In my 1973 Ford F250... which tank is the aux and which is the main? They are both on the driver's side the front one is locking and the back is not. I just bought the truck and put gas in both so I am not sure which is which. Thanks.

 

Depends on the year,,, my 73, the MAIN is the rear tank, the AUX is the front one, on my 77 the MAIN is the one in the cab, and the AUX is the rear one. Just drive it till one is empty, or both, and then fill up just the front one and see which one says full, and runs the truck. I have talked to both original owners, AND my Granpa who retired from Ford, and had a dealership, and from what I have garnered, it depends on which one was the factory STANDARD tank, and what ones were the optional.

 

I did not think they put a tank inside the cab in 77 Ford trucks. I have a F150 Custom 2wd regular cab long-bed truck which has the two rectangular gas doors on the bed, but it only has the long inboard tank that runs along the inside of the frame. The rear tank was never installed from the factory, so this would lead me to believe that the front tank would be the main and the rear would be the auxiliary. Is your 77 truck a 4x4? I am thinking they may have put front tank inside the cab on the 4x4 trucks due to drive train clearance issues.

 

front tank is always the aux,the rear tank is always the main,

 

This would depend on which way the last person to work on the fuel lines routed it. Mine is routed straight from the front tank to the motor. If the PO hadn't included the fuel lines to the switch, I would never know which way was right. So this has had to have happened before. But one would assume normally the closest to the cab is the main. But when is a Ford normal?

 

Yes my 77 is a 4X, and that could be,,, not sure. It is a SB (shortbed) so that may also be why it is in the cab. My 73 only has the 2 in the bed,,, so who knows?!

 

Yeah, that's the way I see it too. :)

My rear tank was standard equipment in the '75 F150 and ordered mine
with an extra "mid ship tank" (as Ford calls it) and that's the "aux tank"
according to the switch and the Shop Manual and everything else I read.

But yeah, it's not about -where the tank is- it's about which one was the
optional tank. As ya read the Shop Manual it seems pretty clear that was
the thinking at the time.

Alvin in AZ
ps- the coolest thing about an in-cab-tank is how easy it is to
pour gasoline into it from a gas can, no spout or tube needed ;)
pps- had a Ford bumpside during the "gas shortage" of '73 and
that feature on it was cool! :)
ppps- there was a couple times I took my own car on RR signal
trouble calls because of the gasoline situation, talking about an
easy way to **** off the wife that had sat in line for hours to get
that gasoline! LOL :)

 

Last year for the In-Cab fuel tank = 1977.

 

Cool. :)

I can't remember if it was offered in the '75 F150 tho. :/
All I can remember about it is I wanted that space for other stuff!
And also seems like the "mis ship tank" is bigger anyway?

Hmmmm... maybe it had more to do with the short bed pickups'
only factory offer to get an extra tank? Since I wanted the long
bed anyway... didn't enter the picture? :) {shrug}

Alvin in AZ
ps- my pickup can go 600 to 650 miles without stopping for gas.
...me? I can only go about 500 miles without stopping! LOL :)
pps- I never-ever ran out of gas in my pickup in 33+11/12 years.

 

Crazy thought, was it possible to have ALL 3 tanks on one truck?

Josh

 

Crazy people think alike. ;)

The electric valve (and the older manual valve) and the fuel gauge (and/or
tank) switch are two position so I always figured it was never intended to be
setup with three tanks. But a dealer or an individual could rig up something. ;)

Be interesting to hear what Bill's got to say about what he's seen. :)

There's been a few times I really could have used another 5 gallon capacity
or so.

Alvin in AZ

 

Just imagine, the extra capacity 38 gallon rear tank plus what are the other tanks 25 for mid-ship and 19 for the in cab?

And if your engine can muster 15 mpg on the highway, your good to go for 1230 miles!

Josh

 

Not sure if it was factory, but my friend growing up in MO, got his grandpa's old 71 or 72 pickup, and it had 3 tanks, all working, in cab, and 2 in the bed, worst part was he was such a cheapie, he would only put in $5 a time in the cab tank and was ALWAYS running out! So after payday one day, I forced him to go fill ALL 3 tanks,,,, he drove for months it seemed! Course, then we were paying .40 cents a gallon! Could get a full tank in my 66, and a can of cope for less than 10 bills! Hell now I think just a can of cope cost that!

 

Not on F-250 Highboys or certain chassis cabs.

The in-cab tank is tha main tank on those, but it still would be the front one , this is because they never had a stock rear tank.

Otherwise you are correct.


And to make things more confusing....
1980-1986 is the exact opposite, front is the main on those.

 

There were aftermarket places that installed saddle tanks for dealers and individuals back in the 1970's early 1980's. This was very popular when the gas crisis was going on, and the shortage of gasoline.

My friends 1971 had three tanks. The two factory tanks, and a 35 gallon aftermarket saddle tank mounted to the right side, simular to the factory saddle tank which was added to the truck in 1974.