85 evinrude 90HP

Boat ran fine until this year. Started having problems after first trip out. It will run fine on land, but when I put it on the water it doesn’t want to run. It won’t start without choke when it’s in the water and then it runs for a few seconds then makes a hard THUNK sound. It’ll do that a few times then eventually choke out and die. Won’t even try to start without choke. Pulled it out of the water, and it runs just fine in the parking lot. No problems there. Any ideas?? I’m stumped. I’m also not very mechanically inclined… so.. hoping somebody will have some insight for me.

Thanks


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What year model is it?

1985 evinrude 90HP v4 2-stroke


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I am thinking dirty carburetors. Have heard of coil packs being bad as well

I would check the carbs first. Dirty and May need a rebuild. Check your fuel lines as weel to ensure they aren’t leaking.

Sounds like main jets are plugging up. Best indicator is running on shore but not with back pressure on exhaust after put in water. Just to start might try spraying some good carb cleaner in throat of carbs. Let it sit 15-20 minutes then do it again. Do this several times. Then give gas tank a good dose of sea foam and hook to hose and just let it run for awhile. Make sure if using muffs that you keep a close eye on them so you don’t loose water pressure.

Did that to my 2000 Johnson 150 after it had sat for 6 years. Seafoam helped it out alot. I ran it in a stock tank so I had plenty of water

Quote:

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Originally Posted by Cray

Sounds like main jets are plugging up. Best indicator is running on shore but not with back pressure on exhaust after put in water. Just to start might try spraying some good carb cleaner in throat of carbs. Let it sit 15-20 minutes then do it again. Do this several times. Then give gas tank a good dose of sea foam and hook to hose and just let it run for awhile. Make sure if using muffs that you keep a close eye on them so you don’t loose water pressure.

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Thank you. I will try that


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I'm a believer in Seafoam in every tank.

It is good stuff. I certainly like it in 2 strokes.