THE SHOP

March '20

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MARCH 2020 THE SHOP 61 drove the car into our shop, we heard the engine shut off on its own, then we heard a strange gurgling sound coming from under the hood. The problem turned out to be the vented gas cap that was accessed by opening a decorative flip-top gas cap that was not vented. When enough vacuum pressure built up in the fuel tank, the electric fuel pump could no longer pump fuel to the carburetor and the engine would die. The gurgling we heard was caused by the vacuum that had built up in the gas tank sucking gasoline back out of the carburetor's fuel bowl to relieve the vacuum that had built up in the fuel tank. Meanwhile, the Cobra's electric fuel pump problems were caused by the pumps having to fight against the vacuum that was building up in the tank due to insufficient venting. The fuel pump's windings would overheat and then short-out. HEAVY PULLING Many motorhomes and trucks that are used to tow trailers, as well as any vehicle that has had a high-performance engine transplant, may experience surging or a lack of power when driven under high- load conditions for an extended period of time. An example of this would be a vehicle pulling a boat trailer that loses power and begins to surge when it is driven up a steep grade that lasts more than a mile. An easy way to test for a venting problem is to drive the vehicle with the gas cap loose while duplicating the load conditions under which the problem occurs. If the symptoms disappear when this extra air is allowed into the tank, the problem is with the fuel tank vent system. FINDING THE CURE The method we recommend for improving venting in most gas tanks is to add a canister vent solenoid (such as Dorman part #911-800) connected to a vent tube installed in the fuel tank filler neck or at the top of the fuel tank above the fuel level. The vent solenoid should be energized when the key is on and the engine is running. We recommend both looping the vent hose so it can't syphon fuel out in case you overfill the gas tank, and installing An exploded view of a typical vented gas cap DEALER & DISTRIBUTOR INQUIRIES WELCOME 800.264.9472 • DesignEngineering.com ALL NEW - ULTIMATE PROTECTION BLACK TITANIUM LINE SLEEVING ALL NEW - ULTIMATE PROTECTION BLACK TITANIUM LINE SLEEVING • ORIGINAL TITANIUM MATERIAL IN GREAT BLACK LOOK • INSULATES WIRES, LINES & HOSES • ORIGINAL TITANIUM MATERIAL IN GREAT BLACK LOOK • INSULATES WIRES, LINES & HOSES Part# X402BT Lid Seal Part# X1663BT Fender Flare Trim HEADQUARTERS 6855 HERMOSA CIRCLE BUENA PARK, CALIFORNIA 90260 MIDWEST MANUFACTURING 1642 GATEWAY COURT ELKHART, INDIANA 46514 WWW.TRIMLOK.COM INFO@TRIMLOK.COM 800-543-8706 CALL US TODAY! Same Day Shipping on Thousands of Parts No Drilling! No Bolts! EASY INSTALLATION Experts in Plastic and Rubber Profile Extrusions TRIMS AND SEALS PEEL & STICK PEEL & STICK NEW! ® C M Y CM MY CY CMY K 2019 TL The Shop ad one 5-20.pdf 1 5/20/19 8:49 AM

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