second tank switch

[mouse]

I have a 71 f250 sport custom camper special and I have 2 switches for my tanks, the one under the dash is to switch witch one goes to the gauge. what I am confused about is the one on the floor because all it said is main and off, it don't say auxiliary. the second switch is frozen and I don't know how to turn on the auxiliary or if it is already on.

[fordman]

so its a two position switch on the floor? look underneath the switch. and see how many tubes are going in to the switch. you can then also see where to turn the switch to to get it to the aux tank. there will or should be only one outlet going to the fuel pump. you can remove those floor switches and clean them up and get them to unfreeze.

[Dragon]

Yeppers they clean up real well. Also on that 71 Dash switch it is 2 Dual pole switches. One of the 2 pole switches switches the gas tank sender to the gauge the other side can be used to switch a pump relay for switching between two electric fuel pumps. I am taking out my floor valve and going the 2 electric pumps route with one way check valves to keep one pump from back flowing into the other.

[mouse]

my floor switch has 3 hoses. dragon that ideal is nice but I rather have 2 electric fuel cut off valves, they can be found on 90s cougars

[Dragon]

Mine does too. The cutoff valves are a nice idea .

[willowbilly3]

Ford had a very simple tank switch valve for years, no power was the main tank and power was aux. Pretty much a one wire hook up. I think from late 70s on into the 80s they used it.
Just make sure and use a relay for any self engineered system.

[Dragon]

That was the later because there was no gravity feed to the fuel pump. If using a relay use a sealed one as cars can trash open frame relays real fast.

My rear tank had to be jump started to get flow going again as the tank opening is below the valve.

[Dragon]

That was the later because there was no gravity feed to the fuel pump. If using a relay use a sealed one as cars can trash open frame relays real fast.

My rear tank had to be jump started to get flow going again as the tank opening is below the valve.

[willowbilly3]

I don't think gravity flow will affect the valve, the pump sucks the fuel from the tank(s).
I think I would put the relay inside the truck or under the hood, not on the frame

[Dragon]

Ford pumps are not suckers by design all pumps will suck some but the diaphragm is not designed to survive a high suction condition. Close off the fuel line before the pump with the engine running and it can tear the diaphragm.

Experience is a great teacher.

[sideoilerfe]

I've NEVER had a problem with the AUX tanks. Just make sure the lines and valve are clear and you're golden. On my '72, it has a 3 position switch and the middle position is "off" and the others are "Main" and "Aux".

The gauge is controlled by the switch under the steering column and the actual fuel is controlled my the valve on the floor. The floor valve controls the fuel. Just make sure you know which valve position controls what tank and you're golden.