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Fuel Gauge


Best Answer Spider , 05 June 2020 - 10:09 PM

If you remove the gauge from the back of the Speedo (there's 2 screws holding it in), have a look at the face;-

 

d4Htl4t.jpg

 

just below the FULL, 1/2 and EMPTY marks you'll see 2 dots , they are fine and not easy to see, don't sweat it though if they have gone. On these particular gauges they line up close enough to the actual Face marks. On some of the 52 mm gauges, they don't.

 

If you flip the Gauge over, you'll see two Plugs on the back - these ones were cork, but some are rubber (and some are dust!)

 

JyNiY0k.jpg

 

Carefully pry the covers out and you'll see to slot 'headed' adjusters under them

 

A0ibJnV.jpg

 

As per the Photo above, one adjusts for the FULL Indication and the other for the EMPTY Indication.

 

Be aware, each does affect the other end. Ideally, if you have some time, it's best to do a full adjustment here.

 

To do this, you'll want a 33 Ohm 5 Watt Resistor, a 12 Volt DC Power Supply and take the Voltage Stabaliser from your Speedo.

 

Connect the 12 Volts to the Stabaliser with the -ve to the Case of it and the +ve to the B terminal.

 

With the Gauge NOT connected, adjust the 'EMPTY' adjuster until the Needle is on EMPTY. CAUTION:- The Adjusters only need a very small arc of movement.

 

Connect the -ve from the Power Supply to one terminal of the Gauge and the other Terminal of the Gauge to the 33 Ohm Resistor, the the other side of the Resistor to the I Terminal of the Stabaliser.

 

It will take around 1 - 2 minutes, for the Gauge to stabalise and it should now lay between the 2 dots at the Full end of the scale. Adjust the FULL adjuster until it does. Give it a good minute between adjustments to let the Gauge Stabalise.

 

Once that's done, disconnect the Gauge, give it a good 2 minutes and check again at the EMPTY mark.

 

You'll need to go back and forth between these 2 adjustments a few times because, as mentioned, adjusting at one end does have some impact on the other end too.

 

Assuming the Sender and the Voltage Stabaliser are good, it should now read correctly.

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#1 Vanman33

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Posted 05 June 2020 - 12:24 AM

Hi All,

 

I'm pretty sure my fuel gauge needs replacing but thought I'd ask for a second opinion.  Its a 1979 van with a centre speedo.  Ran out of fuel today with the fuel gauge reading just below quarter.  With the ignition off the gauge drops very slightly but doesn't drop to  empty.  If I earth the sender wire the gauge moves to full and usually get full range on the gauge apart from quarter tank and below.  Temperature gauge works fine so probably not the voltage stabiliser.  New sender fitted recently with new tank.  

 

Do I just bite the bullet and get another gauge? 

 

Thanks!



#2 Spider

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Posted 05 June 2020 - 12:55 AM

There is some adjustment in the gauge itself and from your description here, I'd say you would likely be able to sort this with doing just this.

 

I have to snap off some photos for a club article, so your post here is timely.



#3 Curley

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Posted 05 June 2020 - 12:58 AM

The fact that the gauge moves too full when you earth it out would suggest the gauge is good. Have you checked the new sender with a multimeter to see what you get? 



#4 Itsaminithing

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Posted 05 June 2020 - 01:00 AM

Take the sender unit out of the tank, re-attach the wires, turn on the ignition & then by moving the arm manually you can check that the needle moves in the range below 1/4 full.

If it does then the float is dragging slightly against the side of the tank & the arm needs to be bent fractionally (had this problem myself).... If it doesn't then the gauge might be at fault.

 



#5 Vanman33

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Posted 05 June 2020 - 07:38 AM

Thanks all.  I'd be very interested to know how the gauge can be adjusted.  

 

It isn't the sender as even with the sender disconnected the fuel gauge doesn't drop to empty.  

 

Thanks



#6 cal844

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Posted 05 June 2020 - 09:22 AM

Thanks all. I'd be very interested to know how the gauge can be adjusted.

It isn't the sender as even with the sender disconnected the fuel gauge doesn't drop to empty.

Thanks

The fuel sender can be adjusted, I'd bend the arm slightly so the float is more central in the tank, as it can snag the side of the tank.

Edited by cal844, 05 June 2020 - 09:22 AM.


#7 Quinlan minor

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Posted 05 June 2020 - 12:12 PM

 It isn't the sender as even with the sender disconnected the fuel gauge doesn't drop to empty. 

Does it go to 'E' when you turn the ignition off?



#8 Vanman33

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Posted 05 June 2020 - 05:47 PM

Thanks everyone.

To be absolutely clear, the fuel gauge never drops to empty and stays just above with the ignition off etc. I’ve also completely disconnected the gauge from the loom and that doesn’t work either.

When I fitted the new sender and tank it was fully calibrated both against the gauge and measuring the resistance. I did need to bend the arm slightly to ensure the full range was achieved.

It seems there is something now stopping he gauge fully returning to ‘E’. It did work fine

#9 Spider

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Posted 05 June 2020 - 10:09 PM   Best Answer

If you remove the gauge from the back of the Speedo (there's 2 screws holding it in), have a look at the face;-

 

d4Htl4t.jpg

 

just below the FULL, 1/2 and EMPTY marks you'll see 2 dots , they are fine and not easy to see, don't sweat it though if they have gone. On these particular gauges they line up close enough to the actual Face marks. On some of the 52 mm gauges, they don't.

 

If you flip the Gauge over, you'll see two Plugs on the back - these ones were cork, but some are rubber (and some are dust!)

 

JyNiY0k.jpg

 

Carefully pry the covers out and you'll see to slot 'headed' adjusters under them

 

A0ibJnV.jpg

 

As per the Photo above, one adjusts for the FULL Indication and the other for the EMPTY Indication.

 

Be aware, each does affect the other end. Ideally, if you have some time, it's best to do a full adjustment here.

 

To do this, you'll want a 33 Ohm 5 Watt Resistor, a 12 Volt DC Power Supply and take the Voltage Stabaliser from your Speedo.

 

Connect the 12 Volts to the Stabaliser with the -ve to the Case of it and the +ve to the B terminal.

 

With the Gauge NOT connected, adjust the 'EMPTY' adjuster until the Needle is on EMPTY. CAUTION:- The Adjusters only need a very small arc of movement.

 

Connect the -ve from the Power Supply to one terminal of the Gauge and the other Terminal of the Gauge to the 33 Ohm Resistor, the the other side of the Resistor to the I Terminal of the Stabaliser.

 

It will take around 1 - 2 minutes, for the Gauge to stabalise and it should now lay between the 2 dots at the Full end of the scale. Adjust the FULL adjuster until it does. Give it a good minute between adjustments to let the Gauge Stabalise.

 

Once that's done, disconnect the Gauge, give it a good 2 minutes and check again at the EMPTY mark.

 

You'll need to go back and forth between these 2 adjustments a few times because, as mentioned, adjusting at one end does have some impact on the other end too.

 

Assuming the Sender and the Voltage Stabaliser are good, it should now read correctly.



#10 Vanman33

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Posted 08 June 2020 - 12:01 AM

Moke Spider - Thank you so much for the detailed instructions on how to calibrate the fuel gauge.  I managed to sort it out today using your instructions but had to tweak both adjusters to get the empty reading correct.  I was fortunate in that having run out of fuel on Friday I knew the tank contained approximately 4 litres of fuel.

 

I managed to calibrate with the gauge in the car by removing the air filter (Conical K&N) and the speedo cable which gave me enough access to get to the gauge.  Probably not the right way to do it but the fuel gauge attachment screws were practically seized and removing the speedo is also a real pain.  Fortunately, having the K&N filter means there's no elbow on the carb giving more access once removed.  With hindsight I would have calibrated the gauge before I put it back in the can originally but hey - we live and learn!

 

Looking from behind the gauge with a torch I adjusted the right hand adjuster first with power off to move the needle to below empty, I then adjusted the left hand adjuster to move the needle down to just below the Empty position with power on.  Some may say that 4 litres is a big reserve but I'm happy to have the gauge reading empty with 4 litres remaining rather than the other way round as it was before.

 

Once adjusted I filled the tank and the gauge reads between 3/4 and full which probably means that my gauge is calibrated 1/8th tank out i.e reads lower but again I'm more than happy with this rather than reading 1/8th tank higher as it did before.  I think I could move the right hand adjuster slightly to remedy this but really don't want to mess with it any further for now.  It really is a fine adjustment as at one point I moved the right hand adjuster the wrong way and managed to get the fuel gauge to read 3/4 full with the power off!

 

Couple of additional points.  Firstly, a light application of penetrating spray helped on the adjusters as the gauge was quite corroded.  Secondly, use of different sized small flathead screwdrivers also helps as the adjusters were only partially visible behind the casing.  

 

Once again, thanks for the advice - I originally assumed those two openings were rivet heads!



#11 Spider

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Posted 08 June 2020 - 08:18 PM

Vanman, I'm glad this has largely resolved your issues here and for your feedback. Nice work.






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