Evinrude Fastwin 18 Bogging at high speed

[Michael Wyse]

Up until today, my 18 Fastwin ran perfect, when I would try putting the throttle wide open, it would try to go up in the rpm’s, but then bog down as if I was just moving fast enough to make a wake. I’ve seen that the coils have possibly caused this issue, But two years ago I replaced everything on the magneto, and it has brand new plugs. I took them out for inspection, I could tell it was lean on gas, and two years ago I put all new fuel lines in so no air leaks into them, and I don’t have the problem of that happening anymore. I have a 1964 Model, Evinrude took out the high speed needle that year, so I cannot control the high speed, thanks for the help!

[seakaye12]

I would check to see if you are loosing spark on one cylinder.  Check with an in-line spark checker.  Or;  after it runs bogged as you describe….take a digital thermometer and check cylinder head temps top and bottom.

 

 

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Michael Wyse

[labrador-guy]

?

[fleetwin]

Well, you have to determine whether you have a fuel or an ignition issue.  I’m guessing igntion…   I would invest a few of those inline neon spark testers.  Lash the boat tightly to the dock when the sun is almost down.  Now run the engine with two testers inline to see if you are dropping a cylinder…

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Michael Wyse

[olcah]

I recently had a somewhat similar problem with my Evinrude 18 HP.   At speed the motor would run and then stop.  It would restart and then do the same thing again.   It would run continuously only at low speed.   Although I had tried to flush the fuel filter element with carb cleaner, the filter was partially plugged.  Easy test is to remove the filter element and run without it.

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Michael Wyse

[crosbyman]

well if not electrical…. hand pump up the fuel in case  the pump can’t keep up.

 

you did….   clean the carb HS jet  #76                       and  post #56  ???                       fat donut #57  in place… open the tank vent

Evinrude Carburetor Group Parts for 1964 18hp 18402 Outboard Motor (marineengine.com)

Joining AOMCI has priviledges 🙂

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Michael Wyse

[Steve D]

Not sure if your bogging is like what’s in this video, but I showed it a few years back and a couple experts immediately said ignition. I replaced the condensers, wires, and one coil and it ran great after that. I know you said you replaced everything on the magneto, did that include wires? Or at least check the connection at the coils and and the boot. This one looked like it was arcing from a bad/corroded connection at the coil.

https://flic.kr/p/JZWgQ8

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Michael Wyse, The Boat House

[Author]

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