Small Engines (Lawn Mowers, etc.): Poulon pro PPB200E weed eater, zama carb, thin bead

Question
First off let me give my most sincerest thanks for your service to the country. My family and I appreciate the freedom people like you protect.

Now to my question. I cannot get my weed eater to start. Or if it does it will not stay running. I have replaced the hose's, sprayed down the carb with ether, checked the exhaust, and cleaned out the filter. It seems odd to me that when I do get it to show life, I have the High side almost completely backed out and the Low side about 3/4 backed out. If I mess with anyone of these settings the engine stops and I will not get it to start again. When I first bought the dang thing it worked for maybe half a summer. Then evreytime I pushed the throttle the engine would bog down. After that I had a hard time keeping it at an idle. Now I cannot get it to really run at all. Any Suggestions?

It has a ZAMA Carb. Model CU1
31cc engine
serial # 05342n700526-1


Answer
How old is the trimmer?  Have you checked the compression?  You should have at least 100 psi for the engine to run properly.  About 125 psi is normal.

A common problem with your model is a leaky oring on the rear engine o-ring.  You will have to remove the to access the o-ring.  From what you described, setting the carb rich, you make have an air leak.  Once you have access to the o-ring, clean the parts with carburetor cleaner and then use some Permatex #2 non-harding sealer to ensure the o-ring is sealing.  Just apply a thin bead of Permetex #2 to the rear engine case, install the o-ring and then re-assemble.

While you have the rear engine cover off, check to see if there are any other signs of an air leak.  Usually the air leak can be spotted by looking for dirty/oily places between parts, where then are assembled.
I have also found a few metering levers that were not at the correct level cause your problem.  Here is the Zama carb manual which describes the metering lever height adjustment procedure:

http://www.zamacarb.com/tips.html

Basicly, the metering lever height should be flush with the carburetor body.
Let me know if sealing the o-ring and metering lever adjsutment solves your problem.  
Eric