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12-14-2009, 11:07 AM | #1 |
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Join Date: Sep 2008
Location: Middleton, Idaho
Posts: 352
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Dual gas tank switching problem
Hi,
I've been fighting my dual tank selector valve on my 1980 K20 for years now. The valve has 6 ports; 4 in and 2 out. I have searched everywhere and cannot find a replacement valve that has a single wire like mine. All 6 port universal replacement valves have a multi pin connector. So, my question is, what's the purpose of the extra 5/16 line on each tank? Could I cap those off and use a 3 port valve? Thanks. Last edited by dyno; 12-14-2009 at 11:22 AM. |
12-14-2009, 11:54 AM | #2 |
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Join Date: Jan 2009
Location: orangevale, ca
Posts: 3,626
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Re: Dual gas tank switching problem
how many ports does your sending unit have? mine have 2 on each unit. 1 is for fuel feed the other is for a vent and emissions that runs to the charcoal canister. my switching valve has 3 ports and 1 wire. i picked this up at oriellys. the only reason for a 6 port is for returned fuel.(fuel injection) so... take a look at these pics. you can either plug off the extra sets of ports(as long as you dont have a return line from the motor/fuel pump and put a vent on the sending units (if you dont have a canister) and figure out the wiring. or go buy a new valve with 3 ports and 1 wire. i hope this helps!
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"Dennis the Menace" 1978 Silverado (2wd, 1/2 ton, short bed)complete nut & bolt frame off restomod LQ9/4L80E MY LS SWAP/FRAME OFF BUILD BOOK 2006 TBSS way too much to list |
12-14-2009, 02:14 PM | #3 |
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Join Date: Jul 2008
Location: louisville, ky
Posts: 502
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Re: Dual gas tank switching problem
My '79 has a single wire just like yours. The right tank is unusable right now, so I've just been using the left. After troubleshooting and repairing the fuel gauge, the selector valve started getting ideas, and would just randomly cut off the fuel. My quick assesment of the fuel lines was that the smaller one is the return line. I can tell you that it had fuel in it, because it got all over my face while I was quickly bypassing the valve with some steel line and hose clamps. My plan is to eventually get the whole system working, so I would also like to see what people have come up with.
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12-14-2009, 05:30 PM | #4 |
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Join Date: May 2007
Location: CO
Posts: 475
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Re: Dual gas tank switching problem
You need an ACDelco p/n #467513. They're still available for about $70.
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12-14-2009, 10:24 PM | #5 |
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Join Date: Sep 2008
Location: Middleton, Idaho
Posts: 352
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Re: Dual gas tank switching problem
Hi,
Thanks for you guys' help. I tried to look up that AC Delco # it's available, but there was no description or pic for the part. My valve has 4 in, 2 out- total 6 ports, single wire. Can I block off the recirc. lines from the tank and fuel pump? What is the purpose of the fuel recirculating? If I can do that, I can use a 3 port valve. Thanks.
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"Built- not bought" 1958 GMC 150 4x4 in progress 1980 K20- Restored 1985 K3500 Flatbed 58 GMC 4x4 build thread: http://http://67-72chevytrucks.com/vboard/showthread.php?t=557675 |
12-14-2009, 10:27 PM | #6 |
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Join Date: Jan 2009
Location: orangevale, ca
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Re: Dual gas tank switching problem
where does the 2 lines go from the switch valve? 1 to the fuel pump the other to.....??
because technically you just have to plug off the unused 3 ports without having to buy a new valve since its a single wire unit.
__________________
"Dennis the Menace" 1978 Silverado (2wd, 1/2 ton, short bed)complete nut & bolt frame off restomod LQ9/4L80E MY LS SWAP/FRAME OFF BUILD BOOK 2006 TBSS way too much to list |
12-14-2009, 10:54 PM | #7 |
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Join Date: Jul 2008
Location: louisville, ky
Posts: 502
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Re: Dual gas tank switching problem
Go to www.oehq.com and type in the part number. Says in stock for $77.15. There's a picture on the left you can enlarge. Looks like a winner. Thanks Prong!
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12-15-2009, 10:24 AM | #8 | |
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Join Date: Sep 2008
Location: Middleton, Idaho
Posts: 352
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Re: Dual gas tank switching problem
Quote:
So I will probably order it and keep the lines the way they are. But I'm still curious as to why they installed a recirculation system on these trucks?
__________________
"Built- not bought" 1958 GMC 150 4x4 in progress 1980 K20- Restored 1985 K3500 Flatbed 58 GMC 4x4 build thread: http://http://67-72chevytrucks.com/vboard/showthread.php?t=557675 |
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12-15-2009, 04:30 PM | #9 |
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Join Date: Mar 2008
Location: Salt Lake City UT
Posts: 441
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Re: Dual gas tank switching problem
Dyno: Most likely for the charcoal cannister. Allows fuel vapor/fluid to return to the tank.
Zac: Thanks for the site....already solved an issue for me. Also note the free shipping for 75$+ orders. |
12-16-2009, 02:23 PM | #10 |
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Join Date: May 2007
Location: Idaho
Posts: 4
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Re: Dual gas tank switching problem
The return line (bypass) was added to prevent vapor locking.
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