The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-23-2016, 04:16 PM   #1
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
LS swap dual tank harness kits!

If anybody is interested, I literally just finished a 3-gang relay kit that replaces ALL of your existing dual tank wiring so that you can run (for example) 2 1987 TBI sending units and run 2 Walbro 255 fuel pumps. I'll be listing these shortly in the FS section with pics! Prices are $319.99 for these harnesses and include a NEW 65 psi GM style selector valve!
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-25-2016, 07:52 PM   #2
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

Here is the basic harness layout for it-there is a main IGN control relay and (2) fuel pump relays-a LH and RH. The control relay activates the selector switch and the pumps as well as the GM style 6-port selector valve-which btw is NOT your standard NOS GM valve or parts store replacement-the one I include is rated to 65 psi.
Attached Images
 
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-25-2016, 07:56 PM   #3
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

Closeup of part of the harness-this one has leads to plug directly into the pigtails from the Walbro style replacement fuel pumps when using an 87 style sending unit.
Attached Images
 
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-26-2016, 11:32 AM   #4
656mx
Registered User
 
Join Date: Sep 2014
Location: dutchess county NY
Posts: 61
Re: LS swap dual tank harness kits!

Do you sell it without the valve? I already bought and installed one for higher pressure. I was going to build my own harness but this would be a big time saver. It's for a ls swap 86 short bed.
656mx is offline   Reply With Quote
Old 07-26-2016, 12:50 PM   #5
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

Yes I can! Without the valve cost is $65 less on either kit!
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-26-2016, 12:59 PM   #6
656mx
Registered User
 
Join Date: Sep 2014
Location: dutchess county NY
Posts: 61
Re: LS swap dual tank harness kits!

You have more than one kit? Have a link or something? I'd like to see what you have.
656mx is offline   Reply With Quote
Old 07-26-2016, 01:09 PM   #7
foamypirate
Registered User
 
foamypirate's Avatar
 
Join Date: Apr 2009
Location: Pflugerville, TX
Posts: 594
Re: LS swap dual tank harness kits!

These look really nice, as always! I'll need to save some buckaroos, but I'd definitely be interested. I don't like the idea of my current factory setup where the Walbros are drawing all of their current through the 28 year old factory wiring and the selector switch.
foamypirate is offline   Reply With Quote
Old 07-26-2016, 01:45 PM   #8
MalibuSSwagon
Registered User
 
Join Date: Sep 2009
Location: Weare,NH
Posts: 1,503
Re: LS swap dual tank harness kits!

What valve are you using? Curious if it has the late model quick connect style fittings, would make plumbing easy.
MalibuSSwagon is offline   Reply With Quote
Old 07-26-2016, 07:21 PM   #9
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

No-not quick dis-connect....it has the standard barbed fittings but can still be used with SAE 30R9 rated clamp on fuel injection hose which is rated up to 180 psi. I just designed this kit so I dont have a link to it per se...just getting the word out I have them available now-both short and longbox fleet side.
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-27-2016, 09:27 AM   #10
656mx
Registered User
 
Join Date: Sep 2014
Location: dutchess county NY
Posts: 61
Re: LS swap dual tank harness kits!

I definitely want one. I will pm you in a few days.
656mx is offline   Reply With Quote
Old 07-27-2016, 10:04 AM   #11
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

Ok...sounds good!
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-27-2016, 02:57 PM   #12
ElGracho
Gentleman Jim Driver
 
ElGracho's Avatar
 
Join Date: Nov 2002
Location: Poulsbo, WA
Posts: 1,534
Re: LS swap dual tank harness kits!

These valves are rated to 65 psi and are plug and play to the 1987 GM fuel selector valves. If you buy one from AC Delco it will be marked Pollak just like the originals were. Many people have used these with the corvette fuel pressure regulator (58 psi) for LS/Late Vortec applications.

http://products.pollakaftermarket.co...n-valve/42-159
__________________
Joe
'75 GMC Gentleman Jim
'83 Chev C30 Crew Cab Dually
'84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter)
'85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans
'89 R3500 Flatbed
ElGracho is offline   Reply With Quote
Old 07-28-2016, 12:09 AM   #13
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

Quote:
Originally Posted by 656mx View Post
I definitely want one. I will pm you in a few days.
The harnesses I offer are both OEM replacements as well as upgrades for late model EFI swaps. Any questions you have let me know!
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 07-30-2016, 06:27 PM   #14
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

This LSx spec'd dual tank kit is going out tonight for a member in NM! I needed to finish drafting his harness diagram schematic for future troubleshooting and/or mods. On kits which significantly deviate from stock I design and include a color coded diagram using my graphics program-another benefit you don't get from the big harness companies! Then again, they don't offer what I do anyway!
Attached Images
 
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 08-24-2016, 01:15 PM   #15
BamaDave
Registered User
 
Join Date: May 2010
Location: Shoals, AL
Posts: 297
Re: LS swap dual tank harness kits!

does this use the factory selector switch that is mounted on the dash beside the ash tray?
BamaDave is offline   Reply With Quote
Old 08-24-2016, 03:04 PM   #16
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

It uses a factory style switch but must be on/off not momentary. As long as it does not say depress fully you're good. I thought I listed the AC Delco/GM part number for it....if not I can look it up-it's still in dealers for about $8-9.
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 01-29-2018, 08:23 PM   #17
Popeye75356
Registered User
 
Join Date: Jan 2016
Location: Marshall TX
Posts: 15
Re: LS swap dual tank harness kits!

Gmachinz,
I'm struggling a little and thought maybe you could lend some insight. I've taken the path of dual tanks on my 84' 5.3 swap with the following:
1. Walbro 255's in the tank
2. 87' tanks
3. 87' sending units
4. Pollak 42-159 6 port selector valve
Now I'm a little confused about how I'm going to power my in-tank pumps and also my OEM switch says "depress fully"????? Clearly I'm a green hat as this is the first time I've ever attempted a frame off so any help or suggestions would be greatly appreciated.

Thanks
Popeye
Popeye75356 is offline   Reply With Quote
Old 01-29-2018, 08:31 PM   #18
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

You need to use a 1987 fuel tank switch-the TBI trucks didnt use the depress fully switches-those were momentary and powered a shuttle valve inside the selector to open/close LH or RH fuel tanks ports.
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 01-29-2018, 09:56 PM   #19
Popeye75356
Registered User
 
Join Date: Jan 2016
Location: Marshall TX
Posts: 15
Re: LS swap dual tank harness kits!

gmachinz,
Do you know of any vendor that I can source an 87' harness and switch from?

Popeye
Popeye75356 is offline   Reply With Quote
Old 01-29-2018, 10:11 PM   #20
Popeye75356
Registered User
 
Join Date: Jan 2016
Location: Marshall TX
Posts: 15
Re: LS swap dual tank harness kits!

gmachinz,
Will your harness work as a "plug and play" solution with the 87' sending unit wiring ? If so do you have any available ? Looking to avoid the need to fabricate wiring based on this diagram that a Painless engineer drew for me today.

Popeye
Popeye75356 is offline   Reply With Quote
Old 01-29-2018, 11:02 PM   #21
gmachinz
Senior Member
 
Join Date: Jun 2011
Location: Des Moines, IA.
Posts: 4,025
Re: LS swap dual tank harness kits!

If you only need a harness w/o valve I’ve got them available! I’ll PM ya!
__________________
Specializing in building electrical harnesses and cooling systems

HARNESSWORX

"An army may march great distances without distress, if it marches through country where the enemy is not."

-Sun Tzu: The Art of War
gmachinz is offline   Reply With Quote
Old 01-31-2018, 09:28 PM   #22
Damien
Living the Dream
 
Damien's Avatar
 
Join Date: Mar 2007
Location: Farmington, MN
Posts: 912
Re: LS swap dual tank harness kits!

Quote:
Originally Posted by gmachinz View Post
No-not quick dis-connect....it has the standard barbed fittings but can still be used with SAE 30R9 rated clamp on fuel injection hose which is rated up to 180 psi. I just designed this kit so I dont have a link to it per se...just getting the word out I have them available now-both short and longbox fleet side.
You specifically state these are for fleet side trucks, are the parts any different for a step side?

I have been looking into a setup like this for a while and will be looking into this setup more next year when I get closer to putting the truck back together. I appreciate the information on the switch itself as well as I did not know the fuel injection switch was different than the carb. switch.
__________________
I can still count my vehicles on two hands.
Damien is offline   Reply With Quote
Old 03-11-2018, 12:58 PM   #23
Mattchu60
Registered User
 
Join Date: Jan 2014
Location: Swaledale, IA
Posts: 365
Re: LS swap dual tank harness kits!

I was reading the above - been considering swapping an LS into my truck with dual tanks. Got to ask about the stock fuel lines - would they be ok with the higher pressure pumps? I think the stock pumps are around 15 psi and LS needs about 58 psi. I would think stock steel lines are ok, but about about the rubber lines - would they need to be replaced with something else?
Mattchu60 is offline   Reply With Quote
Old 03-13-2018, 09:52 AM   #24
Mattchu60
Registered User
 
Join Date: Jan 2014
Location: Swaledale, IA
Posts: 365
Re: LS swap dual tank harness kits!

Anyone know if the stock lines will be fine at 60 psi? I think its gonna be ok - aftermarket hose appears to be rated at 100 psi or so.
Mattchu60 is offline   Reply With Quote
Old 03-15-2018, 01:49 PM   #25
RADustin
Senior Member
 
Join Date: Jun 2017
Location: New Orleans
Posts: 293
Re: LS swap dual tank harness kits!

you should replace the rubber lines when doing the swap. Also make sure the steel to rubber transition has some sort of hose barb. Sometimes I mildly fare the metal tube to bite the rubber.

Cheap insurance to avoid a fire or worse.
__________________
1949 Chevy 3100 P/U
http://67-72chevytrucks.com/vboard/s...d.php?t=302780

1976 GMC Sierra Classic C35 CCSB
http://67-72chevytrucks.com/vboard/s...25#post8188825
RADustin is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:36 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com