Low Fuel Level Sensor






This sensor is an optical low fuel sensor.  This sensor was carefully chosen to monitor aircraft fuel level.  It works great in the harsh environment of the fuel tank area and has a proven track record. The output is high when the sensor is in the air, low when in liquid. Please check with us to see a list of products that utilize this sensor.  The sensor comes with an appropriate nut and washer.  The sensor threads are 1/4 NPT.  The leads are about 5" long.



The optical fuel sensor is a non-contact sensor mounted in a single hole in the fuel tank.  It operates by bouncing a beam of light into the sensors lens.  If it is reflected back into the sensor, there is no liquid present.  If it is not reflected back, it is dissipated into the liquid media.  The sensor output is pulled down, or activated.  Lots of people ask if it works in a "T" fitting instead of mounting it in the fuel tank area, YES!  You just need to allow enough space so the tip of the sensor is away from the wall of the fitting. 



The sensor needs to be mounted horizontally or vertically (pointing up only) so that a drop of fuel does not accumulate on the tip of the sensor, otherwise it will still sense it is full of fuel. 



Using a "small amount" of "Fuel Lube" on the threads ONLY, it is to be screwed into a 1/4 NPT female fitting.  "Fuel Lube" should guarantee no leaks.  Sensor will malfunction if "Fuel Lube" is contacting the sensor tip.


DO NOT over torque!!   (13.26 in.-lbs. (1.5Nm)) Max.  It is NOT important that the sensor hex nut bottom out on the female fitting.


After installing the sensor, we recommend using a small amount of "Pro-Seal" or another brand of fuel tank sealant to help secure the sensor in place. Applying a small bead around the outside of the sensor should guarantee it won't back out, and may also inhibit future leaks from forming. This suggestion is just a bit of extra insurance.


Here is an AE Sensor ONLY spec. sheet that you may print.

Low Fuel Sensor Spec Sheet


See how to install the sensor.

Sensor Installation


NOTE:   MOST automotive and aircraft BUS voltages are NOT guaranteed to remain below 15.4Vdc.


This sensor cannot be operated with a higher voltage than 15.4Vdc!  It is for this reason that you MUST connect the power to the sensor to a lower guaranteed voltage.  Not to worry, it is pretty easy to remedy this.    You can use a 12V regulator like the LM7812 or LM78L12.  You can get these most anywhere.  This power source is regulated and will most likely not go above 15.4V.


You can even use a Zener diode in series with the power lead going to the red wire of the sensor to lower the voltage from a higher regulated voltage source.  The regulated source and the series Zener voltage value must also regulate the sensor voltage so as to guarantee it will not go above 15.4V. 


Also, DO NOT OVER TORQUE when installing it.

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Model: Low Fuel Sensor ONLY, (LFSensor)   $67.50

(Sensor operates from +4.5V to +15.4V.)

(Aircraft bus voltage is typically higher than +12V and should NOT be used to power the sensor directly.  See above warnings.)


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