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1998 115 HP Mercury

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supel1

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I have a 115 HP Mercury two stroke (1998 model). Lately when the motor is run for a period of time I seem to lose a cylinder. If I let the engine cool down for a period of time it will run fine. I do not think it is fuel related because it will run fine for quite a long time and then start to lose power.
I have replaced the spark plugs but this did not help. Any good ideas where to turn next?
 
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Re: 115 HP Mercury

Run it HARD until it drops the cylinder, then immediately switch her off and pull all the plugs. The one that's not running will reveal itself. If the wiring to and from the coil looks okay, replace the coil for that plug.

Jeff
 
Re: 115 HP Mercury

Yes - and if you can't find a bad coil then the trigger is another likely suspect.

Almost positive you have a cracked/broken winding (bobbin) on one of your components.

When it heats up, the copper expands and you lose continuity - when cold the wires are "squished" together so they conduct electricity.

You can test in the driveway with "muffs" - just hit the coils (in turn) with a blow dryer and heat them up good (and if the wife/girlfriend complains, just tell her you need her hairdryer for a scientific experiment that will save you hundreds in shop service costs) :)
 
Re: 115 HP Mercury

You're a clever fellow, Graham! I'd never get the olde girl to do that for me, however....

Jeff
 
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