Tank sending units - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**hatzie** · 10-05-2019, 06:23 PM

The DEPRESS FULLY switch is a momentary contact switch that springs back to OFF as soon as you let go of the switch.
I can't see how you could damage the motor in the valve.
It's a DC motor that spins different directions based on the polarity of terminals D & E.

The Dual Tank Theory of operation writeup may help clear things up for you. You have the 81-91 system in post #2.
http://67-72chevytrucks.com/vboard/s...d.php?t=754061

Dleslie212 · 10-07-2019, 09:16 AM

Quote:

Originally Posted by hatzie

The DEPRESS FULLY switch is a momentary contact switch that springs back to OFF as soon as you let go of the switch.
I can't see how you could damage the motor in the valve.
It's a DC motor that spins different directions based on the polarity of terminals D & E.

The Dual Tank Theory of operation writeup may help clear things up for you. You have the 81-91 system in post #2.
http://67-72chevytrucks.com/vboard/s...d.php?t=754061

Is there any harm in using a different switch? I just redid my entire fuel system, converting from the old style selector valve to the new style. But the switch i used has no OFF position, it’s ON-ON. I’m guessing the difference is that instead of the new valve only being powered for a second or so during switching, my valve is always getting power. Is that a bad thing?

10-05-2019, 06:23 PM	#1
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 5,022	Re: Tank sending units The DEPRESS FULLY switch is a momentary contact switch that springs back to OFF as soon as you let go of the switch. I can't see how you could damage the motor in the valve. It's a DC motor that spins different directions based on the polarity of terminals D & E. The Dual Tank Theory of operation writeup may help clear things up for you. You have the 81-91 system in post #2. 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.



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