Dual Fuel Tank Switchover Valve

[vwnate1]

O.K. I scored one of these with the attendant plumbing and hoses , MPC plug and a foot or so of the harness , anyone know how it's wired ? my factory shop manual doesn't mention it .

I allready have the dual fuel tanks and I'd like to get them working again .

TIA ,

 

[nerfherder78]

What year is the valve from?

I have most of a harness from an '85 that I'm going to use in my truck, but I still need to find out which pink wire goes to the cab and which pink wire goes to the driver's side tank.

 

[vwnate1]

Tank Wiring

Well ;

The right side gauge's wire is _tan_ as is the bulkhead to switch wire from the gauge head .

The switch fits from 1974 ~ 1987 ,maybe more years , I have the Delco P/N for it stashed @ work if you need it .

I have _one_ loose pink wire with the fuel tank connector on it I picked up from one of my Pick-A-Part runs , I don't know but I'm guessing it's the secondary tanks tank gauge to switchover valve lead .

Thanks for taking the time to read & respond , last night I dismounted & drained the stock right side saddle tank , it had flakes of bad rust in the brown liguid inside and the pickup tube and float arm were both rusted clean off .

Interestingly , the pickup's intake screen appears to be O.K. *if* I can clean all the rust chips out of it .

I'll measure the tank to-morrow and go try to match it up .

As this truck now has two fuel gauges on the dashboard , I'm considering using one for each tank .

 

[nerfherder78]

Found this while looking for the answer to my wiring: http://coloradok5.com/forums/showthread.php?t=136836&highlight=dual+tank+wiring. Hopefully that helps with your wiring, mine appears to be different.

This is how the switch/valve were wired in the truck I pulled them from:

 

[vwnate1]

Thankyou !

Both the diagram and linked post are *very* helpful ! .

I didn't take the time to trace the sub harness so I have the pigtail with 2' of harness , maybe I'll go back and get another sub harness as these factory dual tank setups are very common .

My truck , has some aftermarket thing - I don't want to saw a rectangular hole in my dash but I can get a bat handle DP , DT toggle switch to match the gone
missing one .

See how easy it is to be helpful guys ? I KNOW you're lurking out there , reading this and knowing the answers .

I'm a Mechanic , not a Computer savvy person so I'da never found that link .

 

[nerfherder78]

I finally got the time this past week to work on my truck and installed the second fuel tank and valve. Spent part of yesterday and most of the day today trying to purge the air out of my fuel system. For some reason it was only sucking up air, which killed my lift pump. Just one of those projects where everything that could've gone wrong, did. Even my computer got in on the act, so after i finish buttoning up my truck tomorrow I need to see about buying a new video card. At least now my truck is happily clacking away again.

As for the wiring from the '85, the pink wire leading to the fuse box is an ignition hot. The two green wires alternate 12V based on the position of the switch. The solid pink wire is the signal from the gauge, and the pink/white wire is the driver's side tank.

Adding the factory switch to the dash was one of the easier parts of this project. After some careful measuring, I used a 7/8" hole saw to cut a hole in the dash, then used a file to expand the hole to the proper dimensions (~1.7"x1"). I cut it small and had to expand it just a bit to allow the switch to function without interference.

 

[vwnate1]

Dual Tank Fun

Thank you for the update ~

As it turns , my dual tank setup is an aftermarket one by " Travel Tanks " and so it uses a DPDT bat handle switch , I was able to find one with the correct screws and knurled dash nut and installed it , it is designed to use the stock dash gauge for both tanks and switch the tank feed wire over at tghe same time it flips the fuel valve .

I was able to find and original GM dual tank valve , up to '77 or so , it only has hose ports and one wire , makes things simpler .

As the DOPO had pried the auxilliary tank's cap off and ruined the filler neck , I hunted up another original GM pre - smog filler neck and welded it to the tube , as soon as this heat breaks (113° yesterday) I'll install it and both tanks will be functional .

I'm still not done with the dahsboar yet , - it's buggered beyond belief - I'vebeen collecting bits & bobs down @ Pick-A-Part and will build a stock dash pod from parts , dumping the (stupid , didn't work when new) Ammeter for a proper Volimiter and maybe a nice factory clock too .

I finally got my N.O.S. AC - DELCO matching key dual tank locking filler caps in yesterday so that's nice . I've been waiting for them to arrive from Wast Grunt , Mn. for a month or two now , pins & needles .

Meanwhilst the old truck is running sweetly as a proper Farm/Ranch/Work Truck is wont to do , the old InLine 6 Banger purring over hill and dale , never a hiccup .

I found a junked one with factory AC complete & good and had to run away before stripping it all out for my rig , I don't need it really .

 

[nerfherder78]

So you're using one more like the one in this picture? I pulled this one off my brother's '78 C20 along with the 2nd fuel tank before it went off to the junkyard. Unfortunately, I was busy that weekend and didn't get the switch (23-275/23-276) or any of the wiring, which is why I ended up buying the setup off the '85.

 

[vwnate1]

Electctro - Valve

Sort of ~ that's the non SMOG version , it's made my Pollack (a very good quality item) , the one I used has this one wire but has 6 ports as it also has to switch over the vapor recovery hoses .

I now have one valve like this and another , far more complicated one with multiple wires to switch the gauge feeds over too , I no longer need them and will hang onto them until someone needs then or they get tossed out in a fit of pique .