Originally Posted by
JohnF
If the float was stuck closed then it wouldn't run at all. Yours is running at low idle.
If the float didn't open enough to allow a fuel rate enough for high idle then it would probably reach high idle and then surge. Unless it was really bad, then it would die.
The float level affects the "accelerator pump" function of the carburetor. This functions is accomplished via an immersion tube (huh, the parts blowup in the manual above calls it an Emarsion Tube???) that sits in a reservoir. When call for, the fuel is sucked out of this reservoir. As the level drops it un-ports air holes in the tube effectively increasing air. What is trying to happen here is when you open the throttle the air flow can accelerate faster than the fuel which is heavier so the carb meters a bunch more fuel at this change over. The important part (sigh) is that the reservoir level is the same as the float level. If the level is too low, then the air/fuel gets too lean and the engine dies. If this is the case, you should be able to creep slowly to high idle.
As a side note, the main jet is in the bottom of the float bowl. If the float is set too low the engine will run fine on the level but die when the jet un-ports. Probably pointed downhill or port side high. That's really a function of the float bowl geometry in the design but a too low float adjustment screws that up.
I'm still thinking bypass holes are plugged. Second guess is fuel pump or float valve not allowing enough fuel flow through.
And for draining I usually unplug the fuel pump and let the engine run it mostly dry.