I have a 1987 Classic Fifty 45hp with a strange problem. It is hard starting initially and will only run on 3 of the 4 cylinders. After it gets warmed up, shut it off and let it sit for 15 minutes and it will run as if it never happened. Also, if you don't wait the 15 minutes, after a spell, the 4th cylinder will sometimes start trying to kick in and will eventually run normally for the rest of the day as long as you don't let it get stone cold after a couple hours of fishing.
Now it has changed symptoms somewhat which caused me to change the switch box which physically looked faulty, such as leakage of the potting material. I still have to do the warm up/shut off procedure that works sometimes, but now there is an erratic miss or intermittent dropping of the affected cylinder all the time now after I get it to finally fire.
Do coils sometimes start to work after they get warm or perhaps the warmed cylinders just combust fuel better when a weak spark is the possible culprit causing it to suddenly be enough spark to fire it?
Sometimes, if I rev the engine in neutral, it will clear the cylinder and start running on all four, sometimes not. On a motor that is over 20 years old, is it a good idea just to change the coils out anyway? It's also been gradually getting harder to start, even when warm so the condition seems to be getting gradually worse.
The miss is an on/off miss, such as there would be if there was a bad wire or loose connection somewhere but I have checked every inch of the harness and that would not explain it curing itself in exactly the same way for so long, I wouldn't think.
Can carbs cause abrupt on/off missing like that
Now it has changed symptoms somewhat which caused me to change the switch box which physically looked faulty, such as leakage of the potting material. I still have to do the warm up/shut off procedure that works sometimes, but now there is an erratic miss or intermittent dropping of the affected cylinder all the time now after I get it to finally fire.
Do coils sometimes start to work after they get warm or perhaps the warmed cylinders just combust fuel better when a weak spark is the possible culprit causing it to suddenly be enough spark to fire it?
Sometimes, if I rev the engine in neutral, it will clear the cylinder and start running on all four, sometimes not. On a motor that is over 20 years old, is it a good idea just to change the coils out anyway? It's also been gradually getting harder to start, even when warm so the condition seems to be getting gradually worse.
The miss is an on/off miss, such as there would be if there was a bad wire or loose connection somewhere but I have checked every inch of the harness and that would not explain it curing itself in exactly the same way for so long, I wouldn't think.
Can carbs cause abrupt on/off missing like that