Walbro Carb Wizard

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shorthunter

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I am looking for a little advice on a walbro carb that I have modified for fitment. The carb in question will not feed the saw enough fuel. It seems to feed the saw plenty of air but I am almost three turns out on the high speed screw and I cannot get the saw to four stroke for an extended period of time

Could be a vacuum issue or it could be as simple as drilling out the carb. Right now the saw will run pig rich for 3-4 seconds before the rpms start to climb. Within another 3-4 seconds the saw will be screaming like the toddler you saw in Walmart yesterday
 
I had the same issue going on at the Pa. GTG with my 036 (zama). Someone way smarter than me diagnosed it correctly. Dozer Dan said he thought the pump side diaphragm was getting a little stiff and not pumping at a high enough rate to feed the saw. As he suggested, I put an oem kit in it and issue was resolved. I don't use fuel with ethanol in it, but it is known to cause diaphragms to stiffen up. This saw was bought used, so who knows what was run in it in the past? I do know this, it wasn't all that old. We don't have the whole story on your saw so everyone is just stabbing at your problem.
 
Rebuild the carb with a new kit or you'll never be able to eliminate that possibility. It may be that the saw it came from had stronger impulse to get the most out of it.
 
:crazy2::eek::yes:
Sounds like a Husqvarna K760 cutoff saw when the impulse hose has gotten disconnected. Leans out and idles high. Then whIMG_1650.jpg en you goose it, it'll fall on it's face and die.
Make sure your gasket isn't backwards, or blocking the impulse port. Or the port on the needs drilled to feed the signal to the pump. some times they look drilled, but they aren't.
Obvious to some, but make
sure the impulse isn't fed through the intake boot and your carb has a nipple hose connection.
Do a pressure/vacuum test to rule out a leak as HarleyT guessed.
 
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