Help with dual fuel tanks - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Zoerb · 03-01-2006, 01:50 AM

I am having a problem with a truck I just bought.
Its an 84 Chevy K20 4x4 with a 350 and dual tanks.
The switch on the dash doesnt seem to do anything, doesnt switch tanks, and the gauge stays at 1/8 tank (doesnt bounce when the switch is pushed). Where should I start?

I had an 86 Chevy pk that had dual tanks, and when I would push the switch, you could hear the valve switch. On the 84 I dont hear a thing.

Any suggestions?

79BIG10 · 03-01-2006, 01:55 AM

To me it sounds like more the swich itself. Get one from a dealership or a AC Delco store. Most auto places don't carry it. I went ahead and got a new cover while I was there with the speed nuts (make their own thread on the plastic studs). Take out the ashtray and unbolt it out of the way. It's a PITA to get to but there are two studs that the speed nuts are threaded onto. Best way is to unplug the wiring harness to the plug and move out of the way. I ended up breaking my switch cover studs (hence the new cover

) and take out the switch. Then place the new switch in the way the other came out making sure driver and passenger side being the same position as before. Then place the cover on and turn the nuts on the studs. They will be hard to turn but they will make their own threads.

If this doesn't solve it then the valve be bad. Easy way to check it is take a test light to the wiring. The valve is under the passenger side near where the cab and bed meet inside the frame rail. Not sure what wiring setup you have on that truck but if it was like mine it's a green wire going to it. When you flip the tank switch to the driver side it powers the valve to take from the driver side. Mine ended up being a loose wire on the fuse panel (pink with black stripe) that powered the switch itself. If it's the one wire setup this is the easiest way to check- take the green wire off and take the test light to it to see if it comes on with the key turned over (not running) and the driver side switch pressed. If it doesn't come on then it's either a wiring issue or a fuse. If it does come on then it's a bad valve.

**Captkaos** · 03-01-2006, 05:50 PM

I would start by first pulling the switch apart and checking the contacts. It is cheaper than replacing the switch. Typically they are either dirty or have poor contact. Here is a picture step by step of how to do it. After you clean it up, make sure you put some di-electric grease back in there:

Breakdown of parts:

Assmebly:

03-01-2006, 01:50 AM	#1
Zoerb Registered User Join Date: Dec 2005 Location: Wasilla Alaska Posts: 73	Help with dual fuel tanks I am having a problem with a truck I just bought. Its an 84 Chevy K20 4x4 with a 350 and dual tanks. The switch on the dash doesnt seem to do anything, doesnt switch tanks, and the gauge stays at 1/8 tank (doesnt bounce when the switch is pushed). Where should I start? I had an 86 Chevy pk that had dual tanks, and when I would push the switch, you could hear the valve switch. On the 84 I dont hear a thing. Any suggestions? __________________ 2017 Tahoe Premier - Daily '99 Silverado 2500 Wife's whip- 2020 Equinox Premier

03-01-2006, 01:55 AM	#2
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,774	Re: Help with dual fuel tanks To me it sounds like more the swich itself. Get one from a dealership or a AC Delco store. Most auto places don't carry it. I went ahead and got a new cover while I was there with the speed nuts (make their own thread on the plastic studs). Take out the ashtray and unbolt it out of the way. It's a PITA to get to but there are two studs that the speed nuts are threaded onto. Best way is to unplug the wiring harness to the plug and move out of the way. I ended up breaking my switch cover studs (hence the new cover ) and take out the switch. Then place the new switch in the way the other came out making sure driver and passenger side being the same position as before. Then place the cover on and turn the nuts on the studs. They will be hard to turn but they will make their own threads. If this doesn't solve it then the valve be bad. Easy way to check it is take a test light to the wiring. The valve is under the passenger side near where the cab and bed meet inside the frame rail. Not sure what wiring setup you have on that truck but if it was like mine it's a green wire going to it. When you flip the tank switch to the driver side it powers the valve to take from the driver side. Mine ended up being a loose wire on the fuse panel (pink with black stripe) that powered the switch itself. If it's the one wire setup this is the easiest way to check- take the green wire off and take the test light to it to see if it comes on with the key turned over (not running) and the driver side switch pressed. If it doesn't come on then it's either a wiring issue or a fuse. If it does come on then it's a bad valve. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson Last edited by 79BIG10; 03-01-2006 at 02:02 AM.

03-01-2006, 05:50 PM	#3
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: Help with dual fuel tanks I would start by first pulling the switch apart and checking the contacts. It is cheaper than replacing the switch. Typically they are either dirty or have poor contact. Here is a picture step by step of how to do it. After you clean it up, make sure you put some di-electric grease back in there: Breakdown of parts: Assmebly: __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com Last edited by Captkaos; 03-01-2006 at 05:50 PM.



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