Dual gas tank set-up idea.

[T-roy K10]

The truck is an 85 K10 with a carb’d 350 and dual tanks. the previous owner did a frame off resto on it and everything is new, but doesn’t work very well. I can use a little more than half a tank before it runs out and have to switch over. The gauge reads pretty close to what’s actually in the tanks when they seem to run out. Obviously there is a problem with the valve OR the routing of the system/ valve. It also has an external electric pump with return line back to the tanks. The return line branches off the fuel filter. I installed a pressure gauge and amazingly it has right at 5lbs of pressure even though there is no regulator.
anyway, here is my idea. (We do this with auxiliary tanks on jet skis) pull from tank one with the pump. Cap the tank 1 return line. Pipe the tank 1 vent over to the tank 2 pick-up and run the tank 2 vent to the usual. The return line will go to tank 2. So, as the fuel is pulled from tank 1 the vacuum will pull the fuel from tank 2. Tank 1 stays full until tank 2 is empty. This works great as long as the tank 1 cap is sealed, which mine has an o-ring. The only issue with this would be if air can seep into tank 1, OR the electric pump isnt able to pull through that much line. Shouldn’t be any worse than running 1 tank dry as long as you don’t run tank 1 dry Then you would be lifting from 2 tanks at the same time.

anyone hear of someone trying this before ?

 

[75gmck25]

Makes we wonder how they did a frame off “restoration” but didn’t get the fuel right.
Your scheme might work, but why jury-rig and re-invent the wheel.
- Get one tank working properly with your pump and a return line and make sure it draws down the tank to near empty. Pump should be mounted near the tank and as low as possible.
- then look at the wiring diagram for a new six port fuel switch/solenoid and run the wiring and fuel lines. Move your electric pump so it is after the solenoid, but still as far back as possible.

 

[Scott91370]

Makes we wonder how they did a frame off “restoration” but didn’t get the fuel right.

It happens... Problem for me was after it got put back together for paint the interior was still all apart so I couldn't test the gauges. Not I have a guage that reads empty and no desire to pull things apart to make it work right.

 

[T-roy K10]

Makes we wonder how they did a frame off “restoration” but didn’t get the fuel right.
Your scheme might work, but why jury-rig and re-invent the wheel.
- Get one tank working properly with your pump and a return line and make sure it draws down the tank to near empty. Pump should be mounted near the tank and as low as possible.
- then look at the wiring diagram for a new six port fuel switch/solenoid and run the wiring and fuel lines. Move your electric pump so it is after the solenoid, but still as far back as possible.

why? I’m thinking that it would be less parts and that equals less issues down the road. AND less research/work to get it working correctly.
it seems to me that problems with these systems are common… no?
this doesn’t make sense to me either because he did a crazy amount of work to just say f it on some issues like this. I guess he just got tired towards the end.

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[75gmck25]

The stock dual tank setup is not that complicated. However, it uses a lot of rubber hoses, which have deteriorated from ethanol fuel, and the older 6 port valves are no longer sold anywhere.

I still have a working older 6 port valve (with a single power lead), and I’m lucky that it works. This makes my electrical setup fairly simple, even though there are a lot of long wires. However, by my count there are three hoses on each sending unit, six hoses connected to the solenoid, and three more hoses in the engine compartment - a lot of rubber hoses to crack, deteriorate and fail. I have replaced them all with EFI rated hose, so I hope they are now reliable.

If you want a really simple setup, install a Suburban 25 gallon or 40 gallon tank in the back where the spare tire goes, and forget about dual tanks.

 

[T-roy K10]

The stock dual tank setup is not that complicated. However, it uses a lot of rubber hoses, which have deteriorated from ethanol fuel, and the older 6 port valves are no longer sold anywhere.

I still have a working older 6 port valve (with a single power lead), and I’m lucky that it works. This makes my electrical setup fairly simple, even though there are a lot of long wires. However, by my count there are three hoses on each sending unit, six hoses connected to the solenoid, and three more hoses in the engine compartment - a lot of rubber hoses to crack, deteriorate and fail. I have replaced them all with EFI rated hose, so I hope they are now reliable.

If you want a really simple setup, install a Suburban 25 gallon or 40 gallon tank in the back where the spare tire goes, and forget about dual tanks.

In case I decide to back oem. Isn’t this the correct valve?

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[Old77]

In case I decide to back oem. Isn’t this the correct valve?

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Yes, or get this from Rock Auto for cheaper and probably better quality. No telling what brand LMC is selling....

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[SquareRoot]

"It sounded like a good idea at the time"

 

[75gmck25]

For your year truck, that should be the right valve.

The issue I have is that my ‘75 has an older 6 port valve that is no longer available. If I swap in a newer design 6 port valve I have to do quite a bit of rewiring, and I probably need a new dash switch. However, so far my old valve is still working fine.

 

[Ricko1966]

If I understand correctly you are running out at 1/2 tank and you still have 1/2 tank when you run out. If that is the case it sounds like you have the wrong sender,the pickup tube on it isn't long enough. Possibly a TBI sending unit with no pump on it. If it works fine until 1/2 tank I don't see how it can be a tank valve.

 

[T-roy K10]

If I understand correctly you are running out at 1/2 tank and you still have 1/2 tank when you run out. If that is the case it sounds like you have the wrong sender,the pickup tube on it isn't long enough. Possibly a TBI sending unit with no pump on it. If it works fine until 1/2 tank I don't see how it can be a tank valve.

Possibly. but I won’t know until I pull the bed and investigate.
actually one went down to about a quarter and the other to about a half. Yeah it’s a big cluster.