1960s 3 hp evinrude yachtwin probem

[1957evinrude]

I solved the heating problem but now another problem. I checked compression on this engine and it has 70/71 not great but I think okay. It idles really well in the tank but when I put it about half throttle it quits but If I spray gas/oil mix in carb it continues to run as long as I continue to spray oil/gas mix. I took another carn off my ducktwin to see and still does the same thing.
Im thinking possibly air intering from somewhere?? I looked at the reeds and they seem fine. Whats the next step? Replace all the gaskets from the carb to the reeds ??
I tested the tank and I have steady fuel flow and clean tank I also have an inline fuel filter. Any suggestions would be appreciated.

[wiscoboater]

Did you try re baselining the needles and running it again? I would try that before anything else. I believe lower needle 3/4 turn out, upper 1 1/2 from seated. But I sometimes get that mixed up. If I did, someone will correct me soon here.

[chris-p]

Is the float catching on something? Needle sticking? Have you already cleaned/rebuilt the carb?

[1957evinrude]

Oh this one has a fixed high speed jet. I tried with a good carb off my ducktwin and it still does the same. I just ran the ducktwin and it runs good then I took carb off and put on the yachtwin but still runs the same I also swtirched tanks. For some reason it seems to not be sucking the gas. Air leaking in from somewhere ??

[1957evinrude]

Yes Chris I had already took care of the carb . I took it down twice to be sure . Maybe the gaskets need to be replaced for the intake?

[chris-p]

I do not do a whole lot of these 3hps, but I really doubt it. Maybe i’m wrong.

I have a 3hp as well that will not pull fuel. I found the exhaust FULL of carbon, completely blocked, so had thought for sure I found my issue, but still had the same trouble after cleaning it all out. Might want to check under your exhaust plate as well.

Keep us updated on what you find though.

[wedgie]

The throttle shaft might be worn allowing air in. Is there a lot of slop in it? Wait ’till Mumbles checks in, he’ll elaborate further :ugeek:

[1957evinrude]

I tried another good carb and still the same so I don’t think its the carb. I ran my other 3 hp with the other carb and ran good then I swapped carbs and still the same.

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 6 years, 6 months ago by Tubs.
• This reply was modified 4 years, 2 months ago by Tubs.

[lindy46]

Are you using the built-in gas tank or an external tank?

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