Fitting of twin gas tanks

[Dave M]

Ok, l finally got around to finishing this project. After, sorting out the gas filler for the L/H panel, l fitted up the L/h tank. I bought a new filler tube and filler hose. It was at this point l learnt that the later tanks have a larger filler neck than the '76 tanks. Fortunately the new hose stretched over the larger connection. With the new cap, it now matches the R/H side.
I carefully filed out the hole and fitted the correct year tank selector switch and bezel into the dash panel. Instead of running a fuel selector valve, l opted for another approach. I already had a solid state fuel pump fitted to the existing tank, wired through a pulse relay. I fitted another pump the same for the L/H tank and wired in a changeover relay to select the pump for the corresponding tank.
the new pump and vent lines were simply connected with a tee fitting. The manufacture advised me that the pumps will not allow back flow, so far so good, but l do have a pair of inline check valves in case. The advantage is l now have 2 fuel pumps, should one fail.

You must be registered for see images attach

New selector switch

You must be registered for see images attach

New fuse holders for each pump

You must be registered for see images attach

You must be registered for see images attach

 

[Dave M]

L/h fuel pump fitted to L/H inner chassis rail

You must be registered for see images attach

R/H fuel pump fitted to R/H inner chassis rail, showing tube from left tank tee'd in

You must be registered for see images attach

 

[Dave M]

Relays fitted off on the fresh air inlet bracket. Tucked away yet easily accessible.

You must be registered for see images attach

 

[OldBlueDually]

Relays fitted off on the fresh air inlet bracket. Tucked away yet easily accessible.

You must be registered for see images attach

So do you have a fuel pump on the engine too? Or are you just running the two electric pumps? I am hoping I don't have too big of a task on my hands with my 76 GMC I am doing, but from what I have seen the cobble job under the hood that I just cleaned all up, the tank wiring is my next job to tackle.

You did a very nice job, I like the work and detail you put into this!!

 

[Dave M]

So do you have a fuel pump on the engine too? Or are you just running the two electric pumps? I am hoping I don't have too big of a task on my hands with my 76 GMC I am doing, but from what I have seen the cobble job under the hood that I just cleaned all up, the tank wiring is my next job to tackle.

You did a very nice job, I like the work and detail you put into this!!

No fuel pump on the engine, just the 2 electric pumps. One pump dedicated to each tank.

 

[OldBlueDually]

No fuel pump on the engine, just the 2 electric pumps. One pump dedicated to each tank.

Ok, got it. I was personally thinking of running the stock fuel pump on my Olds 455 that I am putting in this truck, but not running a return or vapor line. I do however want to get the tanks/switch working like it once did.

 

[Dave M]

Ok, got it. I was personally thinking of running the stock fuel pump on my Olds 455 that I am putting in this truck, but not running a return or vapor line. I do however want to get the tanks/switch working like it once did.

Mine is '76 which only had the main supply and a vent tube, which runs to the cannister under the hood. I think you need the vent line and correct cap combination so the tank doesn't build pressure or get vacuum locked.
I still managed to do the pump/tank changeover using the original style switch, and using pump relays to not overload the switch. An advantage of the two pumps, you can flick it over if one pump ***** itself.

 

[OldBlueDually]

Mine is '76 which only had the main supply and a vent tube, which runs to the cannister under the hood. I think you need the vent line and correct cap combination so the tank doesn't build pressure or get vacuum locked.
I still managed to do the pump/tank changeover using the original style switch, and using pump relays to not overload the switch. An advantage of the two pumps, you can flick it over if one pump ***** itself.

Good info, thank you. I will run the vent line then too, I will have to rob it from my parts truck which is why I bought it to begin with!

I did check out the wiring harness too, and the brown wire that was cut under the hood....yup, that baby travels a long distance through that harness! Anyhow, that wire under the hood was also cut near the tank on the passengers side, and the rubber boot connector is still there, and I was able to get a signal through the wire with my ohm meter hooked to the cut wires, and I also hooked it to the switch connection and still received a signal.

I have high hopes the harness is all good because besides the brown wire being cut the remainder of the harness looks to be never touched. I do not know however if the tank solenoid/whatever its called on the frame will work.

 

[DoubleDingo]

Clean installation! I like it!

 

[SquareRoot]

Believe me... you dont want it in the bed fender thing. You dont. Unless you are okay with and understand that you could hinge an access door in that said comparment, but you would want to verify or assure that you ALWAYS have it cleared out around it so that you can put gas in. One way to do so, perhaps, is to make a small tool box over the fender well and maybe keep a spare quart of oil, jumpers, etc and when you open it, have a direct shot down to the fill cap(maybe another door) or you could buy new bedside/replacement panels... eh. New is really only justifyable when you are restoring. They are a pretty penny.

When I said flush mount I meant that old style, but i suppose its not flush with panel in the technical sense. But yeah, I have that style on an old trailer of mine. If I werent considering using it again in future, id offer to cut up... but I might have an old bedside out on my property, i can look to see if it has the kind you seek.

This got complicated quick. Geeez

 

[Kim Burke]

Nice work Dave M. I fussed with mine for the better part of 6 mos.

 

[eskimomann209]

Sorted this problem out ! Thank you to all who offered suggestions, but after a bit of thought, over a few beers, and that is when l do my best creative thinking, l went down this path.
I made up bit of crude tooling with bits and pieces l had in the shed. (refer photo) I shaped 2 MDF pieces to match the curvature of the panel inside and out, hole sawed, (98mm inner and 89mm outer) the 4" pipe piece is used to clamp up the actual panel in between the MDF, with the 3/4" allthread running right through the centre, backed up with 8mm steel plates and 3/4" nuts. This prevents the panel distorting. The stub of 2" pipe keeps the back piece centrered in the 2" hole. Tighten the internal nut and the die presses in!
Also mask off panel prior to starting and do a sample piece before it goes anywhere near the panel. A day to make the tool and 10 minutes to drill and press.
Cracked the paint a bit, but l did expect that. I used a 2" holesaw through the panel, and the hole stretched to 2.5".
I know there are people out there who could make a much more accurate tool with right equipment, but l used what was available to me and l wanted to share this with you,
Dave

You must be registered for see images attach

You must be registered for see images attach

Should make a loan a tool thread and rent that thing out.

 

[eric 87]

DUDE Even with pictures I would need to see it done to figure it out and you did it in your mind.

 

[85 Squarebody76]

Hi all, I'm wanting to fit twin tanks to my '76 Silverado short bed, I managed to get another tank and brackets to do the job, however l need to fit the recess in the L/H panel to mount the filler. I could weld in another section from a donor panel but they are not that easy to obtain here. Was wondering if anybody else has got around this problem with another option,
cheers Dave.

You must be registered for see images attach

I think that some models routed the filler tube into the wheelwell in front of the pass rear tire too

 

[Dave M]

I think that some models routed the filler tube into the wheelwell in front of the pass rear tire too

It's an old thread now, but I managed to sort it with a great result, cheers Dave.