Why Does Gas Shoot Out of a Jeep Wrangler Fill Tube?

Filling a Fuel Tank

  • When fueling a vehicle, it is overly simplistic to assume that the gas simply flows into the waiting fuel tank. As the tank empties, it is filled with a combination of remaining fuel and air. Since the fuel pumps at many gas stations create an airtight seal on the fuel fill tube, the air in the gas tank becomes trapped and cannot easily escape. To help aid in this process and resolve this conundrum, vehicle manufacturers like Jeep add a "vent tube" that allows the air trapped in the tank to escape.

Jeep Vent Tubes Tend to Stick

  • In normal operation, air trapped in a Jeep fuel tank will simply rise to the top of the tank and escape through the vent tube as gas is added to the tank during refueling. On some Jeep models, however, the vent tube can become stuck, or clogged, and prevent the escape of trapped air. This problem is not present on all models of the Jeep Wrangler, and even varies between Jeeps of the same model year and trim level.

Overflow

  • As fuel enters a Jeep gas tank with a clogged vent tube, the air can initially escape by forcing its way around the seal created by the gas pump nozzle. As the tank becomes increasingly full, however, the air must work harder to escape; at a completely full status, the air escapes violently because of the limited space available and often carries a small amount of fuel along with it.