Adding fuel tank on cucv m1028

[tommi3520]

Hi

I have 1986 cucv m1028, and im going to add antoher fuel tank on the passenger side, the parts that i have oredered are:

-The tank
-Hardware to mount it to the frame
-Fuel hole in bed (cut from donor truck, welded to my bed), fuel filler neck and everything to put fuel in the tank from the passenger side.
-Spectra premium fuel tank sending units FG05L
-GM Genuine Parts D7003 Fuel Tank Selector Switch
-ACDelco U7001 Professional fuel tank selector valve
-WVE by NTK 1P1132 fuel tank selector valve connector, 1 pack

The original fuel sender on drivers side has 3 ports on fuel sender, so i ordered fuel sender on passenger side with 3 ports, hope that works.

So my question is how to plumb both tanks to the fuel selector valve and the how to wire the fuel tank switch in dash to the fuel selector valve connector. I tried to order as many oem parts as i could so i would not have to invent the wheel all over again, so hopefully i can get straightforward diagrams or something along those lines.

 

[WWRD99]

Hi

I have 1986 cucv m1028, and im going to add antoher fuel tank on the passenger side, the parts that i have oredered are:

-The tank
-Hardware to mount it to the frame
-Fuel hole in bed (cut from donor truck, welded to my bed), fuel filler neck and everything to put fuel in the tank from the passenger side.
-Spectra premium fuel tank sending units FG05L
-GM Genuine Parts D7003 Fuel Tank Selector Switch
-ACDelco U7001 Professional fuel tank selector valve
-WVE by NTK 1P1132 fuel tank selector valve connector, 1 pack

The original fuel sender on drivers side has 3 ports on fuel sender, so i ordered fuel sender on passenger side with 3 ports, hope that works.

So my question is how to plumb both tanks to the fuel selector valve and the how to wire the fuel tank switch in dash to the fuel selector valve connector. I tried to order as many oem parts as i could so i would not have to invent the wheel all over again, so hopefully i can get straightforward diagrams or something along those lines.

I think the fuel valve has a feed and return line for each tank so that's pretty simple...the wiring from the switch is a little more challenging if you want the fuel gauge to indicate for each tank...if you just do one tank for the gauge it would be very simple...from the switch to the valve.

 

[nyoffroad]

Well I was going to say go to the local junkyard and find a doner truck, but the I saw your in ICELAND! So much for that idea. I think your going to have to do a lot of research online for the wiring and fuel routing. sorry I'm no help.

 

[tommi3520]

WWRD99 i should have mentioned that i will have a separate fuel gauge for my extra passenger tank.

nyoffroad why do i need a donor truck?, having all the parts, do you mean to see the routing and wiring?

My question is the wiring and fuel hose routing, see picture, this came oem in some trucks from factory, so this should not be rocket science to plumb and wire up, problem is that it comes with no instructions only "wire it up the same as before" like if i was working on a truck with dual tanks from factory. Tomas

 

[WWRD99]

WWRD99 i should have mentioned that i will have a separate fuel gauge for my extra passenger tank.

nyoffroad why do i need a donor truck?, having all the parts, do you mean to see the routing and wiring?

My question is the wiring and fuel hose routing, see picture, this came oem in some trucks from factory, so this should not be rocket science to plumb and wire up, problem is that it comes with no instructions only "wire it up the same as before" like if i was working on a truck with dual tanks from factory. Tomas

View attachment 887920

ok having a guage for each does make it easier to do! as far as what wire goes to what not sure. I think I see 6 wires on the plug to the fuel transfer switch...I'd have to go on a site for non cucv wiring for gm and find the schematic. I think there's a site called classic wiring?? might have that diagram.

 

[tommi3520]

ok having a guage for each does make it easier to do! as far as what wire goes to what not sure. I think I see 6 wires on the plug to the fuel transfer switch...I'd have to go on a site for non cucv wiring for gm and find the schematic. I think there's a site called classic wiring?? might have that diagram.

Yes the plug, plugs right in the fuel selector. the wires from the plug to the switch is what i need to know how to wire

 

[nyoffroad]

A doner truck could be a source of the wiring harness for the switch and gauge. From the pic you seem to have just the end.

 

[tommi3520]

yes i see, if i just know which wire go to which connectors on the switch, then i can do the rest, with the gauge, i dont think ill run into any problems. its a new gauge from autometer that ill be using with the extra tank and comes with wiring diagram, and on the sending unit side, it should be straight forward

 

[Sharecropper]

Here - see if this helps. Now let me go back to sleep.

 

[nyoffroad]

Here - see if this helps. Now let me go back to sleep.

NICE! Now go back to sleep , grouch.

 

[tommi3520]

thanks for all the info, i think i might just use a pump between tanks and call it good., I will now start to look at which ports on the senders i can use to pump fuel from the aux tank to the main tank. Both senders have 3 ports, i see on my main tank that one is for fuel pump in engine bay, one for return line and one capped off, i might be able to use that one to receive fuel from the aux tank.

 

[nyoffroad]

You could tap into the top of the metal filler neck and braze or weld a fitting in there, after removing it of course!
That way the fuel just runs down into the tank from the highest point, the pump should stop any siphon effect and if you use a momentary type of push button switch you don't have to worry about forgetting the pump on.

 

[Sharecropper]

Guys, the easiest thing to do is simply to install a diverter valve in the floor between the tanks to select which tank the fuel pump sucks from. I've already done this and wouldn't have it any other way. There are three outlets on the tank - the largest (3/8") on one side is the suction, the middle is a vent that is not used, and the other (5/16") on the opposite side is the return from the engine. https://www.steelsoldiers.com/threads/kinda-got-carried-away-m1028-rebuild.54469/post-2426941

 

[Winston Wolf]

Did you get it done? I added a 2nd tank years back. I used an OEM style switching valve in the stock frame location. The switching valve also contains the electrical switch to tell the sender which tank is being used, so there is only the stock 1 wire that goes to the fuel gauge. My setup is identical to the way the factory did it, and it works perfect, no need for a 2nd fuel gauge, just flick the switch quick if you need to check the other tank's level.

 

[tommi3520]

I ended up just putting a pump between the tanks. the fuel selector thing was to complicated and no good info to find.