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Motec fuel level

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hello everyone,

i have wired the fuel indicator through an m800 motec ecu, calbirated it in a user channel. But i am facing an issue that the volt keeps changing and i keep getting the wrong readying when i fit the indicator intake. What can be the cause? Should it be wired through 5 volt?

Your description of the problem isn't clear enough to understand what is happening. Why don't you provide some details about the fuel level sensor, and exactly how you have it wired. How did you calibrate the user channel and what does the calibration look like?

How did you determine how the sensor worked? Did you measure voltages when it's connected to the factory dash/ecu? What do they look like with a full (and empty) fuel tank? If the sensor is a resistive type -- with the factory wiring disconnected, what is the resistance when the fuel tank is full (and empty)?

The M800 can accept 0-15v signals on all the Analog Voltage and Analog Temp input.

Hello david,

the fuel level sensor basically has 2 wires that makes the sensor work, 1 earth wire that goes directly to the car's body and the other i wired to the AT channel of the ecu, i have do a custom calibration within the channel 0% read voltage value and 100% read voltage value, it worked perfectly when it was out of the fuel tank i even kept it in a water tank and it was working perfectly. The problem is when i put the sensor back in the fuel tank the voltages starts changing, when i drive the car the voltage changes even more ( decreases ) when i read the voltage value in the AT channel. Basically the % readying of the tank level as i start moving the sensor is perfect when it is outside the fuel tank when i put it back in the tank it reads -50% when it should read 95-100%. Voltage values goes from 0.080 up to 0.500 when out of tank, when car is runing and the sensor is in tank, the voltage value increases

So, do you think the sensor reads differently in Gasoline and Water? Or do you think there is something with grounding the body of the sensor when installed in the tank?

The sensor is only connected to the M800 right? Not to a dash fuel gauge as well (that could be the cause of an additional voltage pullup when the ignition is turned on).

Certainly a perplexing problem. Good Luck!

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