115 evinrude not firing on one spark plug

Patrick O.

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I have an 80's model 115 Evinrude, and I was going to sell it yesterday when the guy I was going to sell it to noticed it wasn't firing on one of the spark plugs. The compression was around 110 on all cylinders though, which I know has nothing to do with it just thought I'd throw that in there. Anyway he said it may be something to do with the coil or coil pack???? Is this where I should start trying to diagnose the problem? Also one of the wires on the coil pack has electrical taped wrapped around it. Any help with this would be greatly appreciated :)
 

boobie

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Re: 115 evinrude not firing on one spark plug

Start it up and pull one plug wire at a time with an insulated pliers to narrow it down to a cyl that isn't firing. When you find the bad cyl, switch coils with one that is firing and if the prob goes with the coil, you have a bad coil. If not maybe a bad power pack.
 

Patrick O.

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Re: 115 evinrude not firing on one spark plug

But how will I know which one isn't firing if I can't see the other end of the spark plug? And I doubt this is what you mean but we had all of the spark plugs out of it last night and it's the top left plug that isn't getting fire. We never had it started though. Is it safe to start with on missing like that?
 

Patrick O.

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Re: 115 evinrude not firing on one spark plug

Also I'm not sure if I should mak another thread or if you could answer this but what kind of hydraulic fluid should I put in my trim? or is there a grease I should put in it or what?
 

Daviet

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Re: 115 evinrude not firing on one spark plug

If you already know which cylinder isn't firing, swap the coil with one that is as boobie suggested. If the no spark moves with the coil you have found your problem, bad coil.
 

boobie

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Re: 115 evinrude not firing on one spark plug

You can use ATF Dextron 2 or power t/t fluid.
 

busted-bayliner

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Re: 115 evinrude not firing on one spark plug

But how will I know which one isn't firing if I can't see the other end of the spark plug? And I doubt this is what you mean but we had all of the spark plugs out of it last night and it's the top left plug that isn't getting fire. We never had it started though. Is it safe to start with on missing like that?
do exactly what boobie says below
Start it up and pull one plug wire at a time with an insulated pliers to narrow it down to a cyl that isn't firing. When you find the bad cyl, switch coils with one that is firing and if the prob goes with the coil, you have a bad coil. If not maybe a bad power pack.
 

Patrick O.

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Re: 115 evinrude not firing on one spark plug

Will I be able to see the fire from the wire to the spark plug or will the engine just run differently? the one that isn't firing is the top left plug, that would still be the same cylinder or would it not fire on one plug and affect another cylinder?
 

Patrick O.

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Re: 115 evinrude not firing on one spark plug

ok so I just went to try to switch the coil to a different coil and it doesn't look possible to switch just one unless I splice the wires. Is that an ok thing to do or should I switch thyem both to the other side?
 

emdsapmgr

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Re: 115 evinrude not firing on one spark plug

If you pull one of the spark plug wires off (use some insulated pliers) the plug when the engine is running, the engine should drop rpm's-noticeably. If you pull one of the spark plug wires off and the rpm's don't drop-that plug is probably not firing. To swap the coil, you must pulsh the wire end and it's pin/tip out of the connector. Swapping them tests each coil. Another common failure item is the power pack. Many of the early 80's engines had dual power packs. Each controlled the spark to one head. You can also swap them-if the non-spark problem moves to the other head, then replace the bad pack. On rare occasion, the lower spark plug wires can misfire (go to ground) on the lower cowling latches. If you run the engine late at night (in the dark) , sometimes you can see the spark going to ground on one cyl.
 

seahorse5

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Re: 115 evinrude not firing on one spark plug

It may not be an ignition or a sparkplug problem. The carburetor low speed circuit could be plugged with debris or varnished fuel which would block any gasoline and oil from reaching that cylinder
 

boobie

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Re: 115 evinrude not firing on one spark plug

You still have to make sure you have spark to the cyl that is dead before digging into the carbs.
 
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