Adding second fuel tank

[Matt S]

I'm thinking of adding the passenger fuel tank. I have an extra one lying around. Instead of adding all the factory splits and valve, I was thinking of trying to use the passenger tank to fill the driver tank. This way only one feed to the engine. Has anyone done this sort of thing and have any thoughts or pictures?

My current M1031 has no bed on it yet.

 

[M813rc]

I did that on my M1028A2. It was easier than trying to add a factory-type twin tank setup with extra valves, fuel return lines, etc.

There is a simple one-way 30gph pump, with a switch on the dash, to send the fuel from the passenger side tank to the drivers side.
The auxiliary tank has a fuel level sensor, attached to a relay and a momentary switch on the dash, so you can monitor fuel level in both tanks on the truck's main gauge. Unless the switch is pushed, the gauge shows the main tank level.

30gph may sound slow, but it will refill the main tank much faster than you can burn the fuel while driving.

Cheers

 

[antennaclimber]

I have added the passenger side tank to 2 trucks.
Added an electric pump to transfer fuel from the passenger side to the drivers side. The pump is mounted between the tanks on the frame cross member.
Also added a second fuel gauge to monitor the right side fuel level.
We kept the factory fuel supply and return lines intact to the drivers side.
The electric pump is on a Momentary switch to help prevent the possibility of over filling the drivers side.

Cut a hole in the side to accommodate the fuel filler neck.

Attached are a couple of pictures.

 

[Matt S]

I have added the passenger side tank to 2 trucks.
Added an electric pump to transfer fuel from the passenger side to the drivers side. The pump is mounted between the tanks on the frame cross member.
Also added a second fuel gauge to monitor the right side fuel level.
We kept the factory fuel supply and return lines intact to the drivers side.
The electric pump is on a Momentary switch to help prevent the possibility of over filling the drivers side.

Cut a hole in the side to accommodate the fuel filler neck.

Attached are a couple of pictures.

Thanks for both responses.

This is what I'm looking to do. It appears you have a 3 outlet sending unit on the new tank with 2 outlets blocked off. Do you plumb the feed from the new tank into the breather of the original tank? What is a momentary switch? I was was thinking using an existing switch in the truck. My 1031 came with a light on top of the box with a switch and a lite when on in the cab. Filling it when the other gets down. I hadn't thought of a gauge and I'll have to figure that out so I don't burn out the transfer pump.

 

[M813rc]

A momentary switch is one that has to be pushed to work, once you release finger pressure on it, the switch turns off.

In the case of mine for my gauge, when I push the switch, the gauge shows the fuel quantity in the auxiliary tank. As soon as I release the switch, it reverts back to indicating for the main tank.

Antennaclimber and I did essentially the same thing. The only difference is I have an "on" switch for the pump, rather than a momentary, and you need to watch the gauge to prevent overfilling.
The switch is wired so that the pump is only powered when the key is on. This is so I cannot walk off from the truck and accidentally leave the pump transferring fuel. Not that I'd ever do something like that....

Cheers

 

[antennaclimber]

Hi Matt,
Yes I did use the 3 outlet sending unit for the new tank.
One port was used to go to the fuel pump.
One port was connected to the unused port of the factory tank.
Last port was capped off.

The sending unit is a 90 ohm resistor, so I used a fuel gauge from Summit: Fuel Gauge

Like Rory states, the switch will only run the pump while you have it depressed. This way, the pump will not overfill the stock tank if you forget to turn the pump off. I did that in my garage during testing, so I highly recommend that you use a momentary switch.

His idea of showing the fuel level as well is really a good idea. I had a custom console made up and added a second fuel gauge.

My idea of a 2nd tank was to safely carry 20 more gallons of fuel without the need to mount fuel cans and the need to stop and dump them in. (Sometimes fuel cans have a way of disappearing if they are not secured.) This way, I can "refuel" while driving down the road.

The only down fall has been at the fuel pumps. You will need to turn the truck around to fill both sides. Truck stops have pumps on both sides, but I prefer to stay away from those pumps. They are not friendly places.

Karl