late 80’s) with a thunderbolt ignition system. When holding wire from coil to distr. on ground to check for spark I get nothing. I am getting 14 volts to the positive terminal on the coil and even the negative terminal tests at volts. Any ideas? How can I check coil? I’ve read in the mercruiser manual that you need a special testing analyzer to check coils used with the thunderbolt ignition.

 

[boatingfool]

Re: Ignition Problems

If you have power coming into the coil but none coming out it sounds like a bad coil.

 

[stevied]

Re: Ignition Problems

on the thunderbolt V ignition systems, it may not be a bad coil but a bad distributor sensor. If you have a Merc. manual it has a flow chart in there for testing the ignition system. The distributor sensor is located under the distributor cap. It has two wires going to it(white/green white/red) Use the flow chart it will tell you where your problem lies.<br /> Good Luck