I have a 90 gal RDS transfer tank in my Dodge that was gravity feed. DOT in Cheyenne, Wy wrote me up for operating with an illegally modified fuel system. If the tag on the tank specifies 'Transfer' then a pump must be used to transfer fuel from aux.tank into main fuel system. My tank has a suction straw on top, so I installed a 5/16 hose barb into the fitting, then mounted a Mr. Gasket electric fuel pump to the inside of the truck bed. I connected the fuel line from the fuel tank outlet to the inlet side of the pump, then tied the discharge line into the vent line on the filler neck. 100% legal, and 1 wire to a switch is all you need. When the fuel level drops on the lower tank, I turn on the pump for about 30 seconds to start the fuel flow, then siphon takes over, and I turn the pump off. As the fuel is used from the bottom tank, fuel is siphoned from the top tank. The fuel gauge never moves until the aux tank is empty, and normally I never have to turn the pump on again until I refuel again. When the gauge does begin to move, I still have a few hundred miles to get fuel. Total cost of fuel transfer system was less than $50. DOT explained to me that a transfer tank must have some type of transfer pump installed to pump fuel into the main fuel system. If a pump is not used, then the tank ID tag must specify 'fuel tank'.

 

Don't forget to have the fuel from the aux tank run through a filter. When I worked at the local dealership, our service department had to deny warranty to a lot of guys who were running aux tanks without filters. Very often we would pull the injectors due to a no start condition and see them plugged with iron filings. Same as lift and injection pumps, littered with iron filings. Sad to see so many people have to buy a 4000 dollar injection pump rather than a 13 dollar filter. Even if it was a plastic aux tank i would still filter it.

 

All under the front left corner of the bed. My aux. fuel tank drain is near the front left corner of the tank. I plumbed it back ~4" through a manual 1/4 turn valve, then down through the bed, left through the filter housing / filter, electric valve, down to Carter fuel pump, then across to vent line to fill OEM tank. Valve opens and pump starts all on the same switch. Here's my set-up:

 

Thanks everyone for the help. The problem I'm having on mine is this; it is not flowing fast enough into the main tank...it takes to long to fill up. I guess the only thing I can do is find a bigger valve to let it flow more fuel. What electric valve are you all using? I'm currently using a pollack 3 way valve...the kind that Ford used on the dual tank trucks.


Thanks, Tony

 

Take a look at.

http://www.northerntool.com/webapp/w...5501_200315501

Mike

 

I just use a cheap one I found in the hydraulic section at Princess Auto. Bought two and have a spare in case. With the pump it fills plent fast enough - especially if you forget to watch the fuel gauge as you're driving.