Installing Thundebolt IV Module

I have been chasing an intermittent engine ignition problem in a 1986 5.7 Mercruiser engine with a Thunderbolt IV control module. I have already replaced most of the common tune-up components and am down to either faulty tach, alternator or ignition module. I?m going to purchase a new ignition module online so I have it with me when I go back to the boat for further testing. If I get to that point is there anything I should know about installing a new module? Is there a heat sinking compound needed to mount it to the flange on the riser?

Re: Installing Thundebolt IV Module

Sounds to me like all you're doing is throwing parts at it in hopes of finding the problem.
Here's the troubleshooting chart for your Thunderbolt IV ignition. When you have this undefined "intermittent engine ignition problem " follow the troubleshooting chart and see if you determine the problem.



Here's also a link so you can download the OEM service manual for your engine.
http://www-alt.mercurymarine.com/mnetdata/SERVICE/CRUISER/Servmanl/09/cover.pdf

Re: Installing Thundebolt IV Module

Don't lose the spacers where it mounts. Make sure you get the same one it will change your total timing if it is different.

Re: Installing Thundebolt IV Module

Don,
Thanks for the advice and manual link. I have a more detailed description of the problem but the chart doesn't help as all tests pass. Issue occurs first at higher RPM with a miss or stutter which can be worsened by operating other high amp accessories like trim. Problem continues to worsen with time (heat?) and stutter turns into stall. Engine will restart but each time stutter and stall reoccurs at lower and lower rpms until I cannot even idle for more then 30 seconds at a time. My mechanic's are pointing to shorting tach gauge, ac spiking alternator or control module failing when getting hot.

It just doen't appear in the catalog like the module comes already mounted on a flange so I was wondering if there was a heat sinking compound used or am I looking at the wrong one and the one I need should already be mounted to a metal plate?