Yamaha 2 stroke (6hp) Only powers up when I cut off fuel supply.

[davidturnswood]

Howdy,

I purchased an older Yamaha 6 horse, 2 stroke outboard that starts, idles, runs, but won't rev up to full power unless I kink the fuel hose or disconnect fuel. If I do this it runs great and my 10' Achilles gets up on plane no problem. However, that is short lived, as after 15 or so seconds the engine is starved of fuel and shuts down.

Could this be a float issue? I have a feeling it's possibly sending too much fuel as I try to rev up, and only firing on one of two cylinders. I can't understand why else restricting the fuel would cause it to operate properly.

Any suggestions would be appreciated. I took the carb apart and cleaned it out some, but did not soak overnight.

Thanks!

David

 

[racerone]

Inspect float valve and fuel pump diaphragm.-----Motor is getting too much fuel and running rich.----Fuel is not burning properly , thus the lack of power.

 

[davidturnswood]

Pump diaphragm looks good (not ruptured at least). Carb is still clean. (Cleaned it recently). I don't know what is normal for the float. The pointy rubber bit seems good. Not sure what angle the tab should be adjusted to. The little brass tab coming out of the float is not perpendicular to it, but bent up slightly (bent toward the bottom of the bowl). If I hold the float upside down it rests not horizontally, but slightly dipped into the aluminum housing.

 

[davidturnswood]

I just bent the brass tab a bit to make it more likely for the pointy rubber valve to close.. Going to test it out and report back.

 

[QBhoy]

Best of luck. Not much usually bothers these incredible engines, other than bad fuel...a carb clean or embarrassingly...forgetting to open the vent on the fuel tank ! Haha.

 

[raczekp1]

you bent in wrong way this brass in float body

 

[johnson89]

Did anyone hear what was done to fix this motor, I have a 1993 6hp Yamaha and doing the same thing, I ordered a carburator rebuild kit for it but this motor is very clean and everything looks good, float, seals if you turn the carb over, fuel pump looks good, no tears, very clean , I started a separate post but haven't had any help .

 

[ct1762@gmail.com]

well that was certainly your issue! You really need the factory manual to see what the float drop settings are supposed to be though. i'm guessing 28-35mm drop or so to get that needle open.