ms180 floods out

[b7100]

I have a Stihl MS180 that floods out when you try to let it idle. Starts and runs fine at higher rpms but when you let up on the throttle it loads up and floods out and won't start. Let it set a while and it will start right up. I've had the carbureter apart several times and used carb cleaner and compressed air to clesn out all the little holes. It seemed to help a little but it is still loading up. Any help would be greatly appreciated.

 

[Stihl #1]

A pressure test will verify if the inlet needle is holding or not. Remove the carb and hook a tester to the inlet fitting, pump no higher than 10 PSI and it must hold steady. If it is leaking, immerse under water and see where the bubbles are coming out. If out of the venturi the needle is not sealing, or the inlet lever is set too high and the diaphragm is holding it open.
Let me see if I can find some pics.

 

[Sprig]

Stab inna dark, could the float-valve be sticking, like a bit of varnish or piece of crud holding it open a hair?

Just a thot



Serge

 

[Lakeside53]

Blasting with compressed air can ruin the outlet valve, and other check valves if your carb has them.

 

[Stihl #1]

Use some kind of low pressure tester, hook it up like this:

and if the pressure does not hold put it under water and see where it is leaking, most likely out the venturi meaning it is the needle. Pull off the metering cover and check that the inlet lever is flush wit the carb body:

If all this checks out then it may be the main nozzle check valve leaking, which will cause lean running at idle, so it will idle fast and then maybe die. You said loading up which I think you mean too much fuel, rich, making it die.

 

[Stihl #1]

As Andy said, the high side check valve is very delicate and harsh cleaners and high pressure air may ruin them. I only use a brake kleen type spray as it is milder than choke spray, and blow out gently with low pressure air. Never soak in solvent or Gunk.
Ultrasonic cleaners are Ok but I have never had a carb with stuck (varnished) check valves work properly after even an ultrasonic bath. When tested the check valves always leak.

 

[Lakeside53]

I guess it depends on what you use in your ultrasonic cleaner, but yes.. conventional fluids l won't touch varnish...

 

[b7100]

Thakks guys. I put in a new carb kit and it runs like new.