DIAGNOSIS Bar oil is siphoning from the tank through the oil pump. The most common point of failure is the oil tank vent.
FIX Locate the oil tank vent. It is a small, often green, one-way valve near the oil cap or filler neck. Remove it. Blow through the valve to check it only allows air in one direction. If air passes both ways or it is cracked, replace the vent valve.
IF THAT DIDN'T WORK The oil hose connecting the tank to the pump may have a crack or a poor seal at the fittings. Remove the side cover and inspect the clear hose for leaks, especially where it connects to the pump nipple.
HEADS UP Do not store the saw on its side or with the bar nose lower than the tank. This accelerates siphoning. Always store it upright or on the correct side as indicated in .