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Old 03-28-2016, 11:39 AM   #8
foamypirate
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Join Date: Apr 2009
Location: Pflugerville, TX
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Re: Ls swap dual tank, fuel system parts list, for return rail system???

Quote:
Originally Posted by izzy_Britton View Post
Sorry to revive an old thread but i too have had some questions on this and i am not able to get hard definitive answers. I am going to go ahead and give my thoughts and theories here and maybe someone can straighten us all out.

This is my plan:

87 tanks

87-91 sending units with pumps attached (pumps replaced for higher flow versions maybe).

87-up fuel tank selector valve (under the cab not the dash mounted button)

03 corvette fuel filter with built in pressure regulator


so basically (i think) it goes like this:

(basic operation) The in-tank fuel pump with pump fuel from the tank, thru the tank selector switch, to the usual connection on the switch. then the fuel will continue to the 'vette filter regulator, then on to the engine.

Seems logical so far.

The 'vette filter regulator will return fuel back to the switch mech. and the switch mech. will return the fuel back to the proper tank.

plumb the 'other' tank exactly as the first with the lines inserted into the 2nd tanks ports on the tank selector switch.

so in the above scenario using the OE/replacement 87-up parts and placing the 'vette filter regulator combo device between the fuel tank selector valve and the engine, everything SHOULD work as it was originaly designed to work. the return line from the vette filter regulator would simply return fuel back to the tank selector valve exactly as it would have on a stock carb'd or TBI setup.

Anyone with experience in this matter see any fault with this set up?


Assuming the above is correct, the only real conundrum that i am having is the wiring portion. On the 87-up trucks, the trucks are wired for in tank pumps, changing sending units and pumps should be a plug and play situation. My truck is a pre-tbi so therefor my truck is not wired for electric in tank pumps. so i have no idea how the pumps are wired nor how the dash switch is wired for the pumps to kick on.

I would also assume that the pump that is in the non-selected tank is not running?

anybody?

thanks in advance.

-Izzy
This is the exact setup I have in my truck, works great. You are correct in that only the selected tank's pump will run.

You have a few options for your wiring:

1) Find the dual tank wiring harness from a TBI truck that is in good shape.

2) Build your own harness following the factory wiring diagrams.

3) Build your own harness with relays powered by the TBI tank switch. This is more complicated, but also bomb proof if done right, and you'll get a better power supply to your pumps.


It's a pretty simple harness, I'll see if I can't find you the factory wiring diagrams.
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