I have a 2001 Outback in the morning when before I start it up the interior smells like raw gas I checked the access door under the seat and it is sealed good. the gas cap is not cracked and is on tight. after the car is running the smell goes away and does not return till the next day. it sets at work for 9 hrs. but the smell does not come back. can anybody help the fumes are real strong and I am stumped.
You need to take it to a shop and have them locate the leak. This is potentially dangerous.
There may be a leak in the gas vapor recovery system that scrubs gas vapors from the gas tank. There are hoses that run from the gas tank to a charcoal canister in the engine compartment. If the hoses develop a leak you can get strong gas fumes inside the car. Sometimes mice will get under the car and chew the hoses, causing the leak.
Have someone do a smoke test on the gas tank/vapor recovery system. Where smoke comes out, there’s your leak. If you’re lucky it will be accessible without dropping the gas tank. If not, the tank may have to be removed in order to reach it, because the hoses come out of the top of the tank.
don’t know about your specific car. I regard it as an imminent fire hazard - take all precautions. Get a fire extinguisher outside near the car and inside the car in the front seat- they sell small ones for cars, maybe Sears had some. if you have a garage, ventilate vigorously, prevent vapor from travelling to pilot lights, water heaters, boilers, etc. Do not use a vacuum cleaner near gas vapor.
however, based on my Porsche 944, I can suggest sniffing around the fuel filler area inside the car. so that means where the cap is on the outside, go opposite that area inside the car. open windows, hatches, look for gaps - smell for them, try to isolate hoses and tubes, see if they spray upon being touched. You may need to pull up carpet or whatever - I did.
then look under the car in that area. can you look up into the areas you found above? find the fuel tank - look for the fuel hose going into a fuel pump, and out. are the lines in good shape? there are straps holding the gas tank on - how does all that look? look especially where the muffler is. One problem is that there could be hoses or leaks in between the tank top surface and the car body bottom surface (if that is how it is designed).
look at the inside of the tire in that area - any signs of trouble? the tire in that area on my car consistently was low, though it might be unrelated.
look under the car for the fuel lines - anything under the driver seat? something small but close would smell strong.
in my experience, the recovery system, oxygen sensor + leaks in the hatch were wishful thinking… that is, with a bad O2 sensor, unburnt fuel would be going out the pipe and back into the car.
merely looking at those things including the suggestions so far e.g. @jesmed can help get an idea of what you will be talking about when you call the mechanic - call, not drive, because you have to use a tow truck to get it there.