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Another Fuel Gauge Issue - '98 Rover
https://www.ausmini.com/forums/viewtopic.php?f=2&t=85819		 Page 1 of 1
Author:  BKozan [ Mon May 26, 2014 4:02 pm ]
Post subject:  Another Fuel Gauge Issue - '98 Rover
So I've done my reading, but I'm yet to find anyone with a problem quite as bad as mine.

My fuel gauge "works", as it smoothly transitions from a half tank to an empty tank as I go along. But, it is waaaaaaay off, by at least a half tank. So it seems there are 3 options to fix this...

So where would you guys start troubleshooting? If the voltage stabiliser were bad, would it still seem to work nicely between half and empty? (And furthermore, does my '98 Rover even have this voltage regulator? I've read in some instances that my 3 dial, Japanese made gauge cluster has this stabiliser built in?)
I'd like to adjust the sender unit, but at more than half a tank is this too far to adjust it? I'm not sure what the range is on that adjustment screw. If I do this, what are the chances I'll be able to re-use the gasket? I'm really hoping this is the ticket, as it is easy and can be re-adjusted in the future should it play up again.

I know this is a common thread with Mini's, but as this is my daily driver I rely on the gauge quite a bit. I constantly log all of my fill-ups, and have resorted to doing the math and checking my odometer regularly to see when it's time for a fill up. Even so, every time I find myself stuck in traffic looking at a gauge that is well below the red mark, I begin to sweat!

Thanks guys,
Author:  carter [ Mon May 26, 2014 4:08 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
My dads riverboat he same I discovered after a trip to qld recently. The gauge would be on the red line I'd go to fill up and I could only put half a tank in.....will be interesting to see how people say to fix the problem.
Author:  Harley [ Mon May 26, 2014 4:10 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
The regulator is built into the fuel / temp gauge unit - same one powers both I think. It's been a while since I pulled one apart.

What exactly is it your gauge is doing? If it never gets to full when you full the car I'd adjust the float - if its still floating.
Author:  9YaTaH [ Mon May 26, 2014 4:22 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
If it were me...

Yep fiddle with the sender (if you can) with a known amount of fuel in the tank...the "fault" could be anything from the gauge, the sender/float to wiring/regulator...

I would try and get a little scientific and carefully apply a voltage to the gauge itself to find out what sort of voltage you need to show full (check what sort of voltage the sender is putting out first to get yourself in the ball park).

Once you know what the full scale deflection is of the gauge you could also maybe find another to check and to discount the gauge itself.
Author:  Harley [ Mon May 26, 2014 4:36 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
The gauge resistance should be 270 ohms empty, 67 ohms medium, and 15 ohms full.
Mine measures as 20-250 full to empty and gauge is fine, so being a little out is okay.
Author:  BKozan [ Mon May 26, 2014 5:10 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
Basically my gauge reads almost 3/4 when the tank is full, but very quickly drops to half after about 10km of driving. If I let it the gauge go to the very bottom (below the red mark, to where it actually "sits" with the car turned off) and fill it up I can only put in about 18 litres. If I've done my research correctly, I should have a 33 litre tank.

So it seems the best place to start is pulling out the sender unit and fiddling with it. What are the chances I will be able to re-use the gasket? Is it a crappy paper thing, or a sturdy rubber / cork deal? I'll check if the float has filled up with petrol, see how far I can adjust the screw, and then - as a last resort - start measuring gauge resistance. This is outside of my comfort zone, but the best way to rectify that is to start trying and learn along the way!

So how do I measure this resistance Harley? Grab a voltmeter and put it on either side of the gauge pickups itself (printed circuit board)?
Author:  Harley [ Mon May 26, 2014 5:21 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
Just get a resistance meter and connect it to the fuel sender directly. Make a hook out of a coat hanger and lift the sender up and down.
Author:  minijcar [ Mon May 26, 2014 6:30 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
:D :D :D :D :D
It make me laugh when i read what some people suggest or think.
Almost Everything previously posted to some extent is wrong.
It is possible that the float has fuel in it but otherwise :D
Don't try to adjust the sender as there is no adjustment.
250-19 are the parameters. Have been since September 1964.
If the pointer is resting abnormally low with the ignition off then the span of the gauge is out.
If not the output of the regulator may be low ; this does not happen often.
Generally the regs when faulty allow 12 volts to flow which makes the gauge read high. Obviously not your problem
It is not possible to measure the output of the reg with a multimeter accurately.

As a first step Fill the tank up and measure with the sender disconnected between the terminal on the sender and the body. You should get 19 ohms.
Author:  Harley [ Mon May 26, 2014 6:42 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
minijcar wrote:
250-19 are the parameters. Have been since September 1964.


Changed again in 92 to the 270-15. it's because the arm was changed to clear the fuel pump in the EFI tanks. The fact that I got 20-250 in mine was a fluke, cause I've had 270-15 before.
Author:  KLAS [ Tue May 27, 2014 1:24 am ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
there was a bulletin regarding fuel senders fitted from the factory beeing way out of spec
gives full instructions how to adjust them. there is a screw at the newer senders to adjust the arm
i only know the german one online, but i'm sure you can find the english version http://allbrit.de/downloads/BULLETINS/Tankanzeige.pdf

edit: BTW i build a small gauge tester. basicly just 3 resistors you can connect in place of the sender. you need 270 ohms for empty, 67 ohms for half full, and 15 ohms for full. quite handy for checking if the needle will show right.
Author:  9YaTaH [ Tue May 27, 2014 7:00 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
minijcar wrote:
:D :D :D :D :D
It make me laugh when i read what some people suggest or think.
Almost Everything previously posted to some extent is wrong.
It is possible that the float has fuel in it but otherwise :D
Don't try to adjust the sender as there is no adjustment.
250-19 are the parameters. Have been since September 1964.
If the pointer is resting abnormally low with the ignition off then the span of the gauge is out.
If not the output of the regulator may be low ; this does not happen often.
Generally the regs when faulty allow 12 volts to flow which makes the gauge read high. Obviously not your problem
It is not possible to measure the output of the reg with a multimeter accurately.

As a first step Fill the tank up and measure with the sender disconnected between the terminal on the sender and the body. You should get 19 ohms.


So you can't bend the float arm?

250-19 are the parameters. Have been since September 1964...and as you would know, wound resistances can drift high over time...

If the pointer is resting abnormally low with the ignition off then the span of the gauge is out....span? do you mean the calibration? The pointer may have moved or been bent?

It is not possible to measure the output of the reg with a multimeter accurately...why?
Author:  BKozan [ Mon Jun 02, 2014 11:47 am ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
Well, I opened her up this weekend and for anyone reading in the future, here is what I found.

First, the gasket that seals this up is sturdy rubber, and should last a lifetime. Second, the resistance on my sender unit was from 13 - 290, slightly out of spec. This means that the readings on the gauge will never be 100% accurate.

However, there was most certainly an adjustment on mine, which looks different from any of the photos I've seen posted so far. You can see the set screw attached to the float arm. With some careful adjustment, and a bit of trial and error, I have been able to get the gauge to be perty darn close on the empty reading. However, the full reading is still quite far off.
Image

On a side note, when I removed the sender I found this little round rubber grommet just hanging out near the top of the arm. I couldn't come up with any reasonable use for it, other than possibly some sort of float retention, but that didn't seem likely. I removed it, but am curious if anyone knows what it is for.
Image

As usual, thanks for all the help guys!
Author:  Harley [ Mon Jun 02, 2014 12:32 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
The black ring is supposed to go around the float, like in this image:

Image

It's only there as a bumper for when the sender gets to the top or bottom of the tank so that the plastic doesn't rub through.
Lots of them end up further down the arm like yours though.
Author:  MiniBob [ Mon Jun 02, 2014 3:56 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
There is another thread on here somewhere, I printed it off, about how to use the adjusting screw.
I only discovered it after bending the arm on mine twice :oops:

Is something I intend to fix as it now reads empty when it isn't.
Then I ignore it....... then I forget..............then I run out of fuel :P
Author:  BKozan [ Mon Jun 02, 2014 4:38 pm ]
Post subject:  Re: Another Fuel Gauge Issue - '98 Rover
I've always been a motorbike rider, so I have a knack for fuel / distance calculations and keeping an eye on the odo. It was to my dismay when I finally had a fuel gauge to look at - but it wasn't usable!! I've yet to run out of fuel, as my calculations are usually pretty accurate - but without a tripmeter it is a PITA. I am so glad to have it fixed! :D
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