1977 Thunderbolt 6 -- Ignition Miss ??

[calboats]

The last outing the motor stopped in mid lake, just sputtered out from a 4000rpm cruise speed. Waited a few minutes while on electric troller motor, tried to start it, and starts right up, no problem. Ran strong all the rest of the day, but I'd like to be sure, as I will be on the Columbia river 200 miles away, soon, no room for oops!!

Plenty of fuel, good fuel pump, batteries good. Motor was dealer rebuilt and installed two years ago, and has run great since I got it.

My auto mech. says the coil might be getting hot, restarting as it cools. Buy a new coil, or test the one on motor. Boat guy says pull the dist. , flywheel etc., redo it all, at over $200. Seems a bit radical, but ??

Can a normal person rebuild a Thunderbolt ignition, points and condenser like my Triumph spitfire?? Or is this a service only thing due to marine equip. differences?? I do have a Hayes manuel, but pix are sketchy on this.

Thanks, Cal

 

[Moody Blue]

Re: 1977 Thunderbolt 6 -- Ignition Miss ??

Could be any number of things. Not a very good approach to just start replacing parts that "might" be bad. That can get expensive very quick and you may still not solve the actual problem.

Water pump, when was the last time the impeller was changed? Possible it overheated? I once picked up a plastic bag on the lower unit while running. Overheated quickly but I caught it in time to prevent damage.

Could it have been a little water in the fuel and once it was consumed, problem solved?

That motor does not have points or condensers. It uses a "switchbox", a black box of electronics. Ignition parts are expensive so test before replacing. Coil failure is rare but not unheard of. Remove and inspect the dist cap for cracks or signs of arcing. Check the condition of the center carbon electrode. Inspect the plug wires for signs of failure (cracking, breaks etc). Check all the internal wiring harness for signs of corrosion or failing insulation. Could be an intermittent short or open circuit. Those old wires are notorious for the insulation crumbling off.

There are tests for the ignition electronics posted under the FAQ section, BUT if it is a random intermittent problem, the only way you are likely to find it is once the motor quits.

Hope I've given you something to go on to get started.

 

[calboats]

Moody Blue--Thank You !! Re: 1977 Thunderbolt 6 -- Ignition Miss ??

Moody Blue--Thank You !! Re: 1977 Thunderbolt 6 -- Ignition Miss ??

Great advice, thanks much. I pulled the coil, and it had both water and oil (condensation?) all over the enclosed coil body. I just put on a fuel line cannister water catcher, and new fuel lines from the tank, a good idea anyhow. Now to the lake to water test the boat again.

Just as an aside, my marine place said the coils rarely packed in, as you said -- but got me a new one out of stock for $20. so I replaced the other one anyhow. They also confirmed that as I have no points, I should be good to go now. Called Mallory, and that "single coil" type is not available any more.

Guess I should be looking at more power boat oriented web sites, the local "coots" have good events locally, but I'm kinda an outcast with a motor over 10 hp. There must be an Oregon base power cruisers club out there.

Thanks Again, Cal Drake