2 Cycle Will Not Rev Up

[davey4000]

I have a Stihl model HS 80 hedge trimmer that will not rev up. The last time I used it about a month ago it ran fine. It cranks very easy, but when I pull the throttle it dies before it even gets up to 1/3 speed. I have changed the plug, cleaned the air filter and changed the fuel pick-up filter. It has new fuel in it. Since it ran fine the last time I used it I have not messed with the carberator adjustments. Any suggestions?

 

[Dmace]

Have you taken the carb apart and cleaned the jets?

 

[Shmudda]

Also make sure the spark arrestor on the exhaust isnt plugged up with black soot and carbon. Some manufactures put small screens on their mufflers that gum up and make the unit do that....

Craig

 

[Eagleview]

Along the same lines as Shmudda , check the exhaust for Mud Wasp nests . They just love 2 stroke mufflers .

 

[Bird]

So far, every time I've had that kind of problem with a 2 cycle engine, it's either been the exhaust plugged up, as already mentioned, or a simple carb adjustment. I've been lucky enough to not even have to take a carb apart.

 

[Donsyl]

i have to agree with the carb cleaning and or adjustment, and the plugged exhaust.............good luck.....Don

 

[natem]

I would clean the carb, just went trough this with a blower. Darn ethanol.

 

[davey4000]

Thanks for the advice. When cleaning the carb does it require taking it off or is there something that can be sprayed in it to do the job? I removed the spark arrestor and cleaned it. It was not very gummed up at all. It did not help the situation. It still will not rev up and stay running. The engine idles perfectly however. Now I'll out of town on business all week. I'll get back on it this weekend.

 

[ToadHill]

I had a similar problem with a Stihl chainsaw. I found the problem was the fuel line ahd gone bad due to ethanol just ate the rubber. One juel lint about 5 inches long $14.

 

[jinman]

I had a similar problem with a Stihl chainsaw. I found the problem was the fuel line ahd gone bad due to ethanol just ate the rubber. One juel lint about 5 inches long $14.

That's what I thought until I reread his first post where he said he had changed the fuel filter. If he did that and the pickup hose was deteriorated, surely he would have noticed. So I'm no longer thinking that could be the problem.

If your Stihl engine is like my chainsaw, there are two adjustments. One is just the idle speed adjustment. The other is the fuel adjustment. To set it properly, carefully rotate it clockwise to the the stop and then rotate exactly one turn CCW. Start the engine and adjust more CCW until the engine responds well with no stalling. Make very small adjustments. It doesn't take much to make a big difference with this screw. If it is adjusted properly, the engine will accelerate very well and have plenty of power to boot.