I've had my SMB for several month's now. It's a V10 with the 46g. tank. As discussed elsewhere the 2009 van computer reads empty at 35g and that's all it will hold to fill up. So I had to know what I had left. I did what your not suppose to do and went ahead and ran it ,after it read empty, till the engine coughed. My usable is 43g. or 8 g. usable after the computer say's empty. It took 43 g. to fill it back up. In city, hill, worse condition driving for me thats about 60 miles extra. On the freeway that's about 88 miles extra. Hope this helps someone. RD

I do the opposite, and my tank is the reverse of yours although I unwittingly did the same thing based on the assumption my tank was like yours.

I kept getting about 35 gallons in, but it was a fill problem. SMB told me I had 8-10 gallons after E, or more accurately after driving out the 4 or so that cover E and low fuel warnings on my rig, so the next time I hit E I kept driving and nearly ran out of fuel (sputtered to a truckstop and managed to splash a gallon in with a big truck nozzle).

I can get the full capacity, but only by trickling the fuel in after the pump cut off. I recommend filling your tank in this manner until you can see fuel in the neck before trying the run out sputtering, and at that if you do bring your own gallon of Diesel or gas with you when you do. When I fill beyond the gauge the needle sits at full for the 8 to 10 gallons then starts to drop normally.

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it was good to be back

I have the same issue with my 2009, 6.0 psd, 46 G Transferflow.

Once the empty lights comes on, the computer say's that I have 50 miles left but arriving to 18 miles left to go the engine starts to cough.
The max I could put in is 38 Gallons. Tried it several times...

Will have to take the tank apart to see where is the problem, almost sure I have to cut the breather tube or/and modify the venting.

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2009 E350 window RB 6.0 PSD Quadvan 4x4 with EB pop top
2003 E350 ambulance 7.3 PSD Quigley
2007 Jeep JK for local offroad

The tank is what, about 2' wide by 6' long and flat as a board on the bottom. I don't know where the pickup tube is mounted but if it is 1-inch above the bottom that is over 7 gallons that you will never get to use. So are you sure there is something wrong?

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... Charlie
EV-2 build is now complete, (yeah right).
KZ6T

My comments were for after the computer says 0 miles left. I then have 8 g. Best

This has been discussed here (somewhere?) before, but here's my TransferFlow tank behavior:

For my 2004 Sportsmobile (gas), the gauge reads Empty when the tank is empty. (I found that the gas engine will start stumbling when you're minutes from running out of fuel.) When I fill my tank all the way, my gauge is pegged at "Full" until I burn the first 10 gallons of gas.

For some reason, this is not the behavior Sportsmobile told me I should have. They said it should immediately start decreasing from Full, and then read Empty for the last 10 gallons.

To fill those top 10 gallons over "full", I had to slooooooowly trickle in gas (1 gallon/minute) until I had my mechanic add a second breather tube.

-- Geoff

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2004 Ford, SMB 4x4, RB-50
https://octopup.org/sportsmobile

I wish mine worked like yours. When your computer says empty your empty.

I agree with you, the only thing I know for the time is that I am short of 8 gallons...
Or can not fill it up, or can not use them...
Any case needs to be solved in september...

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2009 E350 window RB 6.0 PSD Quadvan 4x4 with EB pop top
2003 E350 ambulance 7.3 PSD Quigley
2007 Jeep JK for local offroad

Are you sure you can't squeeze in more by "blipping" the gas pump handle? I know it's excruciatingly slow, but I could manage this (took 10 minutes to dribble in all 10 extra gallons) -- before messing with my breather tubes. I did this only for special occasions, like venturing into deep Baja desert.

-- Geoff

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2004 Ford, SMB 4x4, RB-50
https://octopup.org/sportsmobile

what brand of tank is it? I have a 2007 v10 an have been looking for a larger tank..