Resistance for fuel sensor

[RJ Berg]

Hi, i would like to know if the is someone with knowledge on fuellevel sensor systems. Since my fuel tank only has a low fuel indicator i want to build one simple indicator i have however no room for a floater system due to the hole of tje indicator i have now. I would like to know if it is possible to place components that change resistance on contact with fuel. I'm no automotive expert so therefore my question.

 

[Diver300]

Hydrocarbon fuels don't conduct electricity, so you can't detect any resistance.

However it's possible to use a capacitive level sensor. The capacitance between a wire and the tank will depend on how much of the wire is in the fuel. If the tank is plastic, then you would have two parallel wires, one earthed and one as the sensor.

Measuring the small capacitance isn't easy. It needs an alternating voltage and the current flowing will be tiny.

Commercial sensors often have the wire inside a tube to increase the capacitance change. The wire can be hollow to save material if it needs to be a big diameter.

Have a look at:-
https://holykell.com/upload/file/1571283510.pdf

 

[shortbus=]

i have however no room for a floater system due to the hole of tje indicator i have now.

First, what is a *tje* indicator? What type of vehicle? Most fuel tanks have a built in rheostat type sender either swinging or sliding. I'd measure the voltage from the existing sender unit at the level of fuel you want as the low mark and then use a comparator circuit(using a LM393) to turn on the light at that point.

 

[Nigel Goodwin]

First, what is a *tje* indicator?

If you check your keyboard, the 'j' is immediately next to the 'h' - so the answer is obvious

 

[shortbus=]

If you check your keyboard, the 'j' is immediately next to the 'h' - so the answer is obvious

Some places in the world do have different names for things. I thought this may have been one of those.

 

[Diver300]

Did you use this sensor? How is it? https://holykell.com/upload/file/1571283510.pdf

I haven't used that sensor. I've used other capacitive level sensors but that was a long time ago.

 

[picbits]

Pressure transducer at the top of a pipe or tube would work in a vented tank scenario. We use this at work for sensing levels in tanks which we either can't or aren't allowed to fit senders to. The higher the fluid level, the more pressure read by the transducer. The only caveat is that you need to make sure the pipe to transducer fitting is 100% airtight.

 

[KeepItSimpleStupid]

Ultrasonic sensors?