The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 85 Silverado - Fuel Tank Selector Valve install

**hatzie** · 11-21-2018, 12:46 PM

The motorized valve doesn't change position til you put the correct polarity on E & F of the plug to turn the motor. A new valve shuttle could be anywhere in its' travel but the gauge should remain on one side or the other til the shuttle reaches the end of it's travel.

Usually the $13 polarity reversing dash switch is the problem with the 81-91 systems. Use the AC Delco D7809C 87-91 RV series switch. The 81-86 CK series switch isn't as reliable. https://www.amazon.com/ACDelco-D7089.../dp/B000EQU15Y

I would test that the RED and BLACK wires on the switch plug have juice.
The ground runs to the buss bar over the E-brake.
The Hot runs to an Ignition power accessory plug in the front of the fuse panel. If you look in the wiring diagrams it'll show where the fuse is and which position the factory put the NL2 harness power plug into.

11-21-2018, 12:46 PM	#7
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,919	Re: 85 Silverado - Fuel Tank Selector Valve install - no fuel The motorized valve doesn't change position til you put the correct polarity on E & F of the plug to turn the motor. A new valve shuttle could be anywhere in its' travel but the gauge should remain on one side or the other til the shuttle reaches the end of it's travel. Usually the $13 polarity reversing dash switch is the problem with the 81-91 systems. Use the AC Delco D7809C 87-91 RV series switch. The 81-86 CK series switch isn't as reliable. https://www.amazon.com/ACDelco-D7089.../dp/B000EQU15Y I would test that the RED and BLACK wires on the switch plug have juice. The ground runs to the buss bar over the E-brake. The Hot runs to an Ignition power accessory plug in the front of the fuse panel. If you look in the wiring diagrams it'll show where the fuse is and which position the factory put the NL2 harness power plug into. __________________ 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. Last edited by hatzie; 11-21-2018 at 12:54 PM.