Logo
FULL SITE MENU

M30A strange idle problem

F

fvee91

Member
Hi All
I have a 2006 M30A (Carb pre mix 2 stroke). Owned since new, great little engine. The problem is, if I run the engine flat out for a length of time (10mins) then back it of to an idle, it will stall. If I throttle down slowly and spend a minute or two at 1/4 throttle then back off, she will idle till the cows come home.

Also when I flushed her out last night, I noticed steam coming out of the hole at the base of the power head along with water. The water flow was steady, and the tell tale was quite a strong flow. Is the steam a sign of trouble?

Thanks
Daniel
 
You would not have purchased that model (probably M30A4) in North America in that vintage. But...

Could be almost anything, most likely a fuel delivery issue. Probably a bit lean. What color are the plugs when the motor stalls? Could be almost anything in the fuel system, from a restriction in the strainer in the tank, to a pinhole air leak in the fuel line to the motor, to a weak fuel pump, incorrect float setting, etc.

I would go through the whole fuel system, and I would do a complete disassembly and soak of the carb. A little varnishing in the low-speed circuits could cause that. Do you idle the carb dry at the end of each day? You should.

Check your link-and-sync (ignition timing), and verify the adjustment of the pilot screw in the carb. If the carb goes a little lean as you cut the throttle, that could cause your stalling.
 
Thanks Paul,
The thing that gets me is that it only does it after a full throttle run, I wonder if it could be heat related.

Your comment on the fuel pump got me thinking, a year or two ago I had to replace the fuel pump. While washing down the engine I bumped the outlet and broke of the plastic barb fitting (only with my hand mind you!). At the time I was on holidays and couldnt get a new one, so I got an old 2nd hand one. Are the fuel pumps rebuildable?

Also any thoughts on the steam coming out of the lower port when flushing?

Thanks
Daniel

PS regarding the fuel, as I am in australia, and its a 2 stroke I wasn't aware that running it dry was recomended or wise as that would mean running the engine without lubrication?
 
Anything is possible. But these things are typically fuel related. You could try running with the cowl off for more air to the powerhead, and see if that makes any difference. Yes, diaphragms and valves are available for the fuel pump. Is it steam or exhaust coming out of the idle port? Actual steam is an overheat. It is always wise to run the carb out at the end of the day. As you still have 50:1 mix, the bearings don't go totally dry before the motor stalls.
 
Back
Top