ok if fine on ground going rich in the air or leen there is only one thing that regulates that and that is the metering spring and that works off the dirafram and that works off the vacuum pulse now u cant cange the dirafam or the vac pulse so whats left the spring on the metering neadle unfortunatly walbro do not check what pop off pressures as they were desighn for a CHAINSAWso varing the pop off pressure will normaly solve 99% off the problems the other 1% is other problems like the neadle high and low not correctly seated