Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

I smell gas

I have a 2004 Mercedes SL500 convertible and every time I get in I get a hit of gasoline smell. I’ve had two mechanics look at it and they can’t find a leak. Any suggestions?

Take it to a third mechanic and have them inspect your charcoal canister. It’s probably saturated with raw gas. BTW…any mechanic that does not inspect the canister when a gasoline smell is detected is not much of a mechanic at all. That’s the first place I check.

And then have a smoke test done. There may be a leak in one of the gas vapor recovery hoses coming from the gas tank, and those are impossible to find without a smoke test. The mechanic will pump smoke into the gas tank, and the smoke will come out where the vapor leak is, allowing visual detection of the leak.

If it turns out to be a saturated charcoal canister, you might consider why it is saturated. It could be because you or a previous owner filled the gas tank past the first click. Topping off is more likely to dump gas into the canister, shortening its life.

Do you smell the gasoline odor before starting the engine, or after? If after, it could also be something amiss with the fuel injection system pumping in too much gas at first. It is supposed to inject a little more gas during “start” to richen the mixture enough so it will start reliably, but it might be overcompensating for some reason. The extra gas will go through the motor unburned and come out the tailpipe, and you’d smell the odor. Another idea is a leaky injector which allows fuel to leak from the fuel rain into the intake manifold when the engine is off. Usually you’d notice this though as the engine taking longer than normal to catch and run during the starting process, especially after the car has sat a long time.