Spark plug not firing after engine is warm

[bonitoman]

My 95 6 cyl 150 intruder will run for an hour and then when I check the #4 plug it does not fire. I bought a new dual coil thinking that was the problem and the same results. After a while the same plug that was firing is not firing. Great compression and getting fuel.

 

[tashasdaddy]

Re: Spark plug not firing after engine is warm

how are you checking spark? have you tried a new plug? have you swapped a known working coil with the suspect coil?

 

[jonesg]

Re: Spark plug not firing after engine is warm

you replaced the dual coil and its still a problem?

try swapping the trigger wire from the powerpack (plugs out) when the problem starts, see if the problem follows the wiring.
On my 1994 150 the wires "just" reach (the small primary wire) to the coil.

I'd say power pack but it could be poor ground on the coil or ...
plug wires if you haven't try swapping them around (mark the bad one first).

I got a power pack for mine, around $140-150, fixed it .

 

[Bob_VT]

Re: Spark plug not firing after engine is warm

Did the coil come with a new wire? When things warm up electrical "cracks" or "Breaks" show up. What is the next closest thing to that coil? You could be getting sparks leaking across from another coil too.

 

[jonesg]

Re: Spark plug not firing after engine is warm

My 95 6 cyl 150 intruder will run for an hour and then when I check the #4 plug it does not fire. I bought a new dual coil thinking that was the problem and the same results. After a while the same plug that was firing is not firing. Great compression and getting fuel.

I think you can try emulating the problem by heating the PP with a hair dryer, if it starts acting up when heated its probably the problem.
Heat the PP with the engine cold and spark test it.