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Hoping either a BMW guru or electrical guru can help with BMW fuel gauge problem.

Car ~ 1996 BMW Z3 roadster

This morning on the way to work I saw the fuel gauge simply drop to E; actually below E like it just quit working and the low fuel lamp was lit. I know it's not empty as I just filled it up yesterday. After getting to work I shut the engine off then turned the key back on. Fuel gauge read F as it should. On the way home tonight, I gauge read normal (F) for about 10 seconds then dropped to E again. I stopped a couple of times on the way home and it did the same thing each time. Starting the car, the gauge reads correctly but after maybe 10-15 seconds of driving, it goes back to E.

I wouldn't think a fuze as it'd either be working or not. Everything else seems to be working - dash lights, speedo, tach, temp, interior lamps, wipers, turn signals, etc. Any ideas?
 

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The cluster has three connectors, one is a 12 pin with three wires. The wires are black/yellow (signal wire to the fuel level sensor), black/red (signal wire the speed sensor on the differential) and brown/black (common ground for the two sensors. The black/yellow, fuel level, also connects to the "on board computer located in the console. I'm guessing it is for the fuel consumption calculation.

If the speedo is working you can expect the common ground back to the cluster is good. The connection at the tank sender may be the problem or possibly the sense wire connection at the cluster. I've never worked on a Z3 so I don't know how accessible the cluster connector and/or the tank sender.
 

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Dale
I think the early model had the fuel tank sender redesigned with better quality contact surfaces to prevent insulated connections which caused the symtoms you described.
The senders were replaced under warranty but probably not a recall.

Rene
66_Malibu
 
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