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Fuel Gauge and sender question

Discussion in 'Fuel System & Electrics' started by Garbon, Sep 21, 2010.

  1. Garbon

    Garbon Member

    Messages:
    68
    Location:
    Albany Creek, Brisbane
    Hi All

    My fuel gauge does not go beyond the F mark when I know it is full. It sits on top of the F mark on the gauge - is this normal? Other cars I have had go beyond the F mark when full...

    I have noticed that it moves back down to 1/2 very quickly as though there is a leak in the tank or something but there is not. So it seems like it is using alot of fuel on the first half of the tank... I fill it up, drive a bit and it has moved already...:wtf:

    Once at the 1/2 way mark it sems to take longer to drop between 1/2 and R

    Do most of you see the same thing? Is it due to the shape of the fuel tank and sender etc?

    Thanks!
     
  2. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,775
    Location:
    Penna, Hobart
    I reckon every one has a different story. If yours works all of the way, it is a lot better than a lot of folks.

    Anyhoo, the sender is mounted in the top of the tank and goes from almost horizontal level down in an arc to almost vertical. Depending on how the sender resistor is wound and the condition of the earth, the condition of the wiring to the dash, and the condition of the voltage regulator and gauge you could have a variable accuracy on the gauge. Only real way to check it is to drain the tank and then check the amount added to give you certain readings.

    Unlikely that you have a leak unless you smell it or see it on the ground, and I would be surprised if you were using more fuel in the top half of the tank. Just an illusion.

    Good luck

    Adrian
     
    David H and oldman like this.
  3. Mellow Yellow 74

    Mellow Yellow 74 Active Member

    Messages:
    842
    Location:
    Sydney
    Hi,

    It may just be an illusion but I agree the first half of the tank seems to go quick on the gauge. I have had some carby problems which have only recently been fixed so hopefully this will help things - I need to keep records of litres/km to work out the consumption to check this.

    It might also just be that the Kombi fuel tank is smaller than other new cars of a similar size such as a 4WD plus the fuel consumption of newer cars is better, so I am used to the gauge moving slower.
     
    Last edited: Sep 22, 2010
  4. ttmck

    ttmck Super Moderator Staff Member

    Messages:
    2,735
    Location:
    Hallett Cove STH AUS
  5. Garbon

    Garbon Member

    Messages:
    68
    Location:
    Albany Creek, Brisbane
    I'm not sure, will have to work it out next time I fill the tank

    It is 55L right?
     
  6. bolts

    bolts Member

    Messages:
    147
    Location:
    Bonbeach, Victoria
    It is the result of the geometry.

    The float travels through an arc where the vertical displacement is greater in the first half of travel than in the second half of travel.

    Hence the fuel gauge moves from full to half-full more quickly than from half-full to empty.
     
  7. saabman

    saabman Well-Known Member

    Messages:
    4,784
    Location:
    Goulburn
    If mine EVER reached F I would be happy :lol:
     
  8. Joeb88

    Joeb88 Member

    Messages:
    29
    Location:
    melbourne
    I got exactly same problem with mine on full tank first 1/2 went very quick and was questioning too if there was a leak but been told they are never perfect but gets you thinking if empty really means empty lol

    Does anyone have a rough idea on how much you should be getting on a tank for a bay camper to see if the old timer is thirsty :)
    cheers
     
  9. saabman

    saabman Well-Known Member

    Messages:
    4,784
    Location:
    Goulburn
    I have a 1800 bay - not a camper but fuly loaded with camping gear. I work on getting fuel every 300km.

    Economy wise Im using around 11.4 liters /100km
     
  10. TasDevil

    TasDevil New Member

    Messages:
    11
    Location:
    Hobart
    Hi guys

    I've recently bought a 1974 T2 Bay window pop top.
    The lady told me she gets roughly 100k per tank. I went north about 90k on sat and had to top up from about 1/4 full to get home.
    It seems to me either to be a small tank or the gauge reads incorrectly (though it does fluctuate between R and 1/4 when going up or down hill)
    can anyone tell me what size the tank is for this model and what sort of k's i should expect out of it?
    Seem to defeat the purpose if i need to refill every 100k or so.

    Cheers
     
  11. Barry

    Barry Well-Known Member

    Messages:
    3,396
    Location:
    Abbotsford NSW
    G’day

    A 74 has a 60 litre tank and you should get around 350 - 450kms per tank

    Approx 6 to 7 Km per L

    Heavy auto camper at the low and and an empty manual van at the top

    They are notorious for having dodgy fuel gauges.

    Do some searching for others experiences and fixes
     
  12. saabman

    saabman Well-Known Member

    Messages:
    4,784
    Location:
    Goulburn
    And if some one has blocked off the tank vents - It can suck the tank in and make it loose significant capacity as well.

    But as Barry said - fuel gauge could be dodgey.
    The fuel sender is the cause of most issues. Might read empty up till 1/4 of a tank then be ok for the remaining 3/4 , depends on where it’s broken.

    I’d fill her up record the odometer throw in a Jerry can of fuel and drive around till it stops and see how far you’ve gone.

    It can be a bit nerve wracking not knowing when your about to run out of fuel. I went for years with a dodger guage and just filled up every 300km and all was well. I replaced the guage and ran out of fuel ... (my tank was distorted so read wrong )
     
  13. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,775
    Location:
    Penna, Hobart
    The tanks shape doesn't automatically mean it is 60 litres usable, most have trouble getting 55 in from dead empty due to the filler being lower that the top of the tank when level, so closer to 50-55 litres and with a 2l around 12l/100km. An 1800 should be around 10-11 l/100Km. We used to have a survey on here somewhere that showed the averages for different setups taken from collective experience and they were close to these figures.

    Adrian
     
  14. TasDevil

    TasDevil New Member

    Messages:
    11
    Location:
    Hobart
    thanks for all the response. Had a feeling it was the gauge.
    Anyone know of anyone in Perth who can replace the sender for me?
    Is it worthwhile upgrading the gauge to be more reliable and if so what type is suggested
     
  15. tintop

    tintop Well-Known Member

    Messages:
    424
    Location:
    Canberra
    the sender is on top of the tank which is behind the engine...you either do it when the engine is out or cut a hole from above with a jigsaw.

    or just go by your odometer
     
  16. saabman

    saabman Well-Known Member

    Messages:
    4,784
    Location:
    Goulburn
    You can do it with the engine in (pull the carbies for more room)
    It’s not for the faint hearted and you need good dexterity but it can be done.

    Otherwise there is a vw specialist in Fremantle (no idea if they are any good I just noticed them as I drove past one day)
     
  17. chris taylor

    chris taylor Well-Known Member

    Messages:
    1,804
    Location:
    adelaide sth aust
    Hi Tasdevil .
    I have a 76 kombi,and had much the same problem as you, it could be a couple of things , when I took mine to be fixed they did both the sender and the gauge at the same time { AND from memory I think there was something else electrical in between, which had to sorted out as well }. some other member might know about this .Now is ok but certainly not 100% accurate but good enough for me , by rule of thumb fill up every 300 ks regardless and you will be ok.
     
    TasDevil likes this.
  18. TasDevil

    TasDevil New Member

    Messages:
    11
    Location:
    Hobart
    I also have an issue with 74 T2 accelerator stiff to depress. missus gets a sore ankle/foot on long drives due to stiff pedal.

    I've heard you can change the linkage out for a spherical bearing rod end which might alleviate help the problem but dont know much else about it
     
  19. Barry

    Barry Well-Known Member

    Messages:
    3,396
    Location:
    Abbotsford NSW
    Last edited: Dec 10, 2018
  20. Jerome

    Jerome Well-Known Member

    Messages:
    1,196
    Location:
    Mentone
    For years I did not have a working guage .
    Even did a lap of Australia without a working guage...just keep a log fill up every 300km.
    I still do that even after fixing the guage
    It's an easy fix if the engine is out.
    So suggest you wait till you need a new clutch or have to pull the engine out for something else.
     

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