My ‘67 Belvedere II gets a strong gas smell after I add fuel. I made sure not to overfill it. I had done this in the past and fuel leaked on the ground, so after driving it a bit, I let it sit outside so any residual gas could evaporate. Yesterday I added about $20 worth of gas to go to a cars and coffee this morning. I made sure I didn’t spill any and I stopped short of filling up all the way, but all last night, the garage stank of gas. Still does this morning.

Any idea what’s going on?

There are no puddles or evidence of leaks.

Thanks.

Well you need to find where it is leaking? You already have the clue. Rusty tank, bad filler tube, Filler tube or sending unit seal. Vent line off. Open port on an aftermarket tank. You need to add fuel until the leak is showing and that should tell you what needs to be done.

Check to see if the filler tube to tank rubber seal is leaking any.

On the 67 Satellite that I had several years ago when I installed TTI tailpipes and the factory tailpipe hanger brackets I had to push the gas fill tube just a little to clear and it started a very slight leak at the filler tube seal which had gotten hard over the years.

A new filler tube tank seal cured it.

The filler tube also is part metal tube and part rubber hose, so check it for any cracking.

The '66-'67 B-bodies are notorious for this. There are two small rubber 90 degree hose elbows for the vent and one large rubber 90 degree hose elbow for the filler tube. In addition to the seal grommet in the tank for the filler tube, there is a small grommet in the tank for the vent. One or more of these are leaking. The vent elbows, filler elbow, and filler grommet are all in repop. But if you are unlucky enough to have the vent tube grommet leaking, buy a new tank. I know of no way to successfully replace this. The repop tanks do not have this grommet and I can't understand why Mopar didn't use this approach to start with.

Sorry, I forgot to mention that the tank was replaced prior to me buying the car. I took a look at those rubber hoses ( what I could see from under the car) and they looked dry. I’m now thinking it might be the sending unit gasket. I need to jack up the car and investigate.

It may be as simple as thermal expansion.

Gas is typically stored underground, so when it goes from cool to warmer, it expands even if the tank was not 'topped up'.

With my two 383 cars, driving about 7 miles before bringing them home burns enough off.

The 318 car is happier that way after 10-12 miles.

Two things, first, you mention the hoses looked dry. Is there any evidence of gas staining on either? If they are leaking they won't be wet very long. If there is no evidence of staining, then I would agree with your thought of it being the sending unit. Second, the repop locking rings I've seen for the repop '66-'67 sending unit seem to be shorter than the OEM and doesn't clamp down as well. I've been cleaning and reusing the original rings.

If you added $20, that's not a lot. Without any puddles or drips, the smell will have to be vapor or a small leak.. IIRC, the float gauge flange sits most of the way up the back side of the tank at an angle. It could be that when you put $20 of gas in it, the level could reach the gasket there and start weeping out, until you use some gas and the level drops below the gasket. .. Gas could weep out around the gasket giving you the smell but no drips or puddles.

My '67 has never done that. Knock on wood.
- Art