CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Gas cap whoosh missing

Ihave a 1989 Toyota pickup whosr whoosh is missing upon removal of the gas cap. Cap replaced, no help. What is the problem? Is it serious?

I miss my '89 Toyota pickup.

The only problem is that your tank can now breath in freely and no longer maintains a slight vacuum when operating. Ardent supporters of the Clean Air Act might be appalled, because you may now be allowing some tiny amount of hydrocarbon molecules to evaporate freely into the air…a free pathway in will likely also be a free pathway out. Personally, I don’t see it as a problem as long as the car is running fine and you don’t smell any gas fumes inside or outside the truck.

The exact reason may be a couple of things. An open pathway via the charcoal canister comes to mind. A cracked or dried up and fallen off 19-year old rubber connection or hose is another possibility.

Or perhaps the gas is just draining back into the tank from the float bowl drawing air back through the venturi orafice and the vacuum is being relieved that way. Has it taken a few tries to get it started in the morning lately?

Persoanlly, I’d just keep smilin’ and enjoy the ride.

I would tend to agree with the previous poster. If you really miss your whoosh, you might start with following the lines going from your tank to the evap cann somewhere up front. There is probably an open in the vacuum lines from being cracked, jerked loose, or otherwise open to the environment. If your PU was newer, you’d get a check engine light for your evap system not being sealed… But since you probably do not, you are only losing some vapor, hence probably less than 1 mpg, so now you have to decide if your lack of whoosh is serious enough to warrent the time and energy you’ll spend chasing down the missing whoosh.