Barry Thanks. I'll save your post for the next time I mess up one of these with old gas.
Scott -----Original Message----- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com] On Behalf Of Barry Stark Sent: Wednesday, May 27, 2009 14:31 To: 'Mercedes Discussion List' Subject: Re: [MBZ] Ethanol Scott - It has been a few years since I have worked on many of those "pumper" carbs but as far as adjustments to the needle and seat, the parts that you would call the "float valve" in a float type carb, when you have it assembled to the point that you can view the needle seat relationship, the lever that bears on the needle should typically be parallel to the body of the carb. The last time I fixed a chain saw that had been sitting till the gas turned, the problem was simply that needle was stuck closed by varnish. A good cleaning and it worked fine. Sometimes the diaphragms just get dried out and crack. Gotta make sure there are no perforations or tears. You also need to make sure that the hoses are good or they may be sucking air. The reason that these carbs are often referred to as "pumper" carbs on the 2 strokes is that they have an extra diaphragm that uses a pulse from crankcase pressure to act as a fuel pump. Can't have any leaking gaskets. You need to make sure that you have cleaned the passages to the high speed and idle fuel circuits as well. Screw those adjustment screws in all the way making note of how many turns. Don't force the adjustment screws, just lightly bottom them. After you have verified clean passages and reassembled, open the two screws about the same place and add about a half a turn more open and final adjust after the engine is running. BTW, you don't really want to run 2 stroke engines out of pre-mix fuel in an attempt to empty the carb because the oil is in the fuel so you are running the engine out of lube as well. You'll probably never get all the fuel out of a diaphragm carb anyway, the engine will starve and quit before that happens. Barry On engines with a fuel shut-off (like my generator and lawn vac) I try to run the carb dry between uses and that helps too. On the other hand, I've never fixed a diaphragm-type carb (like on chain saw or blower) permanently despite several attempts; these may require special tools to set the diaphragm or maybe I needed to actually replace parts. Does anyone know the trick for these diaphragm carbs? Scott _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
