18 h.p. Evinrude (18903D-E02708) 1969

by Richard
(Milford, Mi.)

Following a complete tune up I barrel tested my motor. starting & running was flawless. Headed to the lake fired it up and dialed in the rich/lean. Started out slowly increasing the speed. I could tell it was rich and it burned off shortly and ran smoother. Got the boat on plane and ran perfect. kept it there for several minutes as I went around the lake. Finally I pinned it, and it ran perfect for about 30 seconds and fell on its face. I dumped the throttle and it caught and stayed at idle. I repeated several times & no change. I checked everything I was told to do with no success. Check the following...fuel can & lines...good pressure...new fuel pump...coils...points & condenser...carb rebuild & float check...The engine seems like it's always rich. Had a couple other carbs that fit. No change. the high speed nozzle seems really huge, but I'm assuming that's the way it's suppose to be. Sincerely stumped!

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Dec 26, 2020
Falling on it’s face at WOT
by: Dennis

Hi, seems to me that you need to adjust your lean rich mixture at WOT. if you can run the engine at WOT for 30 seconds and then it falls on its face I would almost think it could be a runaway cut off switch. If your motor has one disconnect it and try it again and see if it falls on its face. I seriously doubt it would be points plug or a condenser or even the coils. If anything maybe a coil but I wouldn’t go there first. It is possible it may be starving for fuel when you go WOT but I would only consider that if you had a mechanical vacuum fuel pump. Good luck

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