Fuel Tank

[pilotXC]

As I start my swap, I'm wondering is there any reason why no one uses the mid 90's side mount gas tanks? Do they not fit in the older style trucks? I don't like the rear mount tank hanging down and don't want a bed fill either, so curious why no on seems to do side mounted tanks as GM did/does on trucks?

[ls1nova71]

Not sure what year truck you have, but unless it's an auxiliary tank, they dont fit on a 67-72 and auxiliary tanks are kind of small.

[sweetk30]

x2 on a LOT more info of your vehicle required .

88-up new body trucks went inboard of frame and the frame bows out the further back it goes after the cab so there not a easy fit at all .

if square body 73-87 then just get a 1987 tank for short or long bed for factory tbi injection . then a tbi sender unit minus pump . then a acdelco ep381 pump from a 1996 c3500 5.7L is a direct swap and has the psi and flow to get you started on the efi swap . or ask the place your getting efi from what pump they recommend to plug-n-play on the gm sender .

make sure you read and search a lot on efi there is good kits and bad kits . look real hard at the options and price points . learn from others troubles and try not to have the same happen to you . see my sig line below .

[pilotXC]

Thanks for the replies. The stock tank behind the seat isn't very big either, they are 16 or 17 gallons I believe, there is not a good option really for fuel tanks on the 67-72 trucks, in my opinion.

Mine is 72 K20, I'm installing an LQ4/4L80E and since I'm going to have to modify the stock tank behind the seat to work with EFI, I'm just trying to find the best possible solution that I like. I also have the dealer installed saddle tanks with the aluminum filler flaps. I'm good with the saddle tanks, and actually prefer them over the other options, but hate the aluminum filler flaps. But not sure how easy it would be to have 2 tanks with EFI... I assume using the 1987 control module would work and I could install separate internal pumps on both tanks?

[sweetk30]

i kept my truck stupid easy for me on efi and 2 tanks . driver side has high psi pump for efi and pass side has low psi tbi pump . i modified the wiring on the dash switch to just send power to the right tank pump when flipped right . i added a red light for when the pump is on to not forget and over fill . also the pump only gets power key hot so this is another safety . this seems to work good for me and no problems .

if you dont plan a ton of driving and high fuel use loads the 17-18 gal range tank will prob be good for you . i run my 20 gal tank for most of my driving . around town few towns over and no major drinking of fuel .

dont forget the in cab tank was never designed for return fuel flow so you might get unwanted fuel smell .

[pilotXC]

I"m confused on how to make 2 tanks work with the stock '72 gas gauge. I've read the threads here:

http://67-72chevytrucks.com/vboard/s...d.php?t=379708

http://67-72chevytrucks.com/vboard/s...d.php?t=674371

I'm still not sure how this would work or not on a '72. Sounds like most of the comments are around sq body trucks and using the '87 plumbing and selector, would the same set up work in a '72 without '87 tanks? So long as I had 60psi rated pumps in both tanks? How would the wiring harness tie in from the LQ4? Or would I wire in the existing fuel gauge to the harness somehow? Thanks for the help here, just trying to figure this all out...

[Captainfab]

Just to clarify. You are using the TBI pump in the passenger side tank to transfer fuel to the drivers side tank when needed? And the engine is fed fuel from the drivers side tank only?

Originally Posted by sweetk30

i kept my truck stupid easy for me on efi and 2 tanks . driver side has high psi pump for efi and pass side has low psi tbi pump . i modified the wiring on the dash switch to just send power to the right tank pump when flipped right . i added a red light for when the pump is on to not forget and over fill . also the pump only gets power key hot so this is another safety . this seems to work good for me and no problems .

if you dont plan a ton of driving and high fuel use loads the 17-18 gal range tank will prob be good for you . i run my 20 gal tank for most of my driving . around town few towns over and no major drinking of fuel .

dont forget the in cab tank was never designed for return fuel flow so you might get unwanted fuel smell .

[pilotXC]

I haven't done anything yet and would prefer to have both tanks operate separately with the in cab switch, but not sure if that's possible by modifying the tanks I have or not.

[sweetk30]

Originally Posted by Captainfab

Just to clarify. You are using the TBI pump in the passenger side tank to transfer fuel to the drivers side tank when needed? And the engine is fed fuel from the drivers side tank only?

100% yes correct . my pass side tank is basicly a bolted on jerry can .

[sweetk30]

Originally Posted by pilotXC

I haven't done anything yet and would prefer to have both tanks operate separately with the in cab switch, but not sure if that's possible by modifying the tanks I have or not.

in todays market of custom parts why not make up a cardboard or thin wood tank as bai as you can fit under the cab and bed like a 73-87 style and have it made for you and have it setup to use a common late model efi sender for the fuel pump unit .

or maybe even see just how easy it might be to use a 73-87 style tank under there and just get one for a 1987 tbi spec truck and sender minus the pump and use the later acdelco ep381 pump . then if you dont like the gas doors on the box like you said graft in some from a newer vehicle and make them blend in nice . maybe 88-98 style for the round yet flush door for fuel .

[Captainfab]

Yes you can feed the engine from either tank if you want, but you will need two of the new higher pressure pumps instead of just one. The issue with using the tanks that you already have is finding someone willing to cut, weld and modify fuel tanks that have already has gas in them. It can be done, but most welders prefer not to, including me. It might not be much more expensive to just have someone duplicate the tanks that you have but design them for EFI at that time. The one plus is that you will have brand new, perfectly clean tanks.

Originally Posted by pilotXC

I haven't done anything yet and would prefer to have both tanks operate separately with the in cab switch, but not sure if that's possible by modifying the tanks I have or not.

[pilotXC]

Got it, thanks for the reply on the fab work. The shapes of the tanks are pretty basic, so you might be right on having them remade...

Does anyone know if using what would have been stock fuel pump from a 2001 GM in two tanks can be wired to the harness? Is that what someone on here sells? I saw a bit on the show Trucks where they used the 2001 fuel pump and used the stock sender blocking off the fuel pump pickup so the original dash gauge would work and curious if you could wire that up to work for 2 tanks?

[Captainfab]

You're going to need a dual tank switch similar to what is used in the '87 trucks.

[pilotXC]

Right, so if I used two 2001 electronic fuel pumps with the 6 port tank selector from an '87 rated for 65 psi, and main/aux switch in the cab, and '72 sending units for the gauge, in theory that would work right?

[Captainfab]

Yes I believe that should work.