QuestionI have a Craftsman chain saw (358.350180) I am working on that stumps me. It has a Walbro WT391 carb.
After a good overnight solvent soak for the carb, compressed air blow in all holes, a thin wire to clean all holes, and a carb re-build kit, it starts and idles like a dream (LO screw and idle adjusted). As soon as I add a small amount of throttle, it revs up, a little more throttle and it dies. If I goose if from idle to WOT, it revs for 1/2 second, then dies. It seems to be getting too much gas and flooding out. When I adjust the HI screw, there is no change at all until it is screwed out so far that the saw dies
I have tried many things; I have a Walbro gauge to adjust the metering lever. I have adjusted the metering lever higher, then lower than the gauge tells me. I have tried placing the metering diaphragm against the carb body under the thick gasket, then also placing the thick gasket against the body with the diaphragm on top (as Walbro says to do). No joy. There are no holes in the fuel pick-up line, and the muffler/spark arrestor is clear.
Any thoughts would be appreciated.
Answerrebuild carb to Walbro specs. If you turn the high speed screw in all the way what happens? It should die. Turn the screw out 2 1/2 turns to start and adjust from there.
Have you checked things like the primer and primer line? Have you tried a spark plug the next range hotter? Did you remove the muffler and check the exhaust ports for carbon build up? When cleaning look into the cylinder to see if there is any scoring. Have you tried running it with out the arrestor? The other thing I would check is the insulator block for warpage. That is the block between the carb and block. Hope it helps.
