The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 1973-1991 Dual fuel tank systems theory of operation

**hatzie** · 02-12-2018, 07:42 PM

Read the first post for how the gauge circuit works on the pre 1981 system.

The existing solenoid valve will not handle the pressure for the LS fuel injection.

You can't easily use the existing early dual tank wiring.

The easiest solution is to find or fab a 1987-1991 NL2 sub harness. The newer switch is probably larger than the hole. You're going to have to file it larger

02-12-2018, 07:42 PM	#18
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,913	Re: 1973-1991 Dual fuel tank systems theory of operation Read the first post for how the gauge circuit works on the pre 1981 system. The existing solenoid valve will not handle the pressure for the LS fuel injection. You can't easily use the existing early dual tank wiring. The easiest solution is to find or fab a 1987-1991 NL2 sub harness. The newer switch is probably larger than the hole. You're going to have to file it larger __________________ 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.