As accurate if not moreso than any other method. This will let you know how much fuel is in the motor when there is no feed. that way if it dies right away, you know its too lean. If it runs for a while its wayy too rich. If it runs for about 5-7 seconds once pinched fully, engine speeds up and dies clean your fine. if it stutters or sounds like it wants to die but doesnt, its too rich.