1993 Mariner 2 Stroke 25hp Shorting to ground and no high speed throttle.

[clc48301]

I'm having trouble with my 93 Mariner 2 stroke 25hp EL outboard. Normally the boat tops out at 20-22 mph, but it lost all high speed throttle and wouldn't go over 6mph. When I removed the cover I felt a slight shock. Turns out a mouse has chewed some wires. Also you can hear popping on the radio when the engine is running but it goes away when the engine is off. So there is definitely some transients gremlins in my power lines. I replaced all the wires with chew marks that I could find, but the motor still runs poorly and still have a short. I'm thinking that its either the ignition coils or stator. I pulled the cover and looked at the ignition coils and don't see any cracking. I want to check the stator but I cant get the flywheel off to save my life. I stretched the teeth on my gear puller! I think its the ignition coils are bad because when the engine is hot its harder to start, and stalls out in neutral, but if i dump it into gear it will run. The longer the engine runs at full speed it slows down from 6mph to 4.5mph.

Does anyone have ideas?

 

[SteveVT]

First of all, check if both cylinders are firing, by pulling off one spark plug wire at a time, using an insulated puller. If the engine doesn't slow down when one wire is pulled, that cylinder isn't firing. Check the spark plug, the wire, the coil connections, including ground, for that one cylinder. If they are all okay, remove the coil for that cylinder and trade it with the coil for the good cylinder. If now the bad cylinder fires, and the good cylinder has stopped firing, order a new coil.

If both cylinders are firing, check that all throttle linkages, cam, etc are connected and working. If they are, clean/rebuild the carburetor. Don't mount it back on the engine yet.

Check gas lines, filter, and tank for deterioration/debris. Fuel lines can look good on the outside, yet crumble on the inside. Replace whatever is necessary.

Only then, bolt carb back on the engine. If debris clogged the carb, then it came from somewhere else, and the problem will return if you don't locate that source and eliminate it.

 

[clc48301]

Thanks Steve, I put new plugs, wires, ignition coils and carb kit, motor runs better than it did before

 

[flyingscott]

Disconnect the tiller kill switch and run it. What is the compression? Does spark jump a 7/16" gap?

 

[clc48301]

The water exit line and the spark plug wire were rubbing and eventually shorted to the cover. I think this short killed the ignition coil. once I replaced the coils and wires and made sure they didnt touch it works fine.