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Sending unit removal question.

Discussion in 'The Garage' started by AntAZBlaz, Feb 1, 2005.

  1. AntAZBlaz

    AntAZBlaz 1/2 ton status

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    Ok I did my search but I couldn’t find exactly what I was looking for I have my 86 blazer that I’m doing a tank replacement on and I have dropped the tank down to where I can reach the sending unit on top of the tank. But I can’t figure out how to disconnect it. I put a long screw driver in between the hose connections and tried to turn it but it’s not moving. In my manual it mentions using two screw drivers to remove it. I cant see what’s going on to well because the tank is only dropping so far with all of that still connected so can some give me some information on the best way to get that sending unit off?



    The negative terminal is it supposed to pull free? Because I was pulling on it pretty hard with no give.



    King
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Remove the tank from the vehicle. You likely can't drop it far enough with things connected to it, to get the sender out...the sending unit has to be manuevered around because of the float...it doesn't just come straight out, and it is as tall as the tank is, so you will need some room.

    There are little metal tabs that stick up on a metal ring around the outer perimeter of the sending unit. You put the screwdriver against one, tap it, (which will move the ring a hair) then switch to the opposite side, and just keep it up that way.

    I believe its counterclockwise to remove the ring. You will see how it comes apart once you start it moving. Good idea to blow any dirt and dust away, as it will find its way into the tank once the sender comes loose.
     
  3. AntAZBlaz

    AntAZBlaz 1/2 ton status

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    OK so I need to disconnect all of the hoses to get that tank to drop and then remove the sending unit. I was hoping that I could remove that sender.



    I must be off a little because I thought a few of those lines were metal ones so how could I drop the tank down with them connected?



    But thanks for letting me know I would have wasted a lot of time trying to do the wrong thing.



    King
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    On carbed trucks, all the metal lines are joined to the fittings on the sender with rubber sections, all with little metal clamps that you release with pliers. Remove the fuel fill and "overflow" rubber sections from the fill neck on the truck, push them over the frame (towards the tank) and now you should be able to lower the tank (with a floor jack under it IMO) far enough to reach in/see the rubber hoses and clamps. Still a pain to pull the rubber lines off, but whatever you do, don't cut the one for the fuel fill...they are fairly pricey and in some locations hard to find.

    Don't forget to remove the ground wire and disconnect the fuel sender wire, or they will break when you drop the tank. The ground one is bolted to the frame somewhere (black wire) so remove it from the frame. Mine had a disconnect near the tank for the sender (pink) wire.

    All the hoses/lines ARE connected to the sender...it's all one piece, so you have to disconnect them to pull the sender out, even if you are able to access it without disconnecting them.

    Just easier to drop the tank so you can see what needs to happen. As you've found out, trying with the tank up is painful. :)
     
  5. surpip

    surpip 1 ton status

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    There is a total of 4 hoses plus 2 wires on the sending unit, 1big fill line, and the vent line, they are running together out the side of the tank,held on by hose clamps, than there are 2 metal lines they unbolt just like the brake lines, a ground wire, and the sending unit wire, 2 easy connectors.

    Make shure you get a wrench on both sides of the fuel lines if you dont there is a good chance you will ruin the lines on the sender
     
  6. spearchucker

    spearchucker 1/2 ton status

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    I'll just confirm that the cam ring on the sending unit goes counterclockwise to loosen. Also when I did mine I took a sharp knife and cut the glue/sealer that was holding the cam ring in place. And I also used a brass drift so there wouldn't be any sparks. When the cam ring was off I cleaned off all the loose dirt with a vacuum cleaner.
     
  7. AntAZBlaz

    AntAZBlaz 1/2 ton status

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    Thanks everyone, I got the fuel filler hose off and I ended up cutting off the rest of the hoses and just ended up spending 4 dollars to have them replaced. I’m going to throw the new tank up in the truck tonight.

     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Trick to get the hoses to go on easy under the truck, is to spray the fitting or inside of the hose with WD40. Can make it hard for you to grip, but allows them to slide on easier, which is a big help, especially on the ones that are harder to reach.
     
  9. SubYuman

    SubYuman 1/2 ton status

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    D@mn kids!!!

    About a year ago, I had to drop the tank because some of the neighborhood kids decided to put rocks, sand and leaves into one side of the streets gas tanks.
    I replaced the pump and screen, but when I put it all back together, there was no fuel level...read WAY past full. I handled the sender VERY carefully, but it still doesn't read correctly. When I fill the tank ($103 here in Hawaii), it moves but not the right way.Is there a fix or do I need to replace it? Does anyone have agood source forGMpartsthat won't charge me$200 plus shipping?
    ACDelco Part # 25178863 is the part #
     
  10. spearchucker

    spearchucker 1/2 ton status

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    The sending unit is just a rheostat and that may have been damaged by the debris. When you take the sending unit out look at the float arm. On the end of that is a thin brass (I think) tab that rides against a variable resistor. That brass tab may have been bent or got something stuck between it. Just clean it off or bend it back and you should be good to go. You should also check it with a multimeter when you're done. In one direction it should read 0 ohms and the other direction should be 90 ohms. I'm sure deayger will correct whatever my memory failed me on.
     
  11. dirtwarrior17

    dirtwarrior17 Banned

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    I did the same but inside and out the tank just to be safe... since i had no time issues i let it sit upside down for 3 days and then got the inside vaccumed out and had to drill a hole in the top of the tank for the inline pump wires then i jb welded them to the tank to keep them from getting frayed.
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    Vacuum cleaners and gas tanks --yipe!

    A gas station near my sisters house a family friend owns had hired a new kid the clean the shop,and to learn to fix cars--one day he helped the boss remove a gas tank from a chevy truck,while lowering it from the truck about a gallon of gas spilled out of the filler neck pipe--the boss told him to clean up the spilled gas,and went in the other room to answer the phone--a few minites later he heard the sound of the shop-vac running--he got about 1 foot from his chair when the overhead doors of the shop blew out,and the kid and the vacuum cleaner was 25ft away out in the parking lot!!-:yikes: :screwy: -it blew out all the windows in the office and some of the customers cars parked out front too!-it didnt burn too long though,so fire damage was minmal ,despite the big boom!-needless to say,that kid doesnt work there anymore!-(lucky he wasnt hurt bad or killed!)--:crazy:

    I know you said you let your tank air out a few days before you used the vacuum on the tank--good thinking!--but gas tanks can explode even afer a long time being empty,so be very careful if any of you try this!!:crazy:
     
  13. goldwing2000

    goldwing2000 Guest

    If it's reading full, you have an open in the circuit somewhere. Either the pink wire to the sender is open, the ground wire is open or the sender is faulty.
    Pull the pink wire and ground it to the frame. If the gauge goes empty, the pink wire is good. Reconnect the pink wire and check the black ground wire from the sender to the frame. Hook a jumper wire from the sender to ground. If it works properly, repair the ground wire.

    If it still doesn't work, pull the sender and check for internal broken wires or a sticking/missing float. Check the sender withn an ohmmeter. If the sender ends up being bad, replace it. I bought a new one from http://www.rockauto.com/ and got a decent deal.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Is going to be cheaper than GMPD I'm sure:

    gastanks.com

    Before replacing, test and try to repair though, going to have to pull the tank anyways if its not a wiring issue, and $100 is a lot to spend on something that can likely/hopefully be repaired in a few minutes time.

    You can always test your repair with the sender out of the tank anyways, so its not like you need to bolt the whole tank back up to see if you fixed it, if it is indeed a sending unit problem.
     

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