only 15 gallons go in...

[audiquattro]

Please correct me if I am mistaken. The F-100's have a 20 or 21 gallon tank? Mine is a 1968. So far I have only filled up my truck twice and both times it will barely take more than 15 gallons. I have yet to completely run out of gas so I guess I don't know how much fuel is left when the gauge says empty. I do notice that when it says empty I hardly hear any sloshing at all.

Any one experience the same thing? If it comes down to it and I have an extra couple gallons when it says empty I am o.k. with that.

Thanks in advance!

Brad

[SteveC]

most in cab tanks are 19.5 gallons there was some emission tanks that were 18.5 but those wernt till later. The under bed tanks were roughly 25

[BobbyFord]

Strap a gallon can of gas in the bed and run it until you run out of gas.

[JMcTurnan]

But no flicking your cigarette ashes out the door, .

[fordman]

i think there were 3 size tanks avaialbe for these trucks in the cab. the exact sizes are on the site under fuel tanks.

what is happening is the fuel sender does goo all the way to the bottom of the tank. so the truck will always have a little gas at the bottom of the tank available for the suction tube to pick up barely get you to where your going when you reach empty. so if you are putting in 15. you still have soem fuel still in the tank because you made it to the gas station. the fuel gauge is a warnign sytem that you monitor while driving the truck. it isnt an exact measure of all of the fuel on board.

[flyboy2610]

But no flicking your cigarette ashes out the door, .

[audiquattro]

But no flicking your cigarette ashes out the door, .

No kidding, I think it overfilled by just a bit and as much as I like the aroma of gasoline it is rather strong with the filler that close to the door. Glad I don't smoke or have pyro tendencies...

[kaptnkaos]

That's exactly the reason I removed the in cab tank and run only the aux tank...
Besides, with the in cab tank removed, I have enough room behind the seat for my guitar...
It is very doubtful that I will ever have my truck far enough away from a gas station that I couldn't get there on 25 gal.

Not to snatch your thread, audiquattro, but mine does the same thing.
When I fill it up, it only reads 3/4 of a tank.
I just try to keep an estimate of how many miles I have gone, using 10mpg as my gauge...
Even though I get a little better (but not much) milage than that.

KaptnKA S

[70_F100]

Mine does the same thing, kaptnkaos. Never above 3/4 full.

I've tried three different sending units, so I'm pretty sure it's the voltage regulator for the dash.

Funny how many of us use "10 MPG" as our "gauge"...

[audiquattro]

Not to jinx anything but my truck seemed to be in the 12-13 range, about the same as my 08 Toyota Tacoma V6 4x4... crazy... by-the-way the Tacoma is for sale

[kaptnkaos]

Hey audiquattro,

1/2 tons will usually get a few mpg than 3/4 or 1 tons because of the weight difference and gearing.
When I had the 8' camper on my truck, I actually averaged around 12-13 on a trip.
With the 9.5' on it, I average around 11-11.7. I've never topped 11.7 with the 9.5' footer and usually average about 10-10.7 locally.

KaptnKA S

[babygoat17]

i got one of those 10 mpg mental gauges too. My in dash gauge does just the opposite reads about 1/4 tank when youre empty. I took the sending unit out and the float was bent downward. i guess the prev. owner tried to calibrate it or something.

[cdeal28078]

I don't think I have ever put more than 15 or so gallons in my 71 F100 either and I have accidentally had it low enough I figured I wouldn't make it. Mine is an emission tank I guess as it has the extra fuel line that loops up over the top of the tank.
Mine reads between 3/4's and full when topped off also. I always get that nice rattle from the sender unit since my rubber boot has been gone for years. Means I have gas so that is the only rattle that I don't try and fix.
Mine used to only come up to just below 3/4 full but one time I had the ender out and I bent the arm just a touch and now it is just below full.
clint

[george worley]

My guage only reads 3/4 when full I have changed instr. voltage regulater and sending unit I guess I need to bend the float arm a little. I too use the 10 mpg calculation . I fill up every 150 miles and write it on a post-it note that I stick on the ashtray.

[sideoilerfe]

Calibrating the sending unit isn't just bending the arm. Take apart the sender itself and you can bend the contact tab inside. That is the way to do it. there's a write up here than explains it. http://www.fordification.com/fuel-sending-units.htm