Ignition Module - troubleshooting procedure???

I just bought a 1990 Mirage 211 Bowrider with a 350 alpha 1 and the dealer claims it needs a new ignition module (about $275) to cure a miss. The boat starts and runs and will plane (barely) but it has a persistent mild miss.

Does this sound like symptoms of a bad ignition module? I don't mind putting the money into it but I don't want to do it if its not the actual problem. How can I troubleshoot the module? What exactly does it do anyway and how often do they fail?

Re: Ignition Module - troubleshooting procedure???

Do these things just 'go out'? The previous owner said that it worked fine at the end of last season - but we've all heard that one before...

Re: Ignition Module - troubleshooting procedure???

I don't know what ignition system you have, but on a Delco EST ignition there are a series of tests to rule out everything but the module. If the problem still is not found, it says the module only has two failure modes, no spark and no advance. They do just "go out", but usually it's pretty obvious (more than a miss) when they do.

That said, if I were you I would want it fixed or I would think about returning the boat for a refund. At the minimum I would have them agree that if I paid to replace the module and it did not solve the problem I would not be charged for the part or the labor in replacing it. By dealer do you mean used boat dealer or Merc. Service/Sales dealer?

Re: Ignition Module - troubleshooting procedure???

If the risers haven`t been changed out since new, I`d be suspect of a leaking riser causing the miss.check the plugs to see if any show signs of rust. 4,6,3,5,

Re: Ignition Module - troubleshooting procedure???

It's getting late in the year. Make sure they either fix it right or you return it before the season ends. Do not put yourself in the position of this getting "patched up" into the offseason as by the time you get to check anything out your option to return will no longer exist.

Re: Ignition Module - troubleshooting procedure???

You should have the Thunderbolt IV ignition on your engine, and yes the ign. mod. can cause a miss. Usually you will find the terminals black or white with corrosion. If they are shiny and the engine is missing, I would suspect something else first. If you have advance, then the module is probably not your problem. Try a wiggle test on the terminal while the engine is running.
Do things like a complete tuneup (That is just a yearly maintenance item). Parts like spark plugs, cap, rotor all can cause a miss. Also check the plug wires, worn bushings in the distributor can cause the problem, carb problems can cause it. A compression check should also be done. Low or no compression, leaky, or stuck valve always cause a miss.
Lots of things can cause a miss beside a faulty ignition module. Check everything else out before dumping a lot of money on a module. I know a lot of people that blame the expensive parts that can't be checked and replace it only to find it still has the problem. Make sure the common stuff isn't causing the miss before ordering a module.

Re: Ignition Module - troubleshooting procedure???

I had similar problem with my boat. Mine is a 1988 King cobra 350, which came with points, so I went and upgrated to solid state ignition module from Pertronix and I still had a intermitent miss. Ended up beeing a spark plug in #2 cylinder, even though plugs were replaced. I took a timing light and hooked it up to each plug wire as the boat was idling to see if I have spark going to each cylinder and I did. The timing light flashed on each wire, so I replaced the plugs and all is well. Good luck.:d

Re: Ignition Module - troubleshooting procedure???

Thanks for all the advice. Forcing the dealer to fix it is not an option as it was one of those 'as-is' deals (really good price.)

I agree that its likely something 'simple', not the module. Solid state electronics are reliable compared to plugs, wires, distributor, etc.

Once I get some time I'll take it out on the water and do the normal troubleshooting for a miss.