20 Most Recent Stihl Genuine 4229 007 1000 Vacuum Attachment - Page 5 Questions & Answers

could be connecting rod bearings are bad

go to a stihl dealer and order one.

are you pre-mixing the fuel? even though it's technically a 4 stroke engine the fuel still needs to be mixed. that's why they call it a 4mix engine. it may be junk now

carb could be dirty. or spark arrestor needs cleaned.

Check the Spark Arrester on the muffler. Usually an allen key to take off a section of muffler to get to it. It's a small Screen. They clog with soot and the engine cannot breath.

You need to change the small white plastic pawl, it is held by a r shaped spring clip, this provides the friction required for the pawl to be pushed out and engage with the starter cup, they are not the best starter systems out there.

Likely carburetor fouling, but can be other. If old fuel, dump and replace with fresh mix. Try using a fuel additive such as Seafoam, follow instructions... measure, don't guess. If new fuel and treatment does not clear the issue, then a more thorough cleaning of the carburetor will be necessary followed by a rebuild but the economics may be that replacing the carburetor is a better option. If clean/replacing carburetor doesn't clear the issue then it likely has a crankcase leak.

I and O are international symbols for on/off which I believe originally had more to do with electrical states " circuit closed = I" and "circuit open = O" but seems to been adopted for everthing that has an on/off. So I = RUN and O = OFF Following are instructions for the 044. https://www.stihlusa.com/manuals/instruction-manuals/#chainsaws

Follow the link please.

https://www.diyspareparts.com/parts/stihl/diagrams/ms181-c-be/834a60b6-3705-48c6-8415/

Check the plastic lines going to and coming from it. As they age they can crack.

Check fuel tank vent, loosen fuel cap as a test. By your description it is running only on the fuel available from being primed. So likely carburetor impulse air or diaphragm (carb rebuild or replace).