Filling gas tank

You don't indicate if this problem is suddenly happening or has been happening since you started trying to fill the tank.

If it is a sudden change, then check the filler hose for a broken support/tie. Also, look at the pumps from which you're filling. Are they a different style than your pumps at home? If so, it may be the pump causing the issue - in this case, try changing the angle of the pump while filling, slow down the fuel speed while filling (hand hold the pump at a slow speed instead of using the pump lock), etc.

If it has been going on since you got the RV, then check for a kinked or deep bend in the filler hose (many RVs have a deep bend in the filler hose to maneuver around tanks, etc.; these bends can cause fuel to "spit back" when filling too fast).

The motorhome is new (750 miles when the problem showed up). I have only once filled without a problem. This was at a gas station with old pumps. Probably slow flowing and less sensitive.

Yesterday I was able to get under the motorhome.

The filler tube is metal and a smaller metal tube for venting runs down the side of the larger tube. It is then attached to a rubber tube that bends up and to the top of the tank.

I disconnected the rubber tube and gas ran out.

It is obvious that when the gas builds up in the fill tube it overflows into the vent line and accumulates at the bend in the vent line.

I am on the road and not able to make modifications but I would think that if I cut off the metal vent line and attach the vent to a rubber line that goes up and then down to the tank that gas cannot get into the vent line.

I am going to try disconnecting the vent line and then fill up the tank. If I am correct, the problem is strictly with venting. The problem is that I can't leave the vent disconnected until I get home.

If the experiment works, then I will probably have to pay to have the vent modified.

It looks like Four Winds (Thor) has never designed a motorhome fill/vent system in the past.

Sounds like a good plan. I had the same issue, turned out that my vent line support had come loose, letting the vent hose hang lower than the filler hose.

NTAR827,
Why don't you try going to a Chevy dealer or a Chevy truck dealer? Maybe they have dealt with this problem before and will fix it under warranty.

My Roadtrek 210P on a Chevy chassis had the same problem. I found that it was variable pump to pump and (as others have suggested) the slower the gas was pumped the better the results and that adjusting the angle the pump was inserted had a big effect as well. Many times over the years I just barely squeezed the pump trigger and took quite a while to fill the tank. I never put the pump on trigger lock (even at the lowest setting in the handle) and just gently squeezed the gas into the tank.

I suspect that with different emission control laws and subsequent filling nozzles in various parts of the country, you may well find this is less a problem in some places than others. With Roadtrek, it was a known problem and had to do with the modification (Class C) from the original Chevy design of the the fill pipe to the tank.

Paul

Before I have anyone work on the problem I want to better understand it.

Have not been able to get underneath the motorhome but will the first chance I get.

If I can't get the problem to go away, a Chevy garage is probably my first stop.

Nick