ditching dual tank selector valve & all unneeded wiring - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SYCOTIK · 11-04-2011, 04:38 PM

Hey guys. Lookin for a little advice so I'm gonna try to explain best I can without the help of pics. I'm putting all the wiring back in my truck now, and tryin to get rid of things I don't need. Its an '87 tbi that had dual tanks. I put in a fuel cell a while back, but just ran one of the tank lines from the selector valve to the cell. Now I want to ditch that valve along with all wiring/ switches that have to do with it. I tried to figure out the wiring diagram from the chiltons manual, but wanted some extra input before I start removing wires I may need later. So from the firewall plug, there's 7 wires, 4 going to taillights, 3 for fuel system (2- tan/white, 1 pink). 1 of the tan/whites plugs into another small harness that goes to the tank selector switch on the dash, which I want to do away with. The other tan/white and pink wires go back to a plug. The other end of the plug, the wires go into the valve selctor harness with a couple other wires. I know the pink wire goes the sending unit, and I think the tan/white is fuel pump?
So now my question. Can I just run the pink directly to the sending unit on the fuel cell and the tan/white to the fuel pump (if that's what that wire goes to)? And then I could remove all the othere unneeded wires that connect anywhere within those?
Sorry if that just confused anybody lol. If any of that isn't correct or if anyone needs some more info to help lemme know and ill try and get it. Thanks guys
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pig rig · 11-04-2011, 05:43 PM

just a heads up if you haven't figured it out already but the dash switch not only does it select the tank but it also turns the pump on and off for the selected tank

maskale · 11-05-2011, 05:27 AM

They only way to be sure is test it.

Make estensions or pull all ur wires to the driver door. Figure which wire does what and label them. And get a note pad also to write your test results down.

Now buy testing make sure all ur labels are correct. U need a test light and a sending unit. Use the test light to make sure ur fuel pump gets 12v when u put the key in ON. Also hook up the sending unit and make sure it works correctly, even move the float and watch ur gauge to make sure it moves, sending unit needs a ground during test.

If u want to remove the switch u just need to to figure which wires to connect together. After u splice those wires run ur test again to make sure everything is right.
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**hatzie** · 11-05-2011, 05:59 PM

Yes. You read the diagram correctly. The solid pink wire is the main sender wire and tan/white is the tank switch power feed.

Attached is a 1989 GM TBI dual tank wiring diagram. I believe the dashed lines indicate the wiring and plug for a single tank TBI setup.

SYCOTIK · 11-05-2011, 06:56 PM

Thanks for the responses guys. Testing the wires isn't really an option at this point since I'm just starting to put all the wiring back in, so there's zero power to the truck and half of the harnesses aren't even in. I was just hoping to do away with things at this point instead of going back thru again later, but I guess that's what ill have to do or just deal with extra wires...
Hatzie, I'm havin trouble getting ur attachment to open for some reason. Could u try emailing it to me? Layedout87@comcast.net
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**hatzie** · 11-06-2011, 08:29 AM

Vehicle power isn't needed to chase wires. You need a good wiring diagram set and a volt ohm meter with a continuity buzzer mode.
You can use a self-powered continuity test light but they cost more than a volt ohm meter.

Buzz or ohm the pink wire to the fuel gauge signal wire in the dash.
Buzz or ohm the tan/wht wire to the IGN connection on the fuse panel.

11-04-2011, 04:38 PM	#1
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	ditching dual tank selector valve & all unneeded wiring Hey guys. Lookin for a little advice so I'm gonna try to explain best I can without the help of pics. I'm putting all the wiring back in my truck now, and tryin to get rid of things I don't need. Its an '87 tbi that had dual tanks. I put in a fuel cell a while back, but just ran one of the tank lines from the selector valve to the cell. Now I want to ditch that valve along with all wiring/ switches that have to do with it. I tried to figure out the wiring diagram from the chiltons manual, but wanted some extra input before I start removing wires I may need later. So from the firewall plug, there's 7 wires, 4 going to taillights, 3 for fuel system (2- tan/white, 1 pink). 1 of the tan/whites plugs into another small harness that goes to the tank selector switch on the dash, which I want to do away with. The other tan/white and pink wires go back to a plug. The other end of the plug, the wires go into the valve selctor harness with a couple other wires. I know the pink wire goes the sending unit, and I think the tan/white is fuel pump? So now my question. Can I just run the pink directly to the sending unit on the fuel cell and the tan/white to the fuel pump (if that's what that wire goes to)? And then I could remove all the othere unneeded wires that connect anywhere within those? Sorry if that just confused anybody lol. If any of that isn't correct or if anyone needs some more info to help lemme know and ill try and get it. Thanks guys Posted via Mobile Device

11-04-2011, 05:43 PM	#2
pig rig Registered User Join Date: Feb 2009 Location: washington the state Posts: 730	Re: ditching dual tank selector valve & all unneeded wiring just a heads up if you haven't figured it out already but the dash switch not only does it select the tank but it also turns the pump on and off for the selected tank __________________ my sports car rolls on six wheels only because I'm to fat to get in and out of new corvette http://hubgarage.s3.amazonaws.com/ph...ped_detail.JPG

11-05-2011, 05:27 AM	#3
maskale Registered User Join Date: Jul 2011 Location: Houston, Tx Posts: 159	Re: ditching dual tank selector valve & all unneeded wiring They only way to be sure is test it. Make estensions or pull all ur wires to the driver door. Figure which wire does what and label them. And get a note pad also to write your test results down. Now buy testing make sure all ur labels are correct. U need a test light and a sending unit. Use the test light to make sure ur fuel pump gets 12v when u put the key in ON. Also hook up the sending unit and make sure it works correctly, even move the float and watch ur gauge to make sure it moves, sending unit needs a ground during test. If u want to remove the switch u just need to to figure which wires to connect together. After u splice those wires run ur test again to make sure everything is right. Posted via Mobile Device

11-05-2011, 06:56 PM	#5
SYCOTIK Registered User Join Date: Feb 2011 Location: Vacaville, CA Posts: 34	Re: ditching dual tank selector valve & all unneeded wiring Thanks for the responses guys. Testing the wires isn't really an option at this point since I'm just starting to put all the wiring back in, so there's zero power to the truck and half of the harnesses aren't even in. I was just hoping to do away with things at this point instead of going back thru again later, but I guess that's what ill have to do or just deal with extra wires... Hatzie, I'm havin trouble getting ur attachment to open for some reason. Could u try emailing it to me? Layedout87@comcast.net Posted via Mobile Device

11-06-2011, 08:29 AM	#6
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,950	Re: ditching dual tank selector valve & all unneeded wiring Vehicle power isn't needed to chase wires. You need a good wiring diagram set and a volt ohm meter with a continuity buzzer mode. You can use a self-powered continuity test light but they cost more than a volt ohm meter. Buzz or ohm the pink wire to the fuel gauge signal wire in the dash. Buzz or ohm the tan/wht wire to the IGN connection on the fuse panel.



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