gas smell inside of cabin

I have a 95' 4.0 that has a strong odor of gas inside the cabin. The smell is there whether the tank is full or low which leads me to believe it is not the filler neck, I can't smell or see a leak under the hood. I have a feeling it has something to do with the evacuation canister ( charcoal canister ). Has anyone had this problem?
thanks in advance.

I have not had a problem with the canister, but I did have a problem with a broken vent line that caused a gassy smell. You might have to check the lines that attach to the top of the tank for separation or deterioration. I also had a leak once in the very top of the tank, caused by accumulated salty sludge. It didn't leak significantly but seeped a little and smelled. It can be pretty hard to investigate the top of the tank but you can see at least part of it from forward and beneath and a mirror might help too.

Remember too that if there's a little leak in an injector or line, it can be hard to spot when the engine is warm, because it evaporates so fast. You may have to look pretty cloesely when it's running to spot it.

My 90 had a leak in the main rubber fuel line from the filter to the body hard line. A little hard to find because it didnt always leak and the fuel did evaporate quickly. The tell tale was the 'clean' spot on the frame in that area. The solvent properties of the gas dissolved all the grime. Replaced filter, rubber line & the rusted up hose clamps and on the way....

I had the same gas odor in the cab of my '88 4.0; one time it turned out to be leaking o-rings at one injector. The second time it turned out to be leaking at the junction between the bakelite connector and the injector body. Both times required sliding my finger slowly arround each injector, while the engine was running; you sense the wetness.

Thanks all for the suggestions.I gave it a quick look over today and still didn't track it down. I will do a thorough search., and let you know what it was when I find it.