1980 k30 fuel tank wiring - The 1947 - Present Chevrolet & GMC Truck Message Board Network

80crew454 · 01-31-2015, 10:21 PM

Hey guys I'm a new member to the forum but have been looking on here for a long time and first off would like to say thanks for all the great info and tips you guys rock.

Now for my question I have duel tanks on my k30. There are 4 wires that come out of my firewall and down the drivers side frame one wire(can't remember the color)goes to the driver side sending unit then the next three cross over to the passenger side where the second wire goes to the passenger side sending unit the third wire goes to tank selector valve. Here's where I get lost the 4th wire (pink I believe) goes back up the passenger frame rail across the back of the transmission and appears to go into the main wire harness block.

Is this a power wire? If so why run it all the way down bolth Frame rails and back up it appears to be factory wiring

Thanks for any help

chengny · 02-01-2015, 01:45 AM

Here is the wiring diagram for your (pre-1981) dual tank system:

Is it possible that the wire that runs down (on the driver's side) and back up to the cab (on the RH side) is tan - rather than pink?

It appears that this is the switched sensing leg for the dash gauge. But as you note, it looks like it needlessly runs out through the firewall, all the way down to the Pollak valve, back up the passenger's side and then re-enters the cab (without ever connecting to anything between the select switch and the gauge).

It would seem that this wire could have been led directly over to the dash gauge - without ever leaving the cab.

greg64 · 02-01-2015, 11:43 AM

I'm guessing the wiring was run that way so that the fuel gauge and firewall bulkhead connector would be the same on every truck (dual tank or single tank) to make manufacturing easier.

80crew454 · 02-01-2015, 02:55 PM

I was pretty sure it was pink but it could be tan. I'm just not a fan of having a single strand wire going down the frame so I'll prob just eliminate it going down both Frame rails and connect it at the firewall. I'm fixing all the rest of the wiring so I can't put a batt in it to test if it was a power or sensing wire.

01-31-2015, 10:21 PM	#1
80crew454 Registered User Join Date: Jan 2015 Location: selah wa Posts: 2	1980 k30 fuel tank wiring Hey guys I'm a new member to the forum but have been looking on here for a long time and first off would like to say thanks for all the great info and tips you guys rock. Now for my question I have duel tanks on my k30. There are 4 wires that come out of my firewall and down the drivers side frame one wire(can't remember the color)goes to the driver side sending unit then the next three cross over to the passenger side where the second wire goes to the passenger side sending unit the third wire goes to tank selector valve. Here's where I get lost the 4th wire (pink I believe) goes back up the passenger frame rail across the back of the transmission and appears to go into the main wire harness block. Is this a power wire? If so why run it all the way down bolth Frame rails and back up it appears to be factory wiring Thanks for any help

02-01-2015, 01:45 AM	#2
chengny Registered User Join Date: May 2007 Location: New Hampshire Posts: 349	Re: 1980 k30 fuel tank wiring Here is the wiring diagram for your (pre-1981) dual tank system: Is it possible that the wire that runs down (on the driver's side) and back up to the cab (on the RH side) is tan - rather than pink? It appears that this is the switched sensing leg for the dash gauge. But as you note, it looks like it needlessly runs out through the firewall, all the way down to the Pollak valve, back up the passenger's side and then re-enters the cab (without ever connecting to anything between the select switch and the gauge). It would seem that this wire could have been led directly over to the dash gauge - without ever leaving the cab.

02-01-2015, 11:43 AM	#3
greg64 Registered User Join Date: Dec 2007 Location: Kimberley, BC, Canada Posts: 799	Re: 1980 k30 fuel tank wiring I'm guessing the wiring was run that way so that the fuel gauge and firewall bulkhead connector would be the same on every truck (dual tank or single tank) to make manufacturing easier. __________________ Greg 64 GMC Suburban - 283, NV3500, 14 bolt 77 C10 swb - 292, SM465, 12 bolt

02-01-2015, 02:55 PM	#4
80crew454 Registered User Join Date: Jan 2015 Location: selah wa Posts: 2	Re: 1980 k30 fuel tank wiring I was pretty sure it was pink but it could be tan. I'm just not a fan of having a single strand wire going down the frame so I'll prob just eliminate it going down both Frame rails and connect it at the firewall. I'm fixing all the rest of the wiring so I can't put a batt in it to test if it was a power or sensing wire.



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