tank switch/valve

[Rip]

I have a '80 Silverado Stepside Big 10 with a 350 4 bbl and TH350. It has duel tanks with mechanical pump. The tank valve is the type with one light green wire to it from the switch. Also coming from the switch is a red, pink with white stripe, blue, land dark green wire. The dark green wire goes to a connector that attaches to the side of the fuse block. It has other wires that go different place but nothing is plugged into this connector. My first question is what plugs into this connector? I think the red wire actually comes from the fuse block and runs down the passenger frame rail around back up the driver side rail the the switch. Is that correct? The blue wire goes to the driver side tank and the pink with white goes to the passenger side tank. Those are for sending units? At the switch, with it flipped down to the left tank position, with a test light i have power on the red wire with the key on run. The blue wire is hot at this time also. The gauge shows past full. When i swtch the selector to the right tank, the gauge shows empty(which it is), and the red wire goes dead as well as the blue. Question 2 is shouldnt the red wire stay hot and the blue and pink with white alternate with the switch being flipped? Question 3 is shouldnt the light green going the valve get hot at some point to activate the valve? I changed the switch but it made no difference. Any help would be appreiciated.

[Rip]

The grounds coming from the tanks were checked and they seem good, im wondering now which on feeds the gauge? I checked old posts and most deal with 5 wires on the valve or for 85 or 87 trucks. There are there are suction and return lines going from the valve to the pump and the same lines going to each tank. 

[81_Chevy]

these might help: http://forum.73-87chevytrucks.com/smforum/index.php/topic,11766.0.html

oh and Welcome to the Forums!

[Rip]

It helped some but not totally. Im gonna try to look in the tech pages again. Thanks though!

[bd]

I have a '80 Silverado Stepside Big 10 with a 350 4 bbl and TH350. It has duel tanks with mechanical pump. The tank valve is the type with one light green wire to it from the switch. Also coming from the switch is a red, pink with white stripe, blue, land dark green wire. The dark green wire goes to a connector that attaches to the side of the fuse block. It has other wires that go different place but nothing is plugged into this connector. My first question is what plugs into this connector? I think the red wire actually comes from the fuse block and runs down the passenger frame rail around back up the driver side rail the the switch. Is that correct? The blue wire goes to the driver side tank and the pink with white goes to the passenger side tank. Those are for sending units? At the switch, with it flipped down to the left tank position, with a test light i have power on the red wire with the key on run. The blue wire is hot at this time also. The gauge shows past full. When i switch the selector to the right tank, the gauge shows empty(which it is), and the red wire goes dead as well as the blue. Question 2 is shouldnt the red wire stay hot and the blue and pink with white alternate with the switch being flipped? Question 3 is shouldnt the light green going the valve get hot at some point to activate the valve? I changed the switch but it made no difference. Any help would be appreciated.

For the subsequent discussion, locate the "Auxiliary Fuel Tank" wiring on page 11 of this wiring diagram.

You should see five wires connecting to the tank selector switch:  (1) pink/black (ignition source from fuse box), (2) light green (to tank selector valve), (3) pink (becoming tan as it passes thru the 4-wire firewall connector, loops down the left frame rail then back up the right frame rail and into the cab to the fuel gauge), (4) light blue (to left tank sender), and (5) pink/white (becoming tan/white between the 4-wire firewall connector and right tank sender).

It sounds as though the selector switch isn't connected to Ignition at the fuse box - perhaps a blown fuse, or the wire is unplugged.  Ignition connects to the dash switch solely to energize the tank selector valve - it has no electrical connection with or bearing on fuel gauge function.  The 'dark green' wire you observed at the fuse box may actually substitute for the 'pink/black' wire in the wiring diagram.  Study the diagram carefully and compare it to your switch wiring to puzzle it out.

The power you're registering with your test light on the light blue wire is actually coming through the fuel gauge.  The gauge is powered directly by ignition.  The tank sending units are variable ground connections that modulate the gauge.

Once you've pondered this information for a bit, if you have more questions post them.  And, let us know how it turns out.

[Rip]

It seems it goes back to my first question. What might plug into the connector that the green wire goes to? There is a pink with black stripe wire from the fuse block, an orange wire from the fuse block, the dark green wire going to the tank switch and a black wire that im not sure where it goes. The pink, orange, and green form a u shape and the black is off to the side. Next to the black is an unused terminal. The pink with black stripe and orange are from different terminals on the fuse block but are both hot in run. It seems there is a relay or something that should bridge the pink or orange to the dark green. Anyone have any ideas? The wire diagram only downloaded to page 7 after trying a couple of times. I tried to post a picture of the connector im talking about but its to many kb.

[Rip]

The connector terminals are female so whatever plugs into it would have 4 blades, 3 in a u shape and 1 by itself.

[Rip]

Hopefully someone recognizes it.

[bd]

I tried to post a picture of the connector im talking about but its to many kb.

Go here for a "How to" to resize pics.  You can also use MS Office Picture Manager packaged with some computers, etc.

Is this the connector you have plugged onto the selector switch (Delphi P/N-8911352 - pictured below)?

The wire diagram only downloaded to page 7 after trying a couple of times.

I've attached the auxiliary fuel tank wiring diagram in PDF format, below.

It seems it goes back to my first question. What might plug into the connector that the green wire goes to? There is a pink with black stripe wire from the fuse block, an orange wire from the fuse block, the dark green wire going to the tank switch and a black wire that im not sure where it goes. The pink, orange, and green form a u shape and the black is off to the side. Next to the black is an unused terminal. The pink with black stripe and orange are from different terminals on the fuse block but are both hot in run. It seems there is a relay or something that should bridge the pink or orange to the dark green.

In general, GM factory wire colors are:  Pink/Black = ignition; Orange = fused battery; Red = unfused battery; Black = ground.  Your setup isn't using the standard color combination for the fuel tank selector, so images will be very helpful if you can post them. 

In the meantime, if the connector on your selector switch appears as pictured (five terminals), then two wires attach to one side of the selector switch, and three wires attach to the adjacent side of the switch.  The 'two-wire side' controls ignition power to the selector valve.  The 'three-wire side' controls which tank sender is connected to the dash gauge.  If the connector isn't as pictured, then the second tank may have been added later and its wiring may not exactly follow the factory schematic(?).  So, post pics.

[bd]

Hopefully someone recognizes it.

Is that the connector off the switch, or off the fuse block, or...?

[Rip]

Thats the female connector that clips to the fuse block. The duel tanks are factory and the switch connection is the 5 wire with 2 on one side and 3 on the other.

[Rip]

This is it clipped on the fuse block above the direction flasher.

[Rip]

This is the back of it and you can see the space it clips to on the right side above the flasher.

[Rip]

The pink wire with the black stripe from the plastic connector at the top left corner goes to the connector, as well as the orange that is between the speaker wire and the yellow wire at the bottom right.

[Rip]

The dash switch has 5 wires coming off it, the dark green goes to the unknown connector,  the pink with white stripe, light green, blue, and pink go through the firewall like its supposed to, the only thing is instead of a pink  with black stripe wire going from the fuse block to the dash switch,  it goes to the connector and a dark green wire goes the dash switch. The connector seems factory in the way it attaches to the side of the fuse block.