A fuel fill system for use on a tractor having a lower fuel tank provided with an upwardly projecting fuel fill neck and an upper tank connected to the lower tank for flow communication therewith is disclosed wherein a filler tube is sealed against the fuel fill neck to define the inlet opening for the introduction of fuel into the lower tank. The filler tube is provided with a distal elbow defining an outlet opening positioned below the upper tank to direct gaseous bubbles within the fuel away from the filler tube to collect in said fuel fill neck or in other remote parts of the upper and lower tanks. A vent hole is provided in the filler tube near the inlet opening to allow the fuel to rise within the fuel fill neck as the upper tank fills. An adapter is threaded onto the fuel fill neck to capture a flange formed on the filler tube at the inlet opening to seal the filler tube against the fuel fill neck. A detachable cap is threadably received on the adapter to close off the inlet opening.