Fueling problems

[trmkvb]

I recently purchased a used 2015 Thor Four Winds MH, e450 with the triton V10. The MH had 20k miles upon purchase and we added another 3k since we bought it. I have never experienced any fueling problems until this last 1600 mile trip, at which time , during the last few fill ups, it took 30 minutes to pump 6-7 gallons of fuel into the tank. The fuel kept coming back up to the filler tube and shutting off the pump. I have disassembled and inspected the filler tube and vent line, all look fine. I have forced compressed air into the filler tube that leads to the fuel tank and it seems to be fine. I have forced air into the small vent line, released the air pressure and the air comes back at me from the vent line. I am thinking that this is where my problem is as I would think the forced air from the vent tube should go straight into the tank with no back pressure. Any help, thoughts with this problem will be greatly appreciated. Thank you

[jdoran1973]

Nothing on this yet? Perhaps the moderators haven't added any posts, but: I'd agree with your theory. Not sure if you can trace the vent line back , or give it a tug to see if it kinked up? I've seen threads where class A diesels had filling issues but not for an A or C. You may want to do a forum search to confirm.Another way to test your theory may be to add gas with a small gas can and a funnel. If the funnel is small enough to jet some air out around the spout, a gallon or so should go in fairly quick. Good luck

[Murf2u]

Originally Posted by trmkvb

I have forced air into the small vent line, released the air pressure and the air comes back at me from the vent line.

I am thinking that this is where my problem is as I would think the forced air from the vent tube should go straight into the tank with no back pressure.

Any help, thoughts with this problem will be greatly appreciated. Thank you

You are correct, if there is no air flow through the vent tube the tank will pressurize as gas is added and cause the 'burping' action you're seeing.

The usual culprit is something floating in the tank and getting forced up into, and blocking, the vent tube.

You didn't say but how much air did you force into vent line? A puff of air or a blast from a compressor?

[trmkvb]

I gave the vent tube a short blast of compressed air set at about 80 psi, (2-3 second blast).

[mel s]

Originally Posted by trmkvb

I recently purchased a used 2015 Thor Four Winds MH, e450 with the triton V10. The MH had 20k miles upon purchase and we added another 3k since we bought it. I have never experienced any fueling problems until this last 1600 mile trip, at which time , during the last few fill ups, it took 30 minutes to pump 6-7 gallons of fuel into the tank. The fuel kept coming back up to the filler tube and shutting off the pump. I have disassembled and inspected the filler tube and vent line, all look fine. I have forced compressed air into the filler tube that leads to the fuel tank and it seems to be fine. I have forced air into the small vent line, released the air pressure and the air comes back at me from the vent line. I am thinking that this is where my problem is as I would think the forced air from the vent tube should go straight into the tank with no back pressure. Any help, thoughts with this problem will be greatly appreciated. Thank you

trmkvb
A sag or droop in the vent line can cause that because fuel in the sag/droop prevents the air in the tank being displaced by the incoming fuel from exiting the tank, (similar to how a p-trap works).
If the air in the tank can't escape through the vent hose it forces the incoming fuel back up the fill tube/hose...shutting off the pump
I was able pull the sag out of my vent hose and cut it 5" shorter, thereby eliminating the sag and the slow fill problem.
Mel
'96 Safari

[Murf2u]

If you gave it an 80psi blast it's a lot bigger problem than just a drooping hose.

You're going to have to remove the vent line and see if there's a physical obstruction in either the tube itself or in the nipple that connects it back into the tank.

[mel s]

Originally Posted by Murf2u

If you gave it an 80psi blast it's a lot bigger problem than just a drooping hose.
You're going to have to remove the vent line and see if there's a physical obstruction in either the tube itself or in the nipple that connects it back into the tank.

Murf2u
Blowing compressed air through a drooping fuel tank vent hose will clear the fuel out of the sag, (but it only stays open/empty until the next time you pump fuel into the tank).
To permanently fix the problem the sag must be eliminated.
My 90 gallon tank took forever to fill for 8 years... for the 10 since I eliminated the sag it has always filled fast, (without constantly shutting the pump off).
Mel
'96 Safari

[okcnewbie]

On my daughters car I had to replace the purge valve solenoid. Her symptom was a bit different than yours but similar. Her car was hard to start after completely filling the tank. I believe you may even have two different solenoids for your EVAP system. A clogged canister could be your culprit.

Youtube has great videos on troubleshooting EVAP systems and the CEL codes.

[painterbill]

Several of us had similar problems with refueling the Thor 33SW Diesel SuperC, and the problem was the location of the vent line. The vent line would be lower than the fill tube allowing fuel to block the vent so the solution was to change the location of the vent tube and also rotate the fuel inlet so the vent location was on top. Easy to do by loosening the hose clamps on the fill and vent tubes, removing the 3 screws holding the inlet on the side of the coach then rotating the inlet so the vent location is on top then replace screws and re-tighten hose clamps. I had two tanks with inlets that I changed, made a world of difference, on one tank I shortened the vent hose a little but rerouting it also works.

[trmkvb]

Thanks for the info, I will look into these suggestions....all the vent lines look fine all the way to the tank so I will spin the filler neck around so that the vent line is on top, thx again for your help!

[camato5]

I had a similar problem on my Thor Tuscany DP while filling my tank, after several trips to the dealer it was discovered that the metal filler tube (where you insert the fuel nozzle) was installed upside down on the driver side of my unit. They unscrewed it, flipped it over and problem was solved.

[Murf2u]

Originally Posted by mel s

Murf2u
Blowing compressed air through a drooping fuel tank vent hose will clear the fuel out of the sag, (but it only stays open/empty until the next time you pump fuel into the tank).
To permanently fix the problem the sag must be eliminated.
My 90 gallon tank took forever to fill for 8 years... for the 10 since I eliminated the sag it has always filled fast, (without constantly shutting the pump off).
Mel
'96 Safari

Mel, the OP stated that when he blew a couple second blast of 80 psi air into the vent line. When he released the blower nozzle he stated the air blew back at him from his end of the vent line.

A drooping or kinked line would have, as you stated, would have opened. It did not. Thus there is a physical obstruction.

[mel s]

Originally Posted by trmkvb

I have forced air into the small vent line, released the air pressure and the air comes back at me from the vent line.

Originally Posted by Murf2u

Mel, the OP stated that when he blew a couple second blast of 80 psi air into the vent line. When he released the blower nozzle he stated the air blew back at him from his end of the vent line.

Murf2u
You're right.
His problem with slow fueling is definitely a different vent line/hose problem than than mine was.
Thanks for "straightening me out".
Mel
'96 Safari

[trmkvb]

Crazy, I took the MH to fill up with gas, pumped perfectly as though nothing ever had a problem. I'm hoping that it's not an intermittent problem as this creates a bad situation on the road, thanks to all of the replies and help!!