Toyota seanna smeel gas coming out from heater?

There is a fuel leak in the engine compartment. Have a mechanic look at the engine.

One of the lines is leaking or a hole has developed in the top of the tank. Time for a replacement.

i would get this checked immediately. i had the same problem and there was a major leak in the fuel lines and the car could explode at any time. i was sitting on top of a ticking time bomb. Dealer...

Pay attention to your gas heater, if the leakage is at night you can die intoxicated. Keep such apparatus under continuous maintainance.

if it is liquid gas, then it is a probably a dead cyl or a stuck injector. this is bad, get it fixed. but it may just be water, this is natural, dont worry about it.