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GM electricians I need help.

Discussion in 'The Hokey Ass Message Board' started by Roothawg, Sep 18, 2003.

  1. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Still working on that frickin m/h. I know what the problem is ..sort of.I was gonna just run a new wire and relay but I am afraid that it might be resistored down for some odd reason for the sender?

    It's a wiring problem, that much is for sure.
    Here is my question.

    I have 3 wires that go to the intank pump and sending unit.
    1.Pink
    2. Blk-chassis ground
    3. Tan/white stripe.

    I have 8.5 volts coming off of the pink wire, and none on the tan wire.

    I thought maybe the tan was a power wire but it is dead all the way to the front.

    Is the pink wire a power wire for the pump and sending unit as a whole? There is a 2 wire terminal in the top of the tank. Is the tan wire a return for the sending unit? It's about a 14 gauge wire.

    I have sechematics but they have no legends for the wire numbers.

    Thanks
    Root
     
  2. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    BTW, I swear to God, if I ever get this pig fixed it will never see this board again..... [​IMG]
     
  3. Gr8ballsofir
    Joined: Apr 21, 2001
    Posts: 768

    Gr8ballsofir
    Member

    where does the blk wire go?
     
  4. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Chassis ground
     

  5. Gr8ballsofir
    Joined: Apr 21, 2001
    Posts: 768

    Gr8ballsofir
    Member

    you said that... where?
     
  6. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    The tank has a 3 pronged weather connector and when it goes into the tank it has a ground soldered onto the pickup tube.
     
  7. DrJ
    Joined: Mar 3, 2001
    Posts: 9,419

    DrJ
    Member

    I'm not at all sure if your M/H is the same brand or not, but it sounds like you are talking about fuel delivery or pump fixing, and a friend told me about a fuel problem he had with one and it took about a year of fiddly-fuckin' around and asking questions before some guy at an RV service place said, "Did you check the inline valve?"
    Seems there is some kind of inline shut off valve on SOME of them beasts for emergencies or some such nonsense.
    Anyway, I'm pretty sure he said it was up in the right front wheel well area, follow the fuel lines to find it, obviously...and he just took it out and hooked the fuel line up without it.
    That fixed his.
     
  8. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Doc, naw mine is definately a wiring problem. I can hook up the pump on my battery charger and it pumps like a mofo. That is straight 12v. I can only get at best 8.4-8.5 V on the tank. I have chase it all the way to the fuseblock. still 8.4, it has 12V coming off the key. I am thinking I have a corroded butt splice or something. I was just gonna bypass the whole freakin loop but I am afraid I might smoke my sender if there is a reason it is 8V.
     
  9. Welp, the striped mo fo will be for the gauge and the pink is always "switched current" for G.M.'s. May I assume you're using a volt/ohm meter to get your readings? Then, I have to axe the same question about the ground. It seems it's quite possible you may have a questionable ground. Try grounding the DVOM to a known chassis ground and recheck voltage values. If you get an improved reading, your tank may not be enjoying a good ground, eh?
    While you're dicking around under there, ground the striped wire [NOT THE PINK WIRE!]and check the gauge reading. Is it reading empty? [or is IT all the way full?] If so,you should have a good gauge circuit. If not, try grounding to a known-good chassis ground and try again.
     
  10. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    The gauge works as adveritsed. I just think it may not be enough to jump start the pump. It won't even act like it is gonna try and come on.
     
  11. the guage is on its own wire at the tank, that wire is basically variable resistance to ground for the guage circuit and as such has no interconnection to the fuel pump wiring/circuit

    as for the fuel pump circuit, do as rocky said and double check your grounding first (of the tank)

    after determining that the ground is good, as i suspect it is, then move to the fire wall, there you will find usually 3 relays, one of which is the fuel pump relay. They can and do go bad, i have replaced quite a few.

    the relay itself has a schematic printed on it, and the spade terminals are numbered so it is easy to see where the power comes in, and which is the switch wire.

    check the battery power in terminal to determine that you have 12 volts, if not, trace back to find the fault.

    check to see if you have a full 12 volts to the switched terminal, if not then trace back from there.

    if you have good power to the relay and it still does not "click" then check the ground terminal wire to see if it has a good ground connection, if not correct that.

    if the ground is good, and you have 12 volts at the bat terminal, and 12 volts to the switched terminal.. then replace the relay.

    also you might look for a junction weatherhead connection along the frame, going back to the tank. i have seen those water proof connectors full of water and corrosion.

    also dont run the fuel pump dry, they die very quickly without the coolant of the gasoline.

    bob
     

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