Mk2.5 fuel sender fault

Replaced both sender and instrument gauges panel and still have fuel gauge registering as half full or full. Low fuel level light also shows. Also have tried New earth to sender. Any advice would be most appreciated. Cheers

The warning light is controlled by the part of the instrument cluster with the odometer in it, have you tried changing the complete cluster or just the fuel gauge part? I’m struggling to link that to the gauge reading incorrectly though…

What happens if you ground the Brown/Black wire at the sender unit?

Changed cluster.

Had been working fine until I took car of road for suspension strip down. Took original sender out and was tested. Appeared to be ok. Offered tested sender and cluster at reasonable price so changed both. Made no difference. Thanks

Have you had the sender out of the tank, plugged in and operated it by hand?

Not that proficient at electrics. Could you give some guidance on grounding black\ Brown wire.

Yes. First thing I did. Did zero but returned to half full.

Returned to half full with the level arm still in it’s lowest position?

Food now…

Low fuel light as always displayed since problem started.

Did plug in New sender out of tank,same problem,so I assumed it was cluster.

Which colour wire did you run a new ground in from?

I did a simple earthing by placing wire on sender top to
adjacent metal body. What earths the sender unit normally?

It has an earth that it shares with the fuel pump, the black wires.

Does the engine run?

What’s the VIN?

Has anyone considered that there might only be half a tank of fuel in it.

Joke… sorry I couldnt resist

Not such a stupid question Keat63, it wouldn’t explain the fuel level light being on but I’m not really sure what the float is doing when the gauge is showing half full.

Hi, currently (after battery disconnected for 24 hours),sender now sitting on quarter full with ignition off. Disconnect sender stays at 1/4 full. Ignition on - returns to zero in guage. Reconnect at sender stays on zero. Ignition on returns to1/4 full. Cycle of events complete. I can now repeat with same sequence. Sender gives readings of 110 ohms - 05ohms. Ran grounding wire from sender to body. Checked for continuity ok. Low level light still shows but this could be a red herring.Thanks for any input. Engine was running fine but as developed overheat problem. Could they be related . Maybe shared ecu.

Do you realise that MX-5 fuel gauges still ‘read‘ with the ignition off. They don’t change until the ignition is switched back on again though.

If you manually operate the float with the sender connected but out the tank with the ignition on, does the gauge follow?

Thanks. Previously would return to zero when ignition switched of. As explained it now does not do this. If gauge still accurate, I can live with this. Have read in other posts that gauge does not always zero but confusing when my gauge did. Wonder what as changed.Still learning! Again thanks.

Hi sender currently in tank will remove later and have a play around .

What is the purpose of the metal bracket on the top of sender with square hole. It appears to have no use.