46 gal gas tank but have never added more than 35 gal

[Ruthless]

I have a question concerning our Transfer Flow 46-gallon replacement fuel system for our 2012 Ford E350 SMB which has puzzled us on several trips. Gas gauge goes down approaching E until we get a beep and a ’50 miles to E, Low Gas Warning.” BUT we’ve seldom put in more than about 30-gal, which gives us about 300 miles. Our regular mechanic thinks that maybe (1) the pump doesn’t reach the bottom of the larger tank or (2) the gauging system is somehow ‘set’ for the original 35-gal tank. In any case, do we have 11 gal somewhere!? Can the engine access this fuel and it’s just that our gauge is not accurate? We’re tempted to just run it to Empty on the gauge around here and see if it keeps running! Sure would be nice to know if we have some reserve fuel in there!

[REF]

There’s what’s called the “hutch mod”, but yes you would have about 10 gal left in the tank after the light goes on.
I found that out when I tried to run my transfer tank dry to drop it, light went on, drove for another 20-30 miles figuring there’s a few gal left, but was surprised to see what I gathered was about 10 gal still in there.

[bigriver]

On our 2003 diesel with 46 gal tank we usually get 125 +- miles before the gauge points to full, we'll get another 300 - 330 before light comes on and there will be 12 gallons left in the tank at that point. we've gone 635 miles before fill up ONCE... because of what I called a gross miscalculation and the navigator called being an idiot (she's almost always right). Talk about pucker factor...

[86Scotty]

"We’re tempted to just run it to Empty on the gauge around here and see if it keeps running."

That's exactly what I would do. First, is this a diesel? You don't want to risk running a diesel out of fuel so don't do this if it's diesel.

If it's gas fill up the van and also a 5 gallon can. Reset the trip odometer and run it til empty and calculate based on mileage when it runs out. Should be easy to figure out if you know approximately about what MPG your van gets. When you run out, refill from 5 gallon can, head to fill up and then you'll have learned something.

But I can pretty much tell you your float and arm weren't recalibrated (meaning bent) to reach the bottom of the tank when they installed the TransferFlow. I'd be pretty pissed if I was the one who paid them to do the job but that may not be you and it's water under the bridge now anyhow?

[geoffff]

The fuel gauge isn't recalibrated for the larger tank.

My 46 gallon Transfer Flow (gasoline) tank behaves the other way -- it shows "full" for the first 10 gallons.

[Ruthless]

It’s gas not diesel. We bought the van used. We’ll have to try your suggestion.

[Ruthless]

Thanks all, good to know ��

[rallypanam]

Originally Posted by 86Scotty

"We’re tempted to just run it to Empty on the gauge around here and see if it keeps running."

That's exactly what I would do. First, is this a diesel? You don't want to risk running a diesel out of fuel so don't do this if it's diesel.

7.3s are easy if you learn how.. don't ask me how I know.

Remove air cleaner and crack open fuel filter threaded cap.. Cycle ignition (to trigger fuel pump) until diesel comes out of filter cap. Tighten cap, replace air cleaner, start van and drive away.

[HIGHCOUNTRYMIKE]

Ruthless,
I have the 2003 7.3 and 46 gallon tank.
When my Low fuel alert comes on it means I have at least 10 gallons in the tank.
I have asked around about how much is usable but no definitive answer. My rule is that I have at least 100+ miles left.
I think the most I have ever pumped is 39 gallons.
I get an average of 15 mpg when driving less then 65.......did 22.5 when max was 60 mph.
I just live with the fuel gauge I have. I understand it....you don't ever want to run a diesel dry.
I'm a "if it ain't broke don't fix it" kind of guy. I have 313,000 on my 03 SMB. Working on the next 300,000.
2003 E350 Ford 7.7 SMB EB50 313,000 and planning my next trip to UTAH, WY and CO.

[shenrie]

Originally Posted by HIGHCOUNTRYMIKE

I have the 2003 7.3 and 46 gallon tank.

I think the most I have ever pumped is 39 gallons...

^^^ ditto for me.

Originally Posted by HIGHCOUNTRYMIKE

When my Low fuel alert comes on it means I have at least 10 gallons in the tank.
I have asked around about how much is usable but no definitive answer. My rule is that I have at least 100+ miles left.

^^^ not the case for me. Last time I let it get below a 1/4 tank anticipating the warning light, it went into limp mode. Added some go juice and it’s been fine since, but now I’m gun shy below a 1/4 tank.

I plan on doing the hutch mod if I ever drop the tank, but with the wife’s condition we are rarely able to go further than 3 hours at a time, so it’s really not currently an issue we can’t fully utilize the bigger tank.