Subject: smell of gas
Question: 97 Mitsubishi Eclipse.
When driving over bumps, infrequently smell gas after going over a large bumb. Car is not leaking gasoline and the smell occurs only on bumpy roads
Answer: Bernice,
This could be as simple as a gas cap with a bad seal. Find out if you smell gas more when your tank is full as opposed to when your tank only has a quarter of a tank. If the smell of gasoline is stronger when driving over bumpy roads, and your tank is full, odds are your gas cap is not making a good seal. You can go to pretty much any auto parts store and buy a new gas cap. They are pretty universal. If you want a new one like the one that came with your car, you can order one from a Mitsubishi dealership.

If a new gas cap doesn't fix the problem, have your fuel system checked out by a mechanic. Even just the gas fumes are very dangerous. Though they may not ignite, they can make you dizzy. You may not be able to see any leaking gasoline on the ground under your car, you may have a leak in the engine. Its possible you have a cylinder that's not firing when going over bumpy roads. That could be due to bad compression. You could have a loose or faulty spark plug. When the spark plug doesn't fire, the air/fuel will not ignite inside your cylinder compartment. That would lead to a build up of gasoline, and you would smell it inside your car for sure. But try the cheaper fix first by buying a new gas cap.
Good luck!