1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Fuel tank selector valve 2 types?

Discussion in 'Tech Discussion' started by mavtricks71, Dec 31, 2017.

  1. mavtricks71

    mavtricks71 Full Access Member

    Posts:
    178
    Likes Received:
    30
    Joined:
    Jun 29, 2016
    Location:
    az
    First Name:
    mike
    Truck Year:
    1986
    Truck Model:
    k10
    Engine Size:
    350
    Ok I'm confused....did they use 2 types of Fuel sector valves? I see people talking about the 1 wire...my truck has a harness type plug in. I need to replace mine My trucks an 86 will the aftermarket ones work?
     
  2. bucket

    bucket Super Moderator Staff Member

    Age:
    37
    Posts:
    19,426
    Likes Received:
    4,248
    Joined:
    Aug 3, 2010
    Location:
    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    The aftermarket ones should work I think. IIRC, the last year for the 1-wire solenoid type was '84.
     
  3. 78C10BigTen

    78C10BigTen Full Access Member

    Posts:
    5,497
    Likes Received:
    3,342
    Joined:
    Apr 12, 2017
    Location:
    pennsylvannia
    First Name:
    ted
    Truck Year:
    1978
    Truck Model:
    C10 BIG TEN
    Engine Size:
    350
    When i had researched my selector valve for my 78 everything kept coming up universal with the only differance being 3 port or 6 port.
     
  4. hatzie

    hatzie Full Access Member

    Age:
    52
    Posts:
    557
    Likes Received:
    385
    Joined:
    Dec 6, 2011
    Location:
    NH
    First Name:
    David
    Truck Year:
    1976
    Truck Model:
    k20
    Engine Size:
    6.5
    Actually there were three valves used between 1973 & 1991. None of the systems are rocket science to repair once you understand what makes em tick.

    On both systems...
    -The fuel is routed from one of the tanks to a common OUT port. Only one tank at a time is valved open to the output port and the other half of the valve to the return port
    -On systems with a return line... The return line should be routed to the tank that fuel is being drawn from. If you mix up the return lines you can overfill the tank not being used. Hosing down the guy in the next lane with raw fuel may not garner a friendly reaction.
    -Both LH tank lines into the same side and both RH fuel lines into the opposite side.
    -To-The-Engine only has 2 lines. Feed and Return.

    **
    1973 & 1974 & some 1975 had a cable operated valve with a SPDT switch behind the dash knee panel that activated via the cable to run the fuel gauge. If you google it you'll find a thread on Chris's board about the valves with pictures of this setup. This is LONG obsolete. Folks replaced them with the 75/76-80 system when the parts ran out but there are a few survivors.

    **
    1975/76-1980 used a single wire solenoid valve with three or six ports.
    --The valves returned to a rest position as soon as power was removed. In 1980 GM added a retained power relay to keep the valve energized in the AUX position while cranking.
    --Six port valve was used on trucks that came with return lines.
    --Three port valves were for trucks without return lines.
    --Both valves are obsolete. Standard Motor Products sells a three port version but there are no six port solenoid valves available. Folks have used the 1981-1991 Pollack valves but generally they butcher the wiring.

    -Four wires run through the firewall.
    --Two tank sender wires.
    --One Dash Gauge feeder wire.
    --One Solenoid Valve power wire.

    -The dash switch is a five terminal DPDT (Double Pole Double Throw) ON-ON rocker switch.
    ----Each switch is called a pole and each switch position is called a throw...
    ------Double Pole means there are two switches actuated by one rocker.
    ------Double Throw means there are two different switch positions with a common input or output terminal.
    ------ON-ON means there are two ON positions with no centre OFF position.
    --The reason there are five and not six terminals is to key the switch to the connector such that it can only be plugged in one way. You can use a standard 6 terminal DPDT ON-ON rocker or toggle switch by clipping off one of the switch terminals to match the original switch.
    --On the three terminal side of the switch there's one wire direct to the dash gauge in the common position and the fuel level sender wires to the switched terminals. This selects which sender is routed to the dash gauge.
    --The two terminal side of the switch is still a double throw switch but it's missing one of the switch terminals to key the connector. This is so it can't be plugged in backwards. It also assures that the unwashed masses will buy switches from GM and not McMaster Carr or Grainger or... It has one power wire from the fuse panel, or a relay in 1980, on the centre common terminal and a green wire that routes power to the solenoid valve when the switch is set in the AUX position.

    **
    1981-1991 squares used a six port motorized valve made by Pollack. These are still being produced by Pollack on Jan 1st 2018.
    -The "universal" valves that claim they're three port usually have all three return line ports capped. You can use either just be sure to cap any unused ports to keep dirt out of the valve guts.
    -The later motorized valve remains in the last switched position unlike the earlier solenoid valves.
    [​IMG]


    Electrical;
    -The Pollack valve uses five of six cavities in a Six position Weatherpack plug. A-E are used. F is plugged with a seal.
    -Internal to the valve are two diodes to prevent power being routed to the motor from D or E once the valve shuttle has reached the end of its' travel.
    -The motorized valve has a SPDT switch to control which sender feeds the gauge shortening the wiring considerably.
    ----The gauge/Sender wires are on positions A, B, & C of the valve.
    ------Senders from the tanks are on switched terminals A & C.
    ------The gauge output is on Terminal B. This wire runs to the molded sender wire connector on the RH frame rail. It allowed GM to just drop in the NL2 as a sub harness without having two main harnesses.
    [​IMG]


    Motorized tank switch details...
    [​IMG]
    -The above switch is a generic Polarity Reversing DPDT switch used to turn DC motors backwards. GM used a proprietary switch but this picture exposes what the GM switch actually is doing.
    --Two of the switch contacts do not have terminals. These contacts are bridged back to the other switched terminals diagonally across the switch.
    --Output to the DC motor in the valve comes from the common terminals of the switch.
    --Power and Ground run to one switched terminal of each half of the switch.
    --When the switch is toggled to the opposite position the LH & RH MOTOR terminals of the switch reverse polarity. + becomes - and - becomes +. The valve motor then runs in the direction dictated by the polarity it's receiving on D & E til the stop on the valve shuttle cams the internal gauge and motor switches over to the switch leg with a diode that blocks the incoming current. The motor then stops til the dash switch is toggled back to the opposite position.
    --1981-1996 used The AC Delco D7003 Momentary ON-OFF-ON switch that has "DEPRESS FULLY" emblazoned on the bezel. DO NOT USE THE D7003 SWITCH... I ALWAYS REPLACE WITH THE AC Delco D7809 or Standard DS-1807 1987-1991 R/V 10-30 "TBI" ON-ON switch.

    Since the 1975/76-1991 NL2 dual tank systems used a sub-harness that plugs into the RH tank sender wire on the RH frame rail and the fuse panel under the dash. It's fairly easy to retrofit and or update to the later model system.

    You can swap a 1981 -1991 motorized Pollack valve sub harness into a 73-80 truck. You need the entire later model NL2 sub harness from the fuse panel/ground bar to the dash switch. Two wires run through the firewall to the valve and one wire from terminal B of the valve to the RH frame rail disconnect of the "production tank" sender wire.

    BTW I've used the Delphi Packard 56 switch plug for a 73-80 system on a generic polarity reversing switch and rolled my own harness to convert a single tank truck to a dual tank truck. Much easier to drill a 1/2" hole for a generic polarity reversing toggle switch than cut and file a square hole for a GM rocker switch. The toggle pointed to the enabled tank so no bezel was required.
     
    Last edited: Jan 1, 2018
  5. mavtricks71

    mavtricks71 Full Access Member

    Posts:
    178
    Likes Received:
    30
    Joined:
    Jun 29, 2016
    Location:
    az
    First Name:
    mike
    Truck Year:
    1986
    Truck Model:
    k10
    Engine Size:
    350
    Wow lots of info there Thank you....Good enough to print out
     
  6. mavtricks71

    mavtricks71 Full Access Member

    Posts:
    178
    Likes Received:
    30
    Joined:
    Jun 29, 2016
    Location:
    az
    First Name:
    mike
    Truck Year:
    1986
    Truck Model:
    k10
    Engine Size:
    350
    There are different brands Echlin , Standard Motors , Delco ....anybody know wich is best?
     
  7. hatzie

    hatzie Full Access Member

    Age:
    52
    Posts:
    557
    Likes Received:
    385
    Joined:
    Dec 6, 2011
    Location:
    NH
    First Name:
    David
    Truck Year:
    1976
    Truck Model:
    k20
    Engine Size:
    6.5
    All three you mention are top shelf suppliers. You'd be safe with any of the three.
    AFAIK most of them are re-boxed Pollack valves. The Standard Motor FV5 & AC Delco U7000 Professional were both Pollack valves in 2004 when I installed mine on my 1976. Things often change so I welcome more recent proof to the contrary.
    That being said. I'd stick with Delco Professional... As long as it's not coming from China or India or some other bottom tier manufacturing nation.

    You could buy manual Moeller or Groeco Marine fuel valves and put in two fuel gauges.
    I honestly thought about re-purposing an oil pressure gauge in my tach dash and co-opting the Volt gauge slot for the RH tank then running both sender wires up to the dash.
    I also entertained thoughts of putting a pair of 90Ω VDO fuel gauges in the center AC duct position and running a clock in the lower left gauge hole. You could also probably source a Marine or Aviation gauge with two fuel needles or LED bars. The last option would probably look a bit early modern industrial so it would look more at home in the spartan interior of the M1008 than in my posh 76 Silverado LOL.
     
    Last edited: Dec 31, 2017
  8. mavtricks71

    mavtricks71 Full Access Member

    Posts:
    178
    Likes Received:
    30
    Joined:
    Jun 29, 2016
    Location:
    az
    First Name:
    mike
    Truck Year:
    1986
    Truck Model:
    k10
    Engine Size:
    350
    Yea updating the gauges would be cool a lot of people are doing that these days....seems everything I buy " ac delco" is made in china my electric door motor wich gave me hell.... and my ac delco master cylinder was made in China.... I'm just gonna specify on box where its made and buy one NOT made in china.
     
    hatzie likes this.
  9. hatzie

    hatzie Full Access Member

    Age:
    52
    Posts:
    557
    Likes Received:
    385
    Joined:
    Dec 6, 2011
    Location:
    NH
    First Name:
    David
    Truck Year:
    1976
    Truck Model:
    k20
    Engine Size:
    6.5
    Asian garbage is poisoning the supply chain because it's cheap from currency warfare and there are limited import duties from the permanent "most favored nation status". Not all of the Asian manufactured goods are cheap crap. However there are too many that are to sift em out of the massive amounts of complete garbage. The Asians and Indians will lie to non Asian and non Indian customers because that's OK by their social and moral codes. What they sell inside their country and what they ship to the Laowai, Firangi, etc. are often very different products.
    My company tried the China/India Manufacturing game. When you find a good manufacturer... You have to ride them like a $2 whore to maintain a quality product. Our defects climbed into the 25-30% range vs the 0.2% from the American or Canadian Manufacturers. We rapidly came to the conclusion that the cheap price was not a real money saver.

    The Asians make some of the worst electric motors out there. Same deal with starters and alternators. Complete trash. The bearing pockets in the Asian housing on a 12SI I pulled off my cousins Cutlass were not machined such that the armature shaft would spin perpendicular to the belt. It was chewing up belts with fair regularity. The Borg wouldn't replace it under the "lifetime Warranty" because it tested OK electrically and the shaft spun smoothly. I added some sand to the bearings then re-installed and ran it for a few minutes to destroy the bearings and the housings then took it back... "Not sure how it happened but the bearings are toast as you can plainly see."
    The moral of the story is hang onto your original electric motors, starters, and alternators. You're miles ahead to get them re-built by a good local outfit. Barring a shorted armature... A competent electric motor shop can re-work your old window motors so they are better than new. They need to be douched out to remove all the oxidized petroleum grease, dirt, spiders, ants, ground up carbon brush, etc. Then proceed to check level and polish the commutators, replace the carbon brushes, and load the bushings and fresh felts with fresh modern synthetic motor lubricant.

    Enough off topic ranting. Look in and at the box. If it says made in CHINA or made in INDIA or even Hecho en Mexico walk away.
     
    Last edited: Jan 1, 2018
    mavtricks71 likes this.
  10. hatzie

    hatzie Full Access Member

    Age:
    52
    Posts:
    557
    Likes Received:
    385
    Joined:
    Dec 6, 2011
    Location:
    NH
    First Name:
    David
    Truck Year:
    1976
    Truck Model:
    k20
    Engine Size:
    6.5
    If the 75-80 wiring is in good condition with a dead six port solenoid valve you can build a fairly short harness with a pair of Bosch Automotive type SPDT Mini ISO relays to handle the motor direction switching.
    I mounted the relays on the firewall inside the cab.
    Spray the socket terminals down with Silicone Oil like Wurth HHS or CR battery terminal protectant and make sure the wires are pointed straight down with the heads of the relays pointed straight up to keep any water out of em. I also hose down the valve connectors and an other exposed connectors with the same to cut down on corrosion.
    You could use Metripak 630 Sealed Mini ISO relays like the F-Body cars but the relays and sockets cost more than the $3 Bosch relays.

    Here's a schematic and parts list for what I built for use on three K30 79 & 80 plow trucks.
    [​IMG]
     
    Last edited: Jan 1, 2018
    Dougnsalem likes this.
  11. Dougnsalem

    Dougnsalem Full Access Member

    Posts:
    1,147
    Likes Received:
    1,301
    Joined:
    Jan 13, 2018
    Location:
    .
    First Name:
    .
    Truck Year:
    .
    Truck Model:
    .
    Engine Size:
    .
    .
     
    Last edited: Jan 26, 2018

Share This Page