11 replies to this topic

[NLinPEN]

I am not sure whether this issue is specific to the SPi/MPi cars. But because my Mini is a Japanese (JDM) one am I posting it here.

The issue is that the fuel gauge is not indicating correctly. When the tank is fuel it reads at around 3/4 full. When the gauge reads empty there is still quite some fuel in the tank. So I think there is an offset between the amount of fuel in the tank and what is indicated on the gauge. Is this something that can be adjusted? If so, how do I do that?

I was looking at the wiring diagram but couldn't find a clear indication. Is the fuel gauge directly connected to the battery, or should there be a voltage regulator in the circuit? If so, what should its output voltage be?

 

[slidehammer]

I would check the connections on the fuel gauge sender unit on the tank and if they are clean you can remove the sender unit (make sure the tank is low in fuel) and bend the arm to adjust the gauge reading. I had an issue with the fuel gauge reading erratically and that turned out to be the voltage stabilizer n the back of the instrument panel playing up once change it returned to normal.

[slidehammer]

Also the instrument stabiliser should output a voltage of around 10 volts

[Quinlan minor]

I am not sure whether this issue is specific to the SPi/MPi cars. But because my Mini is a Japanese (JDM) one am I posting it here.

The issue is that the fuel gauge is not indicating correctly. When the tank is fuel it reads at around 3/4 full. When the gauge reads empty there is still quite some fuel in the tank. So I think there is an offset between the amount of fuel in the tank and what is indicated on the gauge. Is this something that can be adjusted? If so, how do I do that?

I was looking at the wiring diagram but couldn't find a clear indication. Is the fuel gauge directly connected to the battery, or should there be a voltage regulator in the circuit? If so, what should its output voltage be?

The Mini is a whole lot less high tech than that!

Buy one of these: https://www.minispar...vel-sender-unit

Run the tank until it's as near to empty as you can get it. ( if you want to be super fussy, siphon the remaining petrol out of the tank via the sender hole.) 

Undo the petrol tank sender, carefully bend the float end of the arm up a bit.

Replace the sender and check the indication on the gauge. If it's still above 'Empty', pull the sender out and bend it a little more and re-check.

When you're happy with the reading, replace the gasket and you're good to go.

Edited by Quinlan minor, 28 February 2025 - 12:41 PM.

[NLinPEN]

Thank you both for your replies. I shall unplug the connector at the sender unit and measure the open voltage coming from the gauge. This should be 10 Volts if the voltage stabiliser is working properly.

Bending the sender unit is indeed a low-tech and simple fix (after draining the fuel to avoid a mess ...).

[NLinPEN]

I had not been able to make more progress on this topic until today. I did some electrical measurements but found unexpected results. Which made me stop and crosscheck with the community here. I'm not sure if everything is as it is supposed to be, or that there's something wrong.

(*) At first I measured the voltage on the connectors at the sender unit. I expected to measure a stable voltage, but it wasn't stable. It was fluctuating between zero and about 4~5 Volts. All kind of random values appeared on my multi meter. Unfortunately do I not have an oscilloscope to see what's going on.

(*) I then disconnected the cable that connects the sender unit to the gauge. When this cable is floating the gauge indicates below E (empty). When I short circuit the connector to ground the gauge indicates more than F (full). This is what I would expect, no surprises here. With the connector off was I able to measure the resistance of the sender unit. With the current fuel level is it about 42 Ohms.

(*) However, when measuring the open voltage on the cable I see again all kind of random values, fluctuating between zero and about 10 V. When I short circuit this wire to ground via a current meter I see that it is switching between zero and 0.29 Amp. Almost in a 1 second on, 1 second off manner.

 

So my question is: is it normal for the voltage stabilizer in the dashboard to show this kind of on/off switching behavior?

[68+86auto]

I had not been able to make more progress on this topic until today. I did some electrical measurements but found unexpected results. Which made me stop and crosscheck with the community here. I'm not sure if everything is as it is supposed to be, or that there's something wrong.

(*) At first I measured the voltage on the connectors at the sender unit. I expected to measure a stable voltage, but it wasn't stable. It was fluctuating between zero and about 4~5 Volts. All kind of random values appeared on my multi meter. Unfortunately do I not have an oscilloscope to see what's going on.

(*) I then disconnected the cable that connects the sender unit to the gauge. When this cable is floating the gauge indicates below E (empty). When I short circuit the connector to ground the gauge indicates more than F (full). This is what I would expect, no surprises here. With the connector off was I able to measure the resistance of the sender unit. With the current fuel level is it about 42 Ohms.

(*) However, when measuring the open voltage on the cable I see again all kind of random values, fluctuating between zero and about 10 V. When I short circuit this wire to ground via a current meter I see that it is switching between zero and 0.29 Amp. Almost in a 1 second on, 1 second off manner.

 

So my question is: is it normal for the voltage stabilizer in the dashboard to show this kind of on/off switching behavior?

 

Put the meter into a fixed range instead of auto ranging. If you have an issue then it's most likely to be the stabiliser or earth. There is no need to bend the arm and that will only make the gauge inaccurate.

Edited by 68+86auto, 06 March 2025 - 11:35 AM.

[NLinPEN]

 

 

 

Put the meter into a fixed range instead of auto ranging. If you have an issue then it's most likely to be the stabiliser or earth.

 

The meter was in a fixed range: in case of voltage I used the 20 V range, in case of current I used the 20 A range. So I can exclude that it was the multi meter switching between various ranges.

If the stabiliser is bad I need to disassemble the dashboard? I believe that it is located near the gauges on a printed circuit board?
 

[sonscar]

What you are seeing could be correct as I remember some regulators switched on and off rapidly to reduce the voltage.This may not be the case now though.I like an analogue meter for this type of work.Dinosaur Steve..

[timvandenboo]

Had a similair problem with my SPI. Had been checking wiring loom etc.. in the end turned out. The pin connecotor in the ECU plug did not connect with the male plug on the ECU unit. So there was a high internal resistant. Opened the connector and bended the pin slightly. Problem solved..... Maybe this is your problem also.

[orac69]

I have the exact same problem with my SPi.  With tank full gauge only reads 3/4.   When reading <0 I still have 15L or so in the tank.

 

I have replaced the sender with new from minispares, tested the resistance, wires etc, all good.  Im not sure I want to bend the arm. 

 

Thought id seen an article about tweaking the actual gauge ages ago - im going to look for it now but thought I would add a reply here first...

[Quinlan minor]

I have the exact same problem with my SPi.  With tank full gauge only reads 3/4.   When reading <0 I still have 15L or so in the tank.

 

I have replaced the sender with new from minispares, tested the resistance, wires etc, all good. 

I'm not sure I want to bend the arm. 

It's the best, and least expensive, way to get an accurate 'Empty' reading which is the one that matters.