Sealing the vent hose may exacerbate the issue, as expanding fuel vapor needs to go somewhere (especially if the garage heats up). Short term answer is drain the tank (probably will help fuel cell life given the alcohol content these days.) Vapor leaks are not usually that strong smelling; I suspect you have a leak from the cell or a fitting. Be careful when tightening fittings into the bulkhead as it's easy to twist the fitting if you don't use two wrenches.

The boating industry developed an additive to combat the effects of alcohol on plastic/fiberglass fuel tanks. Has anyone considered whether that additive would protect our fuel systems?

Well, I know for a fact the fittings to the cell are OK! Put the cell back in, added about 3.5 gals of fuel, which seemed to be as much it would take?? it was empty?? Well still have a gas smell. Vapor if sealed stays in the tank as with all other FI cars, my blower, weed wacker, edger, powerwasher, and 6 5 gal jugs of fuel, and 3 other cars! One of the cars in the garage does not have a sealed cell system and I get No smell from it at all! Somewhere fues are getting out, however, the smell does not seem to be coming from around the vent vale area. I have not started the car yet,, I wanted to isolate lower fittings from those in the pressure lines. More later. Joel

Joel,
You being new to the car you are probably not aware of the fact that while filling the cell you need to open the vent valve to let the air out while filling the cell with liquid. This is commonly done by inserting a zip tie into the vent valve to hold the flapper open. We keep a zip tie attached to something nearby the cap so it is always handy. Do that and it will take the other half of the load you were expecting to put in.

Steve thanks, yep I know this tip, I was told not to use the zips as they can damage the valve and to use one of the body pins? It seemed the pin did open it but I will try further,,, that was the first time I tried to put fuel in!! Out to the garage to finish putting things back together after installing the ladder kit you sent! Joel

Did you ever find out what the problem was? I have a similar situation. I have two cars. One has an old cell in it and the other relatively new. Thought it must be the car with the old cell so took it out out didn't find anything. Drained both cars for the winter and smell went away. Put gas in the newer car yesterday and smell is back. Checked all the bolts and they are tight as per15 inch pounds. New cap still has the smell. Plan on pumping out the gas again and am thinking about taking the seat out and checking the cell for leaks but I doubt that is the problem.

I had the same problem with a brand new cell. No leaks, no wetness around gasket. Talked to ATL tech support and they said the cells "outgas" through the cell itself and can be smelly in a relatively tight, enclosed space such as a garage.

I now drain the cell as a part of my load-in at the end of a race weekend. The smell goes away in 2-3 days.

When I took out the cell, there was a very small bubble in the corner seam where the sheet metal step contacts the cell. When I pressed the bubble a very small amount of gas came out. My guess is that this would be enough to cause a leak. the dirt below this area seemed slightly wet and had a very distinct gas smell. The rest of the cell looks very good. In the process of replacing it because of the leak and the age of the cell 6 years! At lease 3 of those years we ran nothing but non-enthanol gas.

Also, the ATL installation instructions say 40 in-lbs on the bolts so you might want to re-torque.

I replaced the fuel cap and tightend all the bolts I could reach and that made a great improvement. The remaining smell seems about normal when I compair it to the scent I had with my club ford.
In january, I purchased a second car and plan to compair the smell when the weather gets warmer.
If there is a big difference between the 2 cars, I will pull the cell and see what we find. Thanks to all that replied to this post. Come on spring! CV