I have 85 Mistress, always fighting real stupid issues...this weekend it was ignition...

boat ran fine all season so far, today the tach was bouncing all over and engine was losing power and cutting out....

has thunderbolt IV, I have spare parts, swapped boxes and pick ups, even coils, no change .....

then I just turned key to on position, the tach was bouncing... shouldn't do that!! then I heard a ticking from distributor .... like a light sparking.... so I unplugged ign box, still did it..... unplugged box AND the P/U coil... still did it with nothing but power to coil from key.....

SO..... sound like a grounding issue? either that or wtf would give it a touch of power out of nowhere??? then running boat back it cleared up and been fine..... I hate this type of issue....

Any ideas???

Check all grounds. Make sure battery terminals are clean and tight.Check for moisture under cap. Disconnect tach and try. A bad tach can take out an ignition system

Did all but the tach disconnect... I have had off and on issues with this engine and ignition over the last 4 years, 2 different tachs but who knows...

if you or someone you know has a run box un plug your main harness plug going to the engine eliminating the boat and all its wiring. plug the run box into your engine and run the boat. if the problem goes away the problem is in the wiring in the boat .if you still have the problem then its in the wiring on your engine. might have a bad connection on your engines wiring harness somewhere

Yea, I was thinking engine harness also, problem was intermittent with the Baja too, same harness on engine and same ing parts.... its so weird though, soon as I start to mess with it, clears up, then I say F it and run the boat lol

I may just go buy all MSD and rewire all by itself and call it a day, just wondering wtf would cause the coil to trigger with nothing connected to it...besides power..