The Fuel System of an air-cooled Volkswagen is not a complicated System.
But, there are some Fuel Issues which continue to plague the VW Community—some of them easily resolved with a little bit of thinking and work. These are things which most of us can do ourselves.
First, rather than running to all of the forums on the subject, it’s time to sit down to consider how the Fuel System of our Beetles works.
CAUTION: When working with Gasoline—ALWAYS work outdoors and away from any source of flame or spark!
The Fuel Tank:
Complaints about Gasoline Fumes are common. Two things usually contribute to Gasoline Odor in the Trunk. This Odor often penetrates to the Cabin area.
Let’s talk about the Tank Filler Neck. Note that there is a tiny Tube coming off the Neck
pointing towards the left side of the car. By removing the Gas Cap and looking into the Filler Neck, we can see the Tube protruding into the inside of the Filler Neck. Where it protrudes, it is slightly pinched. This is to limit the amount of liquid gasoline which can escape through the Tube. A tiny Rubber Vapor Hose (N203531—ID-2.0 mm/OD-3.5 mm) is pushed onto the tube where it exits the Filler Neck. It needs no clamp since it fits tightly and there is no pressure upon it. (Note: Vapor Hose also may be marketed as Vacuum Hose.)
The Vapor Hose loops back towards the driver, then back again to the front of the car where it is pushed through an opening and allowed to dangle several inches beneath the car. Thus, any Gasoline Vapors will exit beneath the car and will not escape through the Trunk area and into the Cabin. If the Vapor Hose is missing or improperly routed—Gasoline Vapors will permeate the Trunk area and pass into the Cabin. Be sure that the Hose is present and routed through the hole to beneath the car. 2 Hose Clips (111-201-261) keep the Vapor Hose stabilized on the Cowling Loop.
If the Tank Filler Neck Tube becomes plugged, gasoline will not flow properly from the Tank Outlet. Also, make certain that the Vapor Hose is not pinched or plugged.