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3rd tank (sub tank ) conversion for a tbi v series truck

camiswelding

camiswelding

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I have a new sub tank that fits nicely between the rails behind my axle on my v3500...(moving the spare inside the bed) I know this has been done before( if you have please answer up so I can have you as a resource) but my question is

what is the correct and sano way to hook the third tank into the dual saddle tank setup....the tbi makes it a little more difficult

1)can I plumb inline with one of the saddle tanks and just use that tanks sender?..

2)will the two pumps work against each other in anyway?

3) Custom bent hardline to rubber pressure line and a "t" ?

Whats the best method?

With the price of fuel its a benefit to buy it where you can get the best price

thanks ck5'ers

cam
 
how much gas do you need? sub tanks are usually 41 gallons or so. my buddy with a crew cab ditched the suicide tanks and went with one sub tank... had to get the frame rail peice off of the old sub to mount it nicely. i dont know what to do with 3 tanks though :-\
 
1.) Add another tank switcher.

2.) A ball valve (return side), two check valves & a tee (pressure side), and some toggle switches (sender, and pump).
 
i would think that you could use a second switch setup and just set one side to your stock inputs and the other to the sub tank, so that switch A would be DS frame tank, and PS frame tank, then switch B would be to switch a, and the sub tank.

i have been contemplating this set up but in a carbed sub, so the switches might be easier to work with...

i just dont know if i want to mount the extra truck tanks in the cabin, as i dont think they'll fit in the stock truck location, but they might fit inside the frame... :dunno:

please post pics of what you end up with i'd love to see a working setup

that 80g AL semi tank i saw keeps looking better and better....
 
I'd use the same 6 port valve and another stock switch. Could put the second valve anywhere in the system, i.e off either existing branch or b4 the current valve.
 
install another tank switch valve between the existing valve and the engine. us the existing toggle between the saddle tanks, and install another toggle switch from saddle tanks to the aux tank. return lines and vapor lines can easily be teed together as they carry no pressure, inlets for the saddle to aux valve would come- one from the aux aux tank, and one from the outlet of the existing valve. doesnt seem like it would be that hard to do. if fuel pump wiring is a problem, install an electric pump between the closest valve to the engine and the engine, and eliminate the in tank pumps altogether, just run one fuel pump rather than 3.
 
Boy... good responses from everyone .. thanks
Ill have to digest your suggestions


1) The saddle tanks are 20 gallons each... the samller sub tank I have is 32... its always nice to have alot of fuel when travelling because of fewer stops and a thirsty BB.... and its also nice to fill where cheaper... gas in cali is now 2.75 to 3.00 a gallon and isnt getting cheaper... diesel is 2.85 to way over three

2) I was interersted in the 6 port setup... what kind of valve would that be... Ive never heard of one

3) I have an addiitonal dual tank switch/lines off my other v3500 so I have the parts to put something together... for sake of ease it seems plumbing the sub tank into one of the saddle tanks would be a way to go because you could basically use the sub pump as a transfer pump to the saddle... this might have problem though because it might overfill the tank...Im not sure
Also if I used the second dual tank switching setup there would be an empty port that would have to be plugged correctly or when switched could suck air and die... (obviously this is fixable)
If I understood what you were saying correctly you were suggesting putting a second dual tank switch into the cab.... or figure out a 3 way switch... again it seems plumbing into an existing saddle if possible would be the easiest... and sano way to go

3) Putting tanks in cab is not an option... for safety.. for room.. for smell .. in cab tanks might be ok on a trugie but not a tow rig

This is all going to happen when I pull the dually bed for a custom flatbed Im building from aluminum.... and tank access is easy...

Please keep the suggestions coming

cam
 
I think the easiest way would be to replumb the existing setup first.

1) Rig it to use the factory tank switching to select either 1 saddle tank or the Sub tank.

2) Rig the 2nd saddle tank with a transfer pump into the Sub tank. Now when you flip on the transfer pump, the 20 gallon saddle tank can't overfill the 32 gallon tank. :cool1: (At least if ya wait until the 32 gallon tank is mostly empty before ya flip the switch!) ;)
 
The 6 port valve is the OE valve used in vehicles with fuel return systems.

I'm very leery of transfer tank systems. The potential for dripping fuel on the road or starting a vehicle fire is large. Adding in another 6 port valve and stock tank selector switch negates the need for a pump and a brain not functioning on White-Line Fever.
 
agreed, the 6 port valve should be stock, and should go into 3 separate lines. each tank has its own feed line, a vapor line, and a return line. by installing the new valve in between the existing valve and the engine, you eliminate a lot of extra wiring and hose routing. the only thing you'll need to add woudl be the lines running from that valve to the sub tank, and power for the pump and guage sender. shouldn't be a big deal at all that way.
 
agreed, the 6 port valve should be stock, and should go into 3 separate lines. each tank has its own feed line, a vapor line, and a return line. by installing the new valve in between the existing valve and the engine, you eliminate a lot of extra wiring and hose routing. the only thing you'll need to add woudl be the lines running from that valve to the sub tank, and power for the pump and guage sender. shouldn't be a big deal at all that way.
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agreed, the 6 port valve should be stock, and should go into 3 separate lines. each tank has its own feed line, a vapor line, and a return line. by installing the new valve in between the existing valve and the engine, you eliminate a lot of extra wiring and hose routing. the only thing you'll need to add woudl be the lines running from that valve to the sub tank, and power for the pump and guage sender. shouldn't be a big deal at all that way.
 
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