Questions and Answers
Gas Cap And Idle Speed
Q. What does the tightening of the gas cap on a 1988 Olds have to do with the idling speed?
A. The gas cap on that car has a small vent to allow air to enter the fuel tank as the gas is used. If the vent is clogged or otherwise obstructed, air can not enter and a vacuum develops inside the fuel tank. The fuel pump has to fight this vacuum and could result in less fuel getting to the engine.
If it goes on long enough, the vacuum can become strong enough to actually collapse the fuel tank.
