I have a McCulloch 2 cycle grass trimmer, model MT725; with MTD 31cc; engine family 5MTDS.0314MR:EM. Unit is about 2 yrs old with average household use. It does not accelerate from idle. I just cleaned the air filter, checked for blocked spark arrestor, made sure I have correct 40:1 fuel/oil mix, checked for fouled plug and correct plug gap, and adjusted the idle so trimmer head just stops spinning at idle. The unit cuts off as soon as i try to accelerate from idle. It has somewhat of a rough idle (very minor) with intermittent spurts: about once a second but not regular. Any ideas?

 

If you have adjustments on the carb, (Hi and Lo) back out the Lo 1/8 to 1/4 turn and see if it steps up. Carb cleaning or service may be required but usually just an adjustment will get it by.

 

Thanks BFHFixit. Your suggestion did the trick.
Although, I do not know which screw is Hi or Lo, I backed off one of them a 1/16th turn and got a little better response. Ultimately, I backed it off 1/4 to get desired operation.