Dual tanks: any way to manually force alternate tank - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SilveradoDude · 09-08-2019, 12:59 PM

I have the dual tank setup, the truck seems to default to the right hand (passenger side) tank. I have replaced the dash switch and the fuel line switch on the frame and I cannot get this to work predictably, and I need to switch to and use the left hand (driver side) tank. Anyway to do this?

sweetk30 · 09-08-2019, 07:10 PM

i modified my setup to pass side is a jerry can basicly . i used the tbi sender and pump that was in it to pump over to the driver side and dump in the filler neck vent hose tee i installed . i have it set up on a switch and a BIG red light under the radio so i do not forget its on . also its only feed power key on . so if the key is off it will not pump .

my driver side tank has i much higher psi pump and lines for it to feed my aftermarket edelbrock pro flo 4 efi setup .

in hind sight tho i wish i had set it up for right side main tank as most vehicles now are coming right side filler and pulling in to the pumps is a bit of fun when there full as everyone is driving for right side fill . and my efi lines could have been 3 feet shorter also .

**hatzie** · 09-08-2019, 08:58 PM

What year is your truck?

SilveradoDude · 09-09-2019, 01:33 PM

Quote:

Originally Posted by hatzie

what year is your truck?

85

**hatzie** · 09-10-2019, 10:34 PM

Quote:

Originally Posted by SilveradoDude

85

OK.
You should have a 1981-1991 NL2 dual tank setup.
This is the motorized valve that'll stay on the tank you select til you switch it.
Leave it set for the RH tank and use that tank. No need to play games with the hoses or the switch.

Dead Parrot · 09-08-2019, 09:36 PM

If it is an emergency type situation, just swap the left/right hoses on the tank valve. NOTE: If you do this, the gauge will now show the NOT IN USE tank as the gauge is switched by the switch and not the valve.

If you have one of the older style solenoid valves, they default to a non powered side, normally the passenger side. IIRC - the motor driven ones stay on the tank last selected when power is lost.

Alternative method. Just feed the hose(s) from the drivers side tank direct to the frame pipe, bypassing the valve.

kipps · 09-08-2019, 10:21 PM

Sweetk30, do you have a fuel gauge on your "jerry-can" at all? Seems like an odd way of plumbing things, but it is simple and it does work....

A note on the fuel tank sides. A reason to have the dominant tank(the one most often full) on the right side, is that it can counterbalance the driver. The fuel tank and the driver are the primary off-center loads in a vehicle, so you might as well have them on opposite sides. Of course, it doesn't matter much on a one ton.

SilveradoDude · 09-09-2019, 01:36 PM

Quote:

Originally Posted by Dead Parrot

If it is an emergency type situation, just swap the left/right hoses on the tank valve. NOTE: If you do this, the gauge will now show the NOT IN USE tank as the gauge is switched by the switch and not the valve.

If you have one of the older style solenoid valves, they default to a non powered side, normally the passenger side. IIRC - the motor driven ones stay on the tank last selected when power is lost.

Alternative method. Just feed the hose(s) from the drivers side tank direct to the frame pipe, bypassing the valve.

I'd love to do that but how can I get the gauge wired up to only read the driver side tank as well.

**hatzie** · 09-08-2019, 11:29 PM

If you have a 73-80 truck it's easy enough to change the AUX tank from the LH to the RH side.

Swap the supply and return hoses from the LH & RH senders on the valve.
Unplug the Packard plug from the switch.
-One side of the plug has a blocked off angled terminal hole and a RED and Green wire. This side powers the valve with the switch in the AUX position.
-The sender side of the plug has two angled terminals and one straight terminal. This is the sender switch. The output to the gauge is on the centre terminal and the wires from the senders are in the corners. Swap the corner wires to make the gauge read the proper tank after you swap the hoses around.

This is the dual tank theory of operation thread. It should answer a lot of questions.
http://67-72chevytrucks.com/vboard/s...d.php?t=754061

sweetk30 · 09-09-2019, 11:23 AM

i did install a autometer 2 1/16" z-series gauge for the jerry can tank yes .

09-08-2019, 12:59 PM	#1
SilveradoDude Registered User Join Date: Jun 2008 Location: None Posts: 184	Dual tanks: any way to manually force alternate tank I have the dual tank setup, the truck seems to default to the right hand (passenger side) tank. I have replaced the dash switch and the fuel line switch on the frame and I cannot get this to work predictably, and I need to switch to and use the left hand (driver side) tank. Anyway to do this?

09-08-2019, 07:10 PM	#2
sweetk30 Registered User Join Date: May 2012 Location: horseheads,ny rust belt Posts: 2,794	Re: Dual tanks: any way to manually force alternate tank i modified my setup to pass side is a jerry can basicly . i used the tbi sender and pump that was in it to pump over to the driver side and dump in the filler neck vent hose tee i installed . i have it set up on a switch and a BIG red light under the radio so i do not forget its on . also its only feed power key on . so if the key is off it will not pump . my driver side tank has i much higher psi pump and lines for it to feed my aftermarket edelbrock pro flo 4 efi setup . in hind sight tho i wish i had set it up for right side main tank as most vehicles now are coming right side filler and pulling in to the pumps is a bit of fun when there full as everyone is driving for right side fill . and my efi lines could have been 3 feet shorter also . __________________ 77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great.

09-08-2019, 08:58 PM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Dual tanks: any way to manually force alternate tank What year is your truck? __________________ 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.

09-08-2019, 09:36 PM	#6
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,611	Re: Dual tanks: any way to manually force alternate tank If it is an emergency type situation, just swap the left/right hoses on the tank valve. NOTE: If you do this, the gauge will now show the NOT IN USE tank as the gauge is switched by the switch and not the valve. If you have one of the older style solenoid valves, they default to a non powered side, normally the passenger side. IIRC - the motor driven ones stay on the tank last selected when power is lost. Alternative method. Just feed the hose(s) from the drivers side tank direct to the frame pipe, bypassing the valve.

09-08-2019, 10:21 PM	#7
kipps Registered User Join Date: Jul 2014 Location: North-central Virginia Posts: 1,104	Re: Dual tanks: any way to manually force alternate tank Sweetk30, do you have a fuel gauge on your "jerry-can" at all? Seems like an odd way of plumbing things, but it is simple and it does work.... A note on the fuel tank sides. A reason to have the dominant tank(the one most often full) on the right side, is that it can counterbalance the driver. The fuel tank and the driver are the primary off-center loads in a vehicle, so you might as well have them on opposite sides. Of course, it doesn't matter much on a one ton. __________________ 1987 C6P V20 truck, 2010 LMG 5.3, AFM delete, 2010 Camaro exhaust manifolds, 1997 nv4500, 1991 np241c, hydroboost, 2005 14bff axle & driveshaft, drop-n-lock gooseneck, 4.10 gears, stock suspension, rims, and tires. Still a work in progress. Any questions or suggestions are welcome!

09-08-2019, 11:29 PM	#9
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Dual tanks: any way to manually force alternate tank If you have a 73-80 truck it's easy enough to change the AUX tank from the LH to the RH side. Swap the supply and return hoses from the LH & RH senders on the valve. Unplug the Packard plug from the switch. -One side of the plug has a blocked off angled terminal hole and a RED and Green wire. This side powers the valve with the switch in the AUX position. -The sender side of the plug has two angled terminals and one straight terminal. This is the sender switch. The output to the gauge is on the centre terminal and the wires from the senders are in the corners. Swap the corner wires to make the gauge read the proper tank after you swap the hoses around. This is the dual tank theory of operation thread. It should answer a lot of questions. 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.

09-09-2019, 11:23 AM	#10
sweetk30 Registered User Join Date: May 2012 Location: horseheads,ny rust belt Posts: 2,794	Re: Dual tanks: any way to manually force alternate tank i did install a autometer 2 1/16" z-series gauge for the jerry can tank yes . __________________ 77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great.



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