Moss Motors, Ltd

Hi......... can someone help?

 I have a 1990 Mini Cooper, carburation variety. This has the triple instrument binnacle, containing the Rev counter, speedo, water temperature and petrol gauge etc. The petrol gauge is not reading correctly. When the car is filled up the gauge reads full, but when the tank is about half full the gauge reads empty. {It is a 34 lt tank and takes about 17 lt to top it up again.} I have changed the petrol tank sender with no difference in readings. I have changed the petrol gauge, still not difference. It have checked the wiring and earthing.

 Looking at the wiring diagram, the only other component in the circuit is a voltage stabiliser. In my case this is 'built into' the instrument printed circuit board i.e. it is not the 'metal cube' variety that can be changed.

 Does anyone think this is the problem {the water temp gauge also reads low and the indicator flasher 'ticks' faster than 'normal'. Where can I get another printed circuit board?

 

Regards

 

Nick Cooke

Nick,

Your profile says -8 GMT, but your "accent" and use of terms says 0 GMT. Assuming that is so, I can't help you with where to get spares, but...Have you checked the running voltage of your alternator at the battery? It sounds like you may be overcharging to beat the band. Give it a try and repost. We'll go from there.

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Hey Nick,

The voltage stabilizer should just unplug from the c/b ? as said check the charging voltage! it should be around 13.2 ish. That fact your water gauge and indi's are suffering a little does seem to suggest the voltage stabilizer!

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Oz Cooper
Classic Mini Product Manager UK


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Nick and OzC,

Yes, the stabilizer may be a culprit here, but the reason I asked about charging voltage is the fast directional flashers. The flasher is not served by the stabilizer to the best of my knowledge. And, it (the voltage) could explain the rest of the symptoms. I'm quite curious on this one

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Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Hi all.........

 On my particular car {1990 Mini Cooper} the voltage stabiliser is definitely part of the PCB {not the 'tin can' type}. I have bought a new 'tin can' and will attemprt to wire into the circuit. As for the charging voltage, I will measue this and let you know.

 To motorbill66 ~ what do you race in the States? I am very involved with the Mini 7 Racing Club in the U.K. {Chairman}.

Nick

Follow up to fuel gauge 'saga'......

 The voltage stabiliser is part of the fuel gauge meter. If you look at the fuel gauge {a bi-metal type of instrument, like the temperature gauge} there is an additional bi-metal strip with a small {factory set} set of contacts. A coil {wrapped around the bi-metal strip} is connected 'across' the battery. Oscillation of the contact drops the votalge to a mean of about 10v. This feeds both the fuel gauge and the temperature gauge on the 'positive' side of each meter. The other 'side' of the meters are fed by a 'variable earth'. i.e. the tank sender in the case of the fuel gauge.

Saying this, I'm still no nearer finding my problem. I will check the voltage at the meter, at the battery, empty fuel tank and fill up checking readings etc. If nothing comes of that, I will have to live with it!

 Regards

 

Nick Cooke 

Hello Nick, I thought I might point you in the right direction with this one. I am afraid you are being just a touch too technical for this.

Basically just remove the sender and bend the float arm.

The things just dont work properly because of the shape of the tank. I have bent mine such that the arm only starts to move after I have covered about 100 miles or so. This then gets down to the empty mark when Ive still got about 50 or so miles left in the tank. It will probably take you a few goes to get it how you want it.

While the sender is out, just prove to yourself that it works by moving the float across its travel so that the fuel gauge goes from empty to full.

Good luck.

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Mini 40....its a wicked ride

Don't forget Ohms Law.  if the voltage is high then the flasher unit, basically a capacitor, will charge and discharge quicker  making the indicators seem fast.  On such a relatively low voltage as 12v even 1 or 2 volts increase will mean about a 18% increase in charge discharge times.   Hope that helps...

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Happiness is Clubman shaped...