no spark condition

[verbious]

1987 Mercruiser 260, Thunderbolt IV. Boat was in bad shape, but is slowly coming back to life. Engine turns over, starter rebuilt, new battery, replaced carb, cleaned fuel system. Installed an HEI for testing purposes while boat is on the trailer in the driveway.

Performed ALL troubleshooting for Thunderbolt IV ignition and all answers pointed to a faulty ignition sensor. That was replaced and reassembled. Turned the key and OH YEAH!!!! we have a running engine.

During round two of testing/revival the engine just stopped. Dead. All signs point to an electrical malady.

We have been over the forums over and over with no real luck. We cannot get a spark to jump from the coil to ground when striking the green/white on ground. Bad Coil????? Often times when turning the key off a weak yellow/orange spark will jump across the spark plug we use as a test.

Thanks for the info!!!!!!

 

[jerryb1]

Re: no spark condition

I'm not sure if this is your problem or not, but probably worth checking. I just had a problem with the Thunderbolt IV. Make sure there is a ground to the assembly. Mine is tied to the distributor. If you only have four wires going to the ignition amplifier, then the ground is made through one of the screws that hold it down. The igniton amplifier can't pull the coil to ground if there is no ground connection.