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Fuel sender puzzle

Discussion in 'Off Topic' started by Archeress, May 24, 2013.

  1. Archeress

    Archeress Guest

    to all the kombi sparkies out there...i am stumped..(not difficult to do these days).

    Whilst my engine and gearbox were out on my reputable mechanics floor i asked for the fuel sender to be changed. Seeing as it was dodgy and played up a lot.

    He installed a brand new sender (from czechoslovakia) Now my guage needle only goes up as far as the first notch..That little off yellow block. Indicating i have 10 litres or thereabouts in my tank. I put 40 more litres in giving me a total of around 45 litres...needle does not move off the 10 lliterish mark. Giving me the sh**s. I had it explained to me that the resistor behind my guage may not be now the right one to match the sender. We cant change the sender unit..i dont have the money for that. (oh the sender was tested in a workshop and yes it works.). so...do i need to get an appropriate resistor unit?. or......anything?. why does my needle rise about 8 mm but no more?. lol..thats all i got.....anyone?.
     
  2. Archeress

    Archeress Guest

    or in other words....seeing as a new sender was installed does that mean i need a new gauge?.
     
  3. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    It sounds like he didn't adjust the sender when fitting it.

    The resistor is called a "vibrator" and is for the voltage to the gauge.
     
  4. Archeress

    Archeress Guest

    hi phill..It was tested and he did adjust it..i recall him saying that. He said something about the ohms being different perhaps. Can i upgrade one of these resistors then ?
    to suit sender?.
     
  5. Archeress

    Archeress Guest

    i also recall "doc" doing a cut job on his rear parcel shelf and getting to sender that way..though it can be dangerous..just wondering if a new sender and gauge to match...sorry i am just rather confused.
     
  6. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    I have only replaced like for like. The ohms should not be different.

    What is the resistors? The sender is the resistor. The "resistor" on the back of the gauge is really a regulator (vibrator).
     
  7. Archeress

    Archeress Guest

    Regulator then..i just didnt want to call it a vibrator LOL.
     
  8. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    Why not?:lol:
     
  9. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    A normal check is to find the wire to the tank sender (brown) and just earth it briefly and watch your gauge go to full. That will check the gauge and vibrator.

    What year model?
     
  10. BrianK

    BrianK Well-Known Member

    Messages:
    8,043
    Location:
    Port Kennedy WA
    The fuel sender is oriented such that the float faces away from the filler opening. Maybe this has been put back in the opposite way. Use a little o-ring lubricant on the seal to help make it last longer and seal better.
     
  11. BrianK

    BrianK Well-Known Member

    Messages:
    8,043
    Location:
    Port Kennedy WA
    It should register 10-70 ohms as you sweep the float. If your old sender was shot don't be surprised if your fuel gauge still isn't working when you fill up for the first time. You may have a problem with the fuel gauge or voltage stabilizer attached to the back of the speedometer.
     
  12. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    There is a good section in the Bentley for faultfinding the fuel gauge.

    Section 4 13.2
     
  13. Ian 68

    Ian 68 New Member

    Messages:
    212
    Location:
    Qld
    Kelly,

    I had this problem when I put a bay tank in the Yoot.
    I bought VDO gauges and didn't buy the right sender unit, the sender unit and fuel gauge must have a matching Ohms rating or they will not work properly.

    I had the same symptoms as yours in that the gauge did work but did not who full etc...very very frustrating and took me a little while to work it out.
    Luckily I have a yoot so I could get to the tank easily ...do you still have the new sender unit paperwork ? Anyway of checking they match before you have to remove the tank etc ??
     
  14. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    Check the gauge first as it is a bugger of a job to get to the sender.
     
  15. BrianK

    BrianK Well-Known Member

    Messages:
    8,043
    Location:
    Port Kennedy WA

    Its a scarry job Phill if you have to cut the hole out.
     
  16. Red Kev

    Red Kev Member

    Messages:
    475
    Location:
    Moonee Beach
    I've just been through fitting a new (aftermarket) gauge, Kelly. Not sure where your existing fuel gauge is: in speedo, or a separate vdo gauge in dash or other location. If the latter, the gauge I bought after much research was a programmable gauge from Summit racing in the US. I did this because (a) I stupidly forgot to check the veracity of the sender when I had the engine and tank out :roll eyes: so I wasn't sure if it even worked; (b) I got lots of different info from lots of reputable sources as to what resistance range the sender worked in (10-70 ohms, as related here by Phil, was correct); (c) there was a third reason but I can't remember it (I need three reasons for kombi-related purchases to have the funds released by the finance minister. The third reason could have been a bit of a stretch.)

    The summit racing gauge let me select from four common resistance ranges. I don't have an in-speedo fuel gauge, hence the dash-mounted aftermarket version. If you're happy that your sender works (and has not been installed backwards as suggested by BrianK above, which is not unheard of), this external gauge might be a cheaper solution than pulling the engine to get at the tank/sender. Just a thought. I believe VDO and Autometer also make programmable gauges -- I couldn't track down a VDO one, and the Autometer, while much prettier, was a lot more expensive. My next option was to get a new speedo from Al at dasrestohaus with an in-speedo fuel gauge which is also programmable, but that was a bit more expensive and I couldn't come up with the requisite three reasons for the extra expense.

    But before you do any of that, do you have access to a multimeter? YOu should be able to test that the sender is working. Your mechanic did plug the sender wire into the sender unit, right? I seem to recall seeing a 'reading' on a fuel gauge even though the wire wasn't connected to the sender.
     
  17. Archeress

    Archeress Guest

    thanks everyone for all the comments..you have all given me foood for thought. I wont be getting the engine yanked out again..wont be cutting a hole in the parcel shelf either. however i will investigate the lubrication. the U.S summit gauge and also using a multimetre where i can. quick question...is it possible to see the sender on top of tank from any vantage point without removing or destroying anything?.
     
  18. Alpal

    Alpal Moderator Staff Member

    Messages:
    9,036
    Location:
    Melbourne Bend of Islands
    Some say you can remove the firewall panel between the engine ang tank without removing the engine. Not recommended by me! And you cannot see much anyway. You can measure the resistance at the sender wire on the rear of the gauge. If its between 10 and 73 ohm then the sender may be OK. Another check is to apply a resistance to the sender terminal of the gauge. Again 10, and 73 ohm should cause the gauge to read. 22.5 ohm is half.
    The vibrator/regulator is actually called a voltage regulator and, If I can remember correctly, it emits an average 4.2V.
     
  19. ttmck

    ttmck Super Moderator Staff Member

    Messages:
    2,771
    Location:
    Hallett Cove STH AUS
    Last edited: May 30, 2013
  20. syncro

    syncro Well-Known Member

    Messages:
    10,371
    Location:
    Southern Highlands
    The last section of Jim's page is the important bit for fault finding as it shows you the test for the gauge, sender and vibrator.
     

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