Fuel gauge readings, adjusting

"My fuel gauge only reads 3/4 when the tank is full and goes to less than empty when the tank is almost dry. Is there any way of adjusting/calibrating this aside from taking the sensor from the tank and bending the arm slightly."

If it is the clubman type ( behind steering wheel) then yes it is possible to adjust. My method...

first, fill the tank to full.switch off the ignition. next, remove dial pod i.e... pull the black plastic surround towards you gently but firmly until it releases from the clips. remove 1 (non tacho/revcounter type) or 2 screw bolts on top of white plastic surround. remove 1 screw bolt on each side of white plastic surround. reach behind pod assembly and remove the speedo cable, difficult as you have to press a release catch towards the centre of the cable end where it enters the speedo unit, and pull out at the same time. persist and it will come out. now you should be able to move the pod easily, leaving the wire connections in place ( pull the loom towards you to free up extra room) now remove the glass/plastic in front of the fuel gauge assembly, this is clipped in the case of the glass type (beware, the clips are not attached and fall off when removed). later model gauges have access to the adjusters from the front, older model gauges have to be removed.jump next section if you have newer type.

You should now see the black metal plate that has the fuel and temp diagrams on it, this is held in by small screws ( 3 usually ) remove these to gain access to the gauges. remove the screw holding the gauge in the holder from the rear of the pod ( double check you have switched off the ignition) now the gauge is free to be removed and adjusted! to adjust. there are 2 small slots for a screwdriver to be inserted, one moves the needle to the right/left, and one moves the needle range. the older type are very stiff to move and require a good fitting screwdriver. first adjust the needle position to point to empty i.e. bottom of the redline mark.

Now for OLDER models, apply the gauge to the rear of the pod on the plastic pcb ( circuitry) into the holes that it was screwed to, making certain that the redline mark is towards the bottom of the pod/the voltage regulator metal box. switch on the ignition ( re-adjust the position of the gauge so that the screw ends touch the copper connections )and note the position of the needle and which way it needs adjusting. switch off the ignition, and adjust the needle (with the screw slot that you haven't used yet) recheck the adjustment by switching the ignition on again and applying the gauge to the copper contacts. redo until the needle indicates top of 'full' line. now switch off, and check that the needle returns to empty as adjusted previously, if not, repeat adjustments by trial and error until both are correct.

For NEWER models there is no need to remove the gauge from the pod just remove the clear plastic from the front and the metal plate to gain access to the adjusters.now it is a simple matter of adjusting the 'empty' needle position and when satisfied, switch on the ignition, and adjust the 'full' needle position. (as per OLDER model instructions) when satisfied, switch off the ignition and check the empty position. repeat until both positions are correct. it is harder to explain than do! but also very satisfying.

Retro-fit fuel gauges, power source & calibration

A reply from Peter Kay ( An ERA Turbo owner) to a question I asked about using a seperate 52mm Smiths fuel guage instead of the gauge built into the 2 clock binnacle

POWER SOURCES: As you are aware, the ERA is fitted with six 52mm gauges, including a Smiths fuel gauge, the remaining five being made by VDO. From the circuit diagram, I see that they are all powered directly from the ignition switched positive supply rail from the battery and are, therefore, at approximately 12V (un-stabilised). I do not believe that the electric powered oil pressure gauge, or the fuel gauge are stabilised internally, just that they are thermocouple type instruments that are very slow to read, and do not respond to rapid changes in supply or input signal.

CALIBRATING: Regarding your previous query, concerning calibration of the fuel gauge. In my youthful past I had an obsession that demanded that I must know exactly how much fuel I had! To this end I always calibrated the gauge as follows. Firstly run the tank almost dry. Withdraw the tank sender from the tank and, whilst ensuring that the float is in fact floating in the residual petrol when refitted, bend the float arm, as necessary, to give an `Empty' reading on the Fuel Gauge when the unit is is in place and the engine is set at a fast idle, sufficient to give a full alternator/dynamo output. Stop the engine. Remove the fuel gauge, then remove the glass from the scale. Using matt black paint, carefully obliterate fuel level markings from the gauge, as necessary, then refit the gauge loosely. After warning the pump attendant of your intention, fill the car in 1 gallon* steps whilst the engine is running at fast idle, marking the needle position with pencil at each gallon. With the car now back at base, Use white Letteraset, or similar `rub down' lettering, to cover each pencil mark with a suitable line. Add any additional numbers or wording required. Refit dial glass, then secure gauge in place. A word of caution. If using a gauge from a different vehicle, then the gauge may be incompatible with the original sender unit. An initial test to establish if it reads Full scale when 12V is applied or grounded, depending on meter type, or reads Empty in the reverse condition, will establish if it can be utilised. I always adjusted the arm to read correctly at Empty and calibrated it from there as not only is this easier to do than draining a gallon at a time from a full tank, but it's the bottom end that you are normally interested in!

There are ways of adjusting the meter movement to read correctly at both ends, but these involve delicate physical adjustment to the meter mechanism, and, in my opinion, should not to be undertaken without sufficient skill and knowledge.

Pete Kay (http://www.eraturbo.com)

*or 5 litre increments if you are metricated!

This section Added 18 September 2004

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