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Help Please!!! 115 evinrude misfire

J

Joneswh56

New member
Help please ! My 97 evinrude misfires ONLY when engine is warm. Will not misfire when cool. Carbs are rebuilt new wires ,new power pack, new coils . Stator voltage is steady 310volts even when misfiring. Please. Any help is appreciated!
 
Inspect the stator under the flywheel closely. If it is dripping a sticky looking substance down upon the powerhead area, that would result in a AC voltage drop to the powerpack which would cause erratic ignition.

If the stator is okay, temporarily disconnect the black/yellow wire (kill circuit) from the ignition switch or the powerpack, which ever is easier. If this wire disconnect cures the problem, replace the ignition switch.

Let us know what you find.
 
I took flywheel off and removed stator. Everything looked good nothing melted. I will try disconnecting the switch wire tomorrow and see if it helps. Is there anything else I can check if that not the problem?
 
I took the boat out tonight. I disconnected the black/ yellow wire that controls engine shut off and the engine misfired still , so that's not the problem. Here is something interesting I found. Since it was dark I connected my inline spark tester to all the coils and found #3 cylinder is the one and the ONLY one that is dropping spark causing the misfire. I swapped coils with that cylinder and the miss stayed there. I also put my old power pack back on the engine and still #3 misfires Any thoughts on what could be wrong now ?
 
You may simply have a bad connector/wire that acts up due to thermal expansion when engine is getting hot. Pull all connectors, carefully 'pull' the wires and see if it stretches out indicating an internal broken lead. Most likely in the contact into the powerpack. When swapping coils, did you swap plug leads as well?
 
I'm assuming you mean the orange wires that connect to the coil from the power pack. It should have eliminated that being a problem when I changed the power pack because those wires come straight from power pack.
 
You have the leads from optical sensor and stator going INTO the powerpack, The orange to coils are going OUT of the powerpack. It might even be an optical sensor problem. However what I see from your post in IBoats, your #4 cylinder seems rather low in compression (94). Have you tested loss of spark by using a timing light or just hooking up a spark tester when problem occurs?
 
On this system, the best test tool is the 'ignition analyzer' sold as special tools.
However by experience on this engine, always keep an optical eye as 'spare'. If ignition problem, start by switching it. Cost far less than the instrument, and will sooner or later be needed!!
If you got a friend in the 'house alarm business' he might lend you an IR tester to check it out.
 
This may seem a little too simple, but have you tried swapping the spark plugs in the number three with another cylinder and seeing if the misfire moves?.
I have seen sparkplugs cause misses under all sorts of different conditions, it seem normal under test conditions, but when put under heat, pressure and into use it may be the cause of the problem. Just a thought...
 
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