Fuel Gauge Not Functioning Properly
Discussion
Just got my new (to me) m400 and have discovered a host of things that need to be addressed. One of the more urgent things is the fuel gauge. When the car is off, the fuel gauge reads 0 (empty). However, when the car is turned on, the fuel gauge immediately jumps to 1+ (extra full). When I took delivery of the car off the transport truck, I noticed to full gas reading and thought to myself - my, how considerate that they filled the tank prior to shipping it. So I drove it around for a day but noticed that the fuel gauge never moved. So I'm thinking that this car either as a 490 gallon tank and that it just hasn't used much fuel or the gauge is broken. Being more suspicious of the latter, and worried that I might be running on fumes, I went to ye olde friendly fuel refilling depot and lo and behold she sucked up 13+ gallons of fuel! BTW, what is the capacity of the fuel tank; how close to fumes was I?
If I had to guess, there are just 3 components to this system. 1) fuel level sensor 2) wiring between sensor and gauge and 3) gauge. Is there anything else? If I had to guess, I'd guess its the sensor that is bad. Has anyone else run across this? What is the troubleshooting algorithm I should follow to diagnosis and correct this?
Thanks,
David
If I had to guess, there are just 3 components to this system. 1) fuel level sensor 2) wiring between sensor and gauge and 3) gauge. Is there anything else? If I had to guess, I'd guess its the sensor that is bad. Has anyone else run across this? What is the troubleshooting algorithm I should follow to diagnosis and correct this?
Thanks,
David
Makes me long for a lift!
Catch-22: I assume you'd want to fuel tank empty (or nearly so) before dropping it (weight plus needing to work with it). But with a non-functioning gauge, you have no idea how much fuel is left in there. So you drive it and hopefully don't run out of gas!
It appears there are two wires that are on top of the tank that are attached to two spade plugs there. The one attached to the plug towards the front of the car is brown and the one attached to the plug towards the rear of the car is white/green. Is there any sort of polarity associated with these wires? Could they just be reversed? Or is it just a resistance output of some sort? Does anyone know the relevant reading range of this sensor?
I did find the connector for that wire. It was connected. And the wiring seemed to be intact from the sensor, through the connector, up to a point where it seems to go under/behind the fuel tank again. Wasn't able to trace it farther back.
Catch-22: I assume you'd want to fuel tank empty (or nearly so) before dropping it (weight plus needing to work with it). But with a non-functioning gauge, you have no idea how much fuel is left in there. So you drive it and hopefully don't run out of gas!
It appears there are two wires that are on top of the tank that are attached to two spade plugs there. The one attached to the plug towards the front of the car is brown and the one attached to the plug towards the rear of the car is white/green. Is there any sort of polarity associated with these wires? Could they just be reversed? Or is it just a resistance output of some sort? Does anyone know the relevant reading range of this sensor?
I did find the connector for that wire. It was connected. And the wiring seemed to be intact from the sensor, through the connector, up to a point where it seems to go under/behind the fuel tank again. Wasn't able to trace it farther back.
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