Tuning question?

[dodge man]

I’ve got a Stihl MS261, about 7 years old. It’s had what I’d call moderate use, far from worn out. I’ve never touched or needed to touch the tuning screws until recently. It starts fine and when cold and warming up no problem. If I don’t shut it off I can run a tank of fuel through it. The problem is a warm or hot start. It starts easy enough but it’s very difficult to get it off idle. Even just barely touching the throttle it wants to die. Hit the throttle hard and it does die. If you’re patient enough it will eventually run normal.

I turned the low screw out about a half turn, no help. Rather than randomly turning screws I thought I’d look for ideas. It’s warmer hear, I’ve been using it when the temps are in the 50’s to 70’s.

 

[RayIN]

When hot, the fuel becomes pressurized until it cools. IMO what is happening is this causes the engine to flood when restarted hot. Try loosening the gas cap, then re-tighten before starting to eliminate any pressure in the tank.
Might not be your problem, but costs nothing to try.

 

[dodge man]

When hot, the fuel becomes pressurized until it cools. IMO what is happening is this causes the engine to flood when restarted hot. Try loosening the gas cap, then re-tighten before starting to eliminate any pressure in the tank.
Might not be your problem, but costs nothing to try.

Thank you! The second I read your post I realized that is probably it. I took the cap off to check the fuel level when I was having problems and there was quite a bit of pressure.

 

[xyz123]

Also this time of year if mixed recently could be winter blend of fuel. Known to boil and create pressure in heat.

 

[dodge man]

Well taking the cap off didn’t help. Xyz123 hit it on the head, when I took it back it my shop after using it today the fuel was boiling.