1981 Johnson 75hp outboard rough idle/misfire on accel/decel J75TRLC1M

[Dsmmilw]

Pretty much as the title states, but here are the details..
Last year after tubing, I had to switch tanks is when it started. I replaced the plugs and wires on the lake, no change. Would not idle, shook terribly when the fast idle lever was used. I have since removed the carbs, and have completely and thoroughly cleaned them, performed a compression test, 120# on all cylinders, along with replaced 1 defective ignition coil. Still experiencing the same symptoms.. I'm starting to develop a raw spot on my head from all the scratching, and am now turning to you guys for some help.
Any advice on where else to look would be greatly appreciated!

 

[Daviet]

Re: 1981 Johnson 75hp outboard rough idle/misfire on accel/decel J75TRLC1M

Use an inductive timing light and check each plug wire when the engine is acting up and see if all cylinders are firing. If the ignition system checks out, try squirting some fuel mixture into each carb and see if it picks up and runs properly. These checks should determine if you have a fuel or ignition problem.

 

[tumblweed9999]

Re: 1981 Johnson 75hp outboard rough idle/misfire on accel/decel J75TRLC1M

I had a Evinrude 3 cyl do that to me. Turned out to be the power pak. tossed one in and she was fine.

 

[emdsapmgr]

Re: 1981 Johnson 75hp outboard rough idle/misfire on accel/decel J75TRLC1M

Any chance your fuel tank has a little water in it? Also, possible it is out of time on one cyl. Are you sure you have the correct coil wire on the right spark plug? The power pack wires should be color-coded to each coil.

 

[boobie]

Re: 1981 Johnson 75hp outboard rough idle/misfire on accel/decel J75TRLC1M

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