March '20

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62 THE SHOP MARCH 2020 a filter in the vent line as it comes out of the vent solenoid in order to keep any dirt or debris from getting into the fuel tank through the vent system. You should also ensure that the place where the vent hose gets its air is a location that is as dry and debris-free as possible. One side benefit of properly venting a fuel tank is that we have had several cus- tomers tell us they no longer experience vapor lock problems they had before we addressed their fuel tank vent issue. Drilling extra vent holes into a vented gas cap or adding a vent to the fuel tank are other options, but this can expose the fuel in the fuel tank to outside air that has moisture in it, since the fuel tank breathes while the vehicle is not in operation. Anytime gasoline that contains ethanol is exposed to moisture, it increases the odds for phase separation. Phase-separated fuel is very corrosive to all the parts of an engine's fuel system and should be avoided. HENRY P. OLSEN is a carbu- retor specialist who has been rebuilding and tuning carbu- retor-equipped engines since the late 1970s, including helping to solve drivability prob- lems with the Speed Demon series of carbu- retors for the Barry Grant carburetor company. He is also involved in operations at Ole's Carburetor & Electric Inc., the family-owned auto parts business in San Bruno, California that was started by his father in 1954. These are typical aftermarket fuel tank vents. This gas cap from a 1979 Pontiac Trans Am had five vent holes in it from the factory, thus no fuel tank venting issues. This vent solenoid can be used to allow the fuel tank to properly vent when the engine key is on. The gray liquid at the bottom of the tube is phase-separated fuel. This picture shows the damage phase-separated fuel can cause. Proper Gas Tank Venting

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