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fuel tank switch to transfer pump wiring diagram.

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fuel tank switch to transfer pump wiring diagram.

1980silver 1980silver
New User | Posts: 1 | Joined: 12/12
Posted: 12/08/12
08:00 PM

HELP!!! i have a 1980 silverado that the previous owner removed the transfer pump and most of the wiring. does anyone know how i can get a schematic or directions to install a new one ?  

waynep71222 waynep71222
User | Posts: 221 | Joined: 05/12
Posted: 12/08/12
10:04 PM

ok... are you talking about the six port dual fuel tank valve is...


how much of the wiring do you still have... it has a flat 5 pole weather pack connector...

Pollak fuel selector valves are 6 or 3 port valves which switch the fuel feed and return lines simultaneously. They operate by using an electric motor to drive the valves into position. Being motor driven, they have high closing pressures (65psi) and are suitable for applications with in-tank fuel pumps. The valves are stable in either position, only drawing current for a fraction of a second while the position is transferred. They manage the switching of both the supply and return of fuel from the selected tank along with the fuel gauge switching if required.

a double throw switch on the dash...

94187Ll 27  

waynep71222 waynep71222
User | Posts: 221 | Joined: 05/12
Posted: 12/08/12
10:13 PM

2007 04 25 203653 Gm 6 Port Fuel System  

muddobber1960 muddobber1960
New User | Posts: 1 | Joined: 02/13
Posted: 02/05/13
01:59 PM

I have a fuel gauge wiring issue on my 1980 K20 4x4 that pertains to this thread, however, it’s a different problem than 1980silver’s issue.    The gauge reads way past full whenever the ignition is on.

My wiring is different than the diagram from waynep71222.  Coming down the left frame rail I have a blue, a green, a tan and a pink wire.  

The blue goes to the left tank sending unit.  The tan goes to the right and the green goes to the switchover valve.  The pink then goes back up the right frame rail where it ends as a broken wire.

I can’t see where the other half of the wire may have been, or any indication of where it might have attached at the firewall.

My gauges and switchover valve were all working when I began work on this project, but now that it’s going back together, the gauge doesn’t work.  (Both sending units tested “bad” so I replaced both.)

Can anyone tell me where the pink wire goes to?  Any and all advice is greatly appreciated!  

waynep71222 waynep71222
User | Posts: 221 | Joined: 05/12
Posted: 02/05/13
11:59 PM

first... some of the images are bigger than can be seen..  move the slider or open each one in a new window by right clicking on it..

are you working with a six port fuel valve???

or the three port.. sounds like you have a six port..

the smallest diagram has the best diagram...

there are 5 wires into the fuel switch over valve..  but probably six cavities..

in looking at the small diagram blown up where i can see it...

the first cavity is blank...  the next two get the reversing power... one positive and the other negative or the switch reverses this to one negative and the other positive...

the next 3 are for the gauge and the units..

sending unit... dash gauge   sending unit...

so the order at the 6 pin connector using only 5 wires is

blank. /   pos or neg  /  neg or pos /   tank sender /   dash gauge  /  tank sender


i will dig out a 80s chevy truck wiring diagram in morning.. see if i can help more..  

waynep71222 waynep71222
User | Posts: 221 | Joined: 05/12
Posted: 02/06/13
07:16 AM

i did not find an 80 diagram.. but i found an 81 diagram.. it looks like its wired for a 3 port valve...

on the switch...

pink and black comes from the fuse box... power...

pink goes to the cluster fuel gauge

more to come while i sort out the diagram that is confusing...

seems there is a

light blue wire that goes to the aux fuel tank sending unit

tan and white wire goes to the main fuel tank sending unit..

a light green wire to the fuel control solenoid...

this seems to be the proper one for your 80 chevy truck...

let us know if this helps...

SW412 Fueltankselectorvalve Zpsa8ad12cf  

waynep71222 waynep71222
User | Posts: 221 | Joined: 05/12
Posted: 02/06/13
07:41 AM

the CUT pink wire in the frame might have been for a SINGLE tank truck only..

the dual tank sending unit switching is done at the 5 pin switch in the dashboard as seen above..

please ohm your light blue wire to the cab ground...  usually somewhere from 5 to 90 ohms is expected.

please ohm your Tan and white stripe wire  to the cab ground... again somewhere between 5 and 90 ohms...

are your tanks properly grounded...

is the ground strap from the cab to the frame rail usually at the right front cab mount intact and properly connected as the fuel tanks are grounded to the frame not the body...

how about the grounds between the battery negative and the inner fender well

and the back of the engine to the firewall.

print this test...  its an jpg image


VOLTAGE Drop Testing


run the tests...

add a 5th test...

5.   battery negative to the frame rail....  0.02 DC volts max...  

Serpico Serpico
New User | Posts: 1 | Joined: 02/13
Posted: 02/06/13
11:59 AM

It's always amazes me to the way people redesign the wheel...LOL...

Bob  AKA-pepsi1  

muddobber19601 muddobber19601
New User | Posts: 1 | Joined: 02/13
Posted: 02/07/13
02:06 PM

My truck has a 3-port valve and has only one wire (green) going to it.  It doesn't have the multi-wire plug.

Thank you for this info. I will test the grounds and the back of the switch as you have indicated and see where that gets me.  

kyis kyis
New User | Posts: 1 | Joined: 09/14
Posted: 09/05/14
01:25 PM

Having problems with 78 454 4wd fuel supply.
We replaced mechanical fuel pump with electric.
Seems like ever since the truck will run out of gas for no apparent reason.  Usually at startup, but can while driving also.
Cold or Hot and you can even hear the pump start clattering like it is out of gas before it dies, but it restarts after a while, also for no apparent reason.  Happens on both tanks.  Could this be related to blocking of return line or a bad switching valve.  I was going to try bypassing the tank switching valve next to see.  I've tried 3 different fuel pumps.  Its like it just starts sucking air for no reason.  Can't imagine vapor lock as it can happen pretty quick and when it's cold and you can be driving pretty hard and hot and not have problem.