Choke On, off or Auto 1968 40 hp - bogging

[Wayland85]

I have a 1968 40hp evinrude. Model # 40873. Should I keep the Choke on Auto went starting and running? It is a butterfly choke.

I do have a problem once the engine is warmed up, it runs for 2 to 3 minutes at full throttle then dies. It will instantly restart and you can go another few minutes at full throttle. It will stay running at idle. I have new gas and the tank was vented. No kinks and the fuel line is a couple years old. When I first get in the water it runs for 10-20 minutes then the 2-3 minute issue starts.

I run the engine with the Choke off.

Any thoughts?

 

[tx1961whaler]

Re: Choke On, off or Auto 1968 40 hp - bogging

On mine, I run it "OFF" (e.g. locked open) once it's started and running. No need for it after that. I have heard of the springs breaking on the choke and allowing the butterflies to flutter closed.
Your issue seems hard to pinpoint. If it were running out of gas, I would not think that it would instantly start back up. Almost sounds like the ignition switch is cutting it off. You can eliminate that by disconnecting the two black kill wires coming from under the magneto plate temporarily. You'd have to use the choke to kill it, so set it to "auto" in that case and use the electric choke.
Hopefully it is not overheating. You should be able to put your fingers on the head without burning them. The little infrared temp guns are better....