Mariner coil

[sander]

Is there an easy way to check the condition of a coil or spark plug wire?

My engine is a 1990 15 HP Mariner. (Merc?) It ran fine and suddenly, in mid trip, began to stutter and stall in lower rpms. Changed plugs twice but to no avail. There is spark at the cap, and it runs on one cyl. , if I keep choking it. Surprisingly , I got it to plane just fine on the way home, and the 'faulty' cyl. even burnt the plug nice and clean. At low rpms, that plug was wet and oily . (two stroke).

Compression is good on both cyls. Is there an easy way to check if coil or plug wire is at fault?

Thanks guys.

 

[guyjg]

There is spark at the cap, and it runs on one cyl. , if I keep choking it. Surprisingly , I got it to plane just fine on the way home, and the 'faulty' cyl. even burnt the plug nice and clean.

It sounds more like a carburetion issue. Put a timing light on each plug wire at the plug.

 

[fastjeff]

Plugs ALWAYS run dark and wet in low speed only operation. A plug hot enough to avoid that would melt the block at full throttle!

Agreed with guyjg: it sounds like a carb issue.


Jeff