Echo Weedeater SRM 230/231

Greetings,

I have an SRM 231 that bogs under full throttle pull. Here's what I have done so far to help troubleshoot the issue:

Replaced fuel filter and line, tank breather and line, primer bulb, air filter, fuel/oil. Cleaned plug, spark arrestor and carb.

No change after doing above.

Process: Slow throttle pull seems to help, but still not topping out RPMs and runs rough. If I back off throttle to about halfway, seems to pick up RPM and runs more smoothly.

Here's the kicker , if I cover the intake of the air filter housing (bottom vents), runs perfect reaching max RPMs??? It seems as if it is running too lean???

Ideas? Suggestions?

 

Replace or rebuild the carb.
Find a place that sells nonethenal fuel.

 

Sounds like the high speed mixture screw needs to be backed out 1/8 turn or so if it has one on this model.

 

Thanks for the replies,

The carb on this trimmer is a Zama RB-K70A. I don't see any user adjustable screws other than the throttle adjust. There is a jet that is covered by a factory cap that I have read can be removed to be cleaned, but that was for a different symptom.

The thing is that it was working great a few weeks ago...

If it runs at high RPM under air starvation (when I cover the air intake with my hand), does that mean it may be running too lean? Could a damaged diaphragm / pump gaskets on the carb cause this type of symptom by letting a bit of air in?

I guess my next option would be a carb rebuild kit...
or run the trimmer with the air filter mostly covered

 

I wouldn't continue to run the trimmer. Damage can be done with a lean mixture.
I would advise a good carb cleaning or replacement, as mentioned.
Another, more serious problem, could be bad crank seals although, in most cases, with bad seals, the engine will not idle.
If seals are bad, that's a pretty big job, hope it is a carb issue.

 

Yep, the carb needs cleaning.

 

Would PB Blaster engine tune up spray work on a 2 cycle engine? Just curious. I like it for my lawn mower, tiller, and other 4 cycle engines, just not sure on the 2 cycle.