wiring harness question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70inbville · 05-11-2019, 12:43 PM

Hello all,

is there a provision built into the under dash harness to add in dual fuel tank switch? I currently have a single tank truck and a dual tank bed and want to add a second tank. I have searched and must not be asking it right

thanks, Chip

Ziegelsteinfaust · 05-11-2019, 01:48 PM

No. Or at least it is not common. I had to make my own when I did it to a rcsb I had years ago.

70inbville · 05-11-2019, 03:19 PM

Quote:

Originally Posted by Ziegelsteinfaust

No. Or at least it is not common. I had to make my own when I did it to a rcsb I had years ago.

thanks for the reply. I have been searching in vain for a part number for the pigtail that plugs into the selector switch so I guess it is off to the scrap yard and search there!

**hatzie** · 05-11-2019, 06:14 PM

If you're retrofitting the NL2 system to a carbureted truck don't bother with the 73-80 single wire valve systems... get the 81-86 motorized valve system. The six port valves for the 73-80 single wire solenoid system are made of the rare element unobtainium.
If you've got fuel injection you need the 87-91 TBI harness with the in-tank fuel pump connections.

The GM harness plugs into the single tank sender wire on the RH frame rail. It gets power from the fuse panel and ground from the cab ground buss bar above the E-Brake pedal.
There's a disconnect at or near the firewall in the engine bay and a grommet to pass through the firewall.

This is the theory of operation writeup I made for the dual tank switching systems.
http://67-72chevytrucks.com/vboard/s...d.php?t=754061

70inbville · 05-12-2019, 11:15 AM

Thank you for the info and the link to your write-up! awesome info source for me and I appreciate the time.

05-11-2019, 12:43 PM	#1
70inbville Registered User Join Date: Oct 2011 Location: bartlesville ok Posts: 143	wiring harness question Hello all, is there a provision built into the under dash harness to add in dual fuel tank switch? I currently have a single tank truck and a dual tank bed and want to add a second tank. I have searched and must not be asking it right thanks, Chip

05-11-2019, 01:48 PM	#2
Ziegelsteinfaust Registered User Join Date: Dec 2012 Location: Temple City Posts: 3,566	Re: wiring harness question No. Or at least it is not common. I had to make my own when I did it to a rcsb I had years ago.

05-11-2019, 06:14 PM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,919	Re: wiring harness question If you're retrofitting the NL2 system to a carbureted truck don't bother with the 73-80 single wire valve systems... get the 81-86 motorized valve system. The six port valves for the 73-80 single wire solenoid system are made of the rare element unobtainium. If you've got fuel injection you need the 87-91 TBI harness with the in-tank fuel pump connections. The GM harness plugs into the single tank sender wire on the RH frame rail. It gets power from the fuse panel and ground from the cab ground buss bar above the E-Brake pedal. There's a disconnect at or near the firewall in the engine bay and a grommet to pass through the firewall. This is the theory of operation writeup I made for the dual tank switching systems. http://67-72chevytrucks.com/vboard/s...d.php?t=754061 __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

05-12-2019, 11:15 AM	#5
70inbville Registered User Join Date: Oct 2011 Location: bartlesville ok Posts: 143	Re: wiring harness question Thank you for the info and the link to your write-up! awesome info source for me and I appreciate the time.



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