1973 - 1979 F-100 & Larger F-Series TrucksDiscuss the Dentsides Ford Truck
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Mil1on On your post (#13) in this thread you show a picture of your truck that you say has not been messed with.Your gas switch is labeled
AUX -on top Main -on bottom
Then in post (#17) of this thread you say that when your gas switch **** is in the DOWN position your running off the front tank and when your switch is in the UP position your running off the back tank.
Your truck uses the switch just like my dual tank truck does and you've proven my point In a dual tank set up the rear axle tank is cosidered the Aux tank and the frt tank is considered the MAIN nuff said
[u] Your truck uses the switch just like my dual tank truck does and you've proven my point In a dual tank set up the rear axle tank is cosidered the Aux tank and the frt tank is considered the MAIN nuff said
No, Not Nuff Said ....
You're not understanding what I am saying.
read post # 27 again
My Quote: Not contradicating it all.
It's in the terminology.
You're presuming that the position of the Knob means that tank that is being used.
ie: Knob up means use AUX.. Knob Down means uses MAIN Tank
But,Perhaps FORD is saying with the KNOB one direction OPENS the OTHER tank.
ie: Knob DOWN shows AUX tank use...Knob Up means MAIN Tank use.
I haven't proven your point.
You are assuming that the Fuel Tank KNOB Position is the actual tank in use.
What I'm saying is:
switch **** DOWN does NOT mean REAR Tank..It means Front tank (AUX) tank
switch **** UP means Rear Tank (Main) Tank
The Front Tank being the AUX - Mid-ship tank
The Rear Tank being the Main.
It's like someone reversed the Light switch in your bedroom.
switch UP usually turns the light ON
Switch down usually shuts the light OFF
In the Ford fuel tank switch it is maybe opposite.
Flipping the switch one way Opens the OPPOSITE tank to which the **** is placed.
We already knew that the IN cab tank of those years was considered the MAIN tank
In the 1973 Trucks with dual tanks (In Cab and and what Ford calls Underbody tank.)
If your truck is equipped with the Optional underbody auxiliary fuel tank in addition to the Main tank,the fuel level in either tank is read by moving the the fuel gauge selector switch to the proper position (What does proper position mean in terms of which way the **** goes? )
Fuel flow is controlled by the tank selector valve mounted on the floor to the lewft of the driver's seat.
On mine.... that switch on the dash is only to switch between which sending unit is sending the reading to the gauge....I have a valve on my floor with a labled plate stating which tank I am drawing fuel from....
Now then that being said...on my truck....the tank at the very back is the main tank and the tank closest to the cab is the aux. tank. I know this because I re did the fuel hoses one at at time myself and the fuel lines which corrolates to the aux. position on the valve I mentioned earlier go to that tank....and the line that corrolates to the main runs back to the very rear tank.
Originally mine was equipped with all three tanks seat...mid and rear but the seat tank was removed and those lines bypassed.
Long story short.....the aux. tank is the one closest to the cab in the box...and the main is the one closest to the tailgate. Just like in the diagram that Dennis posted from Ford. Anything other arrangement is most likely not stock and has been altered by a Previous Owner.
73 F 350 Super Camper Special
Proud So-Cal Chapter Member since the dark ages
New Member of the Kentucky Chapter
Nollaig has not posted since the 21st. saying he would fill up the rear tank and see what happens. Main... aux...who cares as long as YOU know which tank the guage is reading on YOUR truck.
As to nollaig's original post, I can think of only two reasons the pump works on one tank and not the other.One,as mentioned before,a crack in the hose preventing suction from that tank.or just as likely,a faulty switching valve stuck on the front tank.
It's possible to be reading the guage for the rear tank but the valve is stuck on drawing from the front tank.
Am I missing something?
Hmmm I can't understand the logic of if the rear tank is the main why is it smaller than the middle? I recently acquired a 1978 c/s f250 and pulled the tanks today and assumed the bigger tank was the main. But I guess common sense is overrated! On that note I was on Lmc truck looking up tanks and they really didn't seem to show a duel tank option? Any suggestions where to start looking for a rear tank?
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