Fuel Sender bad ohms good gauge
08-09-2012, 10:32 AM
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Fuel Sender bad ohms good gauge
We have a problem trying to connect a data acquisition system to read the fuel sender off a 92' Civic.
When we read the fuel sending unit (floater) at the connector, the ohms readings are all over the place. Sometimes it shows the right ohms other times it shows crazy ohms like 100K ohms. Needless to say the data acquisition system jumps everywhere. The sender still inside the tank, we have not remove it.
So I would tend to think that the fuel sender is bad, but when you install the regular original gas gauge of the car, the gauge shows the correct gas level. Further crazy, after you use the regular gas gauge the sender starts working showing the correct ohms for a while until the car is off again, or if you wait long enough.
Any ideas on what could be happening here? Anyone has seen this behavior before?
Thanks,
When we read the fuel sending unit (floater) at the connector, the ohms readings are all over the place. Sometimes it shows the right ohms other times it shows crazy ohms like 100K ohms. Needless to say the data acquisition system jumps everywhere. The sender still inside the tank, we have not remove it.
So I would tend to think that the fuel sender is bad, but when you install the regular original gas gauge of the car, the gauge shows the correct gas level. Further crazy, after you use the regular gas gauge the sender starts working showing the correct ohms for a while until the car is off again, or if you wait long enough.
Any ideas on what could be happening here? Anyone has seen this behavior before?
Thanks,
08-09-2012, 06:50 PM
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Re: Fuel Sender bad ohms good gauge
Thanks for looking into this RonJ@HT. We took a closer look and actually cut the wires going into the sender so we had good access to the resistance measurement.
We are still not sure why we are not able to read the resistance from the sensor by itself while still in the tank. Nevertheless we are able to get the data acquisition to read the level of gas.
It seems as if there is a charging circuit that allows the circuit to work. I know there is nothing in there that would behave like that. We were seeing this with a tank pretty empty, once we added more gas into the tank, we got better readings.
Thanks for the help if you have other ideas I would love to hear them. It is my understanding that the fuel sender is just a regular potentiometer nothing else. Unless you get one of those fancy senders that measure the capacitance of the gas
We are still not sure why we are not able to read the resistance from the sensor by itself while still in the tank. Nevertheless we are able to get the data acquisition to read the level of gas.
It seems as if there is a charging circuit that allows the circuit to work. I know there is nothing in there that would behave like that. We were seeing this with a tank pretty empty, once we added more gas into the tank, we got better readings.
Thanks for the help if you have other ideas I would love to hear them. It is my understanding that the fuel sender is just a regular potentiometer nothing else. Unless you get one of those fancy senders that measure the capacitance of the gas
08-09-2012, 08:09 PM
#6
Re: Fuel Sender bad ohms good gauge
Post your diagram.
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