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#1 |
Registered User
Join Date: May 2013
Location: East Texas
Posts: 40
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Tank selector valve hose ID help?
Hello all,
The guy that I bought my truck from said the fuel gauge doesn't work and that only the driver side tank is hooked up. I've been researching how to fix the gauge, and took some pics of the tank selector valve. Two of the lines are not connected. Can you guys tell me what lines go where, and what are the two lines that are disconnected? Anybody have any diagrams? |
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#2 |
Registered User
Join Date: Jan 2010
Location: northern arizona
Posts: 259
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Re: Tank selector valve hose ID help?
My new selector valve came in today, and I was looking at the diagram that came with it and looked at the selector.
The selector itself says R on the housing, and L at the tip away from the selector body. But according to the diagram, it should be the other way. We both may find out we need to switch the lines after we hook it up. The 1/4" line is vent The 5/16" line is return from the fuel pump. The 3/8" line is fuel to the fuel pump. And do yourself a favor, install an inline fuel filter in both lines from the tank before the selector (also voids warranty if filters are not installed). I wish my scanner would work, I would include a diagram, but I believe one of the other members who has it will be along soon and they can post it for you.
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"Off the grid and on the seven day weekend plan" "One person cannot know everything, but between all of us, there isn't much we don't know." |
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#3 | |
Registered User
Join Date: Jun 2014
Location: Orlando Florida
Posts: 1,598
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Re: Tank selector valve hose ID help?
I would assume each line hooks to the bare nipple they are pointing at. Looks like they bypassed it by hooking them together. But, that's just my assumption. I have to inspect that myself on my truck, the guy I got it from said the passenger side tank doesn't work but I haven't even tried it yet.
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#4 |
Registered User
Join Date: Jan 2010
Location: northern arizona
Posts: 259
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Re: Tank selector valve hose ID help?
From the diagram that came with my selector:
Dang it, should have used larger font. I hope you can read it.
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"Off the grid and on the seven day weekend plan" "One person cannot know everything, but between all of us, there isn't much we don't know." Last edited by MountainGoat1966; 08-08-2014 at 10:54 PM. Reason: font too small |
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#5 |
Registered User
Join Date: Nov 2009
Location: Haines City FL
Posts: 461
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Re: Tank selector valve hose ID help?
This should give you a good reference
http://67-72chevytrucks.com/vboard/s...d.php?t=512849 ![]() |
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#6 |
Registered User
Join Date: May 2013
Location: East Texas
Posts: 40
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Re: Tank selector valve hose ID help?
Dumb question. Why is there a return line? What is its purpose?
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#7 |
Moderator
![]() Join Date: Oct 2008
Location: Wentworth, NH
Posts: 4,951
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Re: Tank selector valve hose ID help?
It's supposed to stop vapor lock.
Your lines with the plastic Tee are the vapor cannister lines. They are hooked up all the time. Looks like the PO bypassed the feed line. BTW the most common failure is the switch not the valve. Not saying the valve can't be bad but it's way more common for that dash switch to fail. GM used a momentary switch that returns to center on the 81-86 trucks that says Depress Fully. You need to hold this switch in the position you're switching to for at least 10-15 full seconds. This is completely unnecessary. The Pollack valve has internal micro-switches and diodes to switch off the valve motor as soon as the shuttle has reached the end of its' travel. You can, and should, use the 87-91 R/V series TBI switch, AC Delco D7089C, for all 81-91 square trucks. Tell the parts guy you have an '87 with a 350 or 5.7L. The 87-91 R/V series TBI switch doesn't say Depress Fully. It stays switched and works just fine. ↓↓↓↓↓↓↓ Internal switch Schematic of Pollack Motorized Valve A, B, C are gauge switch D, E are the valve motor ↓↓↓↓↓↓↓ ![]() ↓↓↓↓↓↓↓ Cutaway from the Pollack datasheet showing return and feed nipples ↓↓↓↓↓↓↓ ![]()
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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...
And please let us know if and how your repairs were successful. Last edited by hatzie; 08-15-2014 at 09:54 PM. |
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#8 |
Registered User
Join Date: May 2013
Location: East Texas
Posts: 40
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Re: Tank selector valve hose ID help?
Please forgive me, the truck is a 1983 Silverado with a 350. Thank you for the help guys! I realized that the PO bypassed the tank selector valve altogether. He is drawing fuel from the fuel tank directly to the fuel pump. My guess is that the valve probably failed, and he decided to bypass instead of replace it. Another question, if i might? Where does the return line from the engine come from???? Trying to truly fully understand the fuel delivery system...
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#9 |
Moderator
![]() Join Date: Oct 2008
Location: Wentworth, NH
Posts: 4,951
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Re: Tank selector valve hose ID help?
Off the fuel pump.
There are three lines on the fuel pump Supply, Return, and Carburetor. I'd change the $14 switch before spending $110 on a valve. The valve is expensive and not usually the problem.
__________________
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...
And please let us know if and how your repairs were successful. |
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#10 |
Registered User
Join Date: May 2013
Location: East Texas
Posts: 40
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Re: Tank selector valve hose ID help?
Thank you hatzie. I changed the switch last week, and it still doesn't work.
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