Re: 3hp evinrude won't run unless chocked???
Sounds like fuel starvation to me. Your motor may or may not have a tank filter (actually a screen). I have a Johnson jw10 (1953) that doesn't but had two later versions that did and the screens came out by unscrewing the external tank fitting. Except for cowl these are the same as Evinrude 3s. There's not much mystery on these simple engines and carbs. 3/8 out might be a tad lean for the high speed needle. I would back it out more...initial settings for it are 1/2 to 3/4 out...and the high speed needle has to be dialed in before doing the low speed (low speed settings start at 1 to 1-1/2 out).
Other situations that happen...needle valve sticking, float height wrong or the nozzle gasket leaking air. The carb bowl can be dropped off these without removing the carb so checking this stuff is fast and easy...but a few light raps on the carb with a mallet while the engine is running will sometimes release stuck floats and needle valves. There's a tiny pocket in the bowl at the tip of the high speed needle that gathers trash easily and blocks gas flow. I've "field" cleared this area by taking the needle out and letting fuel flow out a few minutes to purge it. Whatever the problem is I don't think it's major.
You did unscrew the tank vent and make sure it's clear, right?
