FAQ About Fuel Monitoring Solution

UniGuard has been in vehicle fuel monitoring for 10 years now. Here we put a whole fuel monitoring solution and also common questions about it.

How does a accurate fuel monitoring system work? Please check

GPS fuel monitoring

How does ultrasonic fuel sensor work? Please check

Ultrasonic fuel level sensor

What are the differences of ultrasonic fuel sensor? Please check

Ultrasonic fuel sensor comparison

How does the fuel monitoring software work? Please check

Fuel Monitoring Videos

Common questions bout fuel monitoring

1 Does fuel level sensor send out fuel amount in Liter?

No. Fuel level sensor does not give out fuel amount directly. No matter it is ultrasonic fuel sensor or capacitive fuel sensor or any other type of fuel sensor, they measure the fuel level height in tank and the height unit is mm. However, most sensor does not give out height fuel to GPS. The height value will be transformed to a readable data by GPS tracker. The transformation from height to readable data is done per sensor protocol or algorithm. Each height matches only a readable data.

Take our ultrasonic fuel sensor for example:

0FA32(Hex)= 64050(Decimal) -> 64050 / 65535*1000 ≈ 977.3 mm

If the fuel level height is 977.3 mm, fuel sensor shall send 0FA32 to GPS tracker, GPS tracker sends 0FA32 to GPS tracking software, and the software shall display it as 64050 in decimal.

2 Does GPS tracker send out fuel amount in Liter?

No. Through above formula, we can know GPS tracker only receives and sends data. Its action does not connect with giving fuel amount in liter.

3 Does GPS tracking software display fuel amount in Liter?

YES. However, through above data, there is nothing about Liter is mentioned. This matters the formula of tracking software, which transforms the displayed data to liter.

1 At normal tracking software.

we need do fuel calibration, which is to fill fuel into tank and get a display data on tracking software.

Steps are as below by taking a 100L tank as an example

Tank is empty, there is a displayed value, say it 0. And tank fuel amount is 0L

Tank is 25% full, there is a displayed value, say it 25. And tank fuel amount is 25L.

Tank is 50% full, there is a displayed value, say it 50. And tank fuel amount is 50L.

Tank is 100% full, there is a display value, say it 100. And tank fuel amount is 100L

Then, we have to fill these data into the tracking software. Software will make a linear graph or report when fuel consumption happens.

This is a very old and complex way to calibrate the sensor. You can see example at fuel calibration.

2 With GPS51 Tracking platform

there is no need to do above fuel calibrations. We just need fill right tank dimension into an Excel. The Excel shall generate a series of data and upload these data to the tracking software. It is done. Please check here about how to use the Excel to do fuel calibration.

4 What is the difference between ultrasonic fuel sensor and capacitive fuel sensor?

Per feedback of our clients, the main difference is installation and price. To install capacitive fuel sensor, we need drill a hole in the tank top to fix the sensor. Ultrasonic fuel sensor is installed under the tank bottom and does not need tamper the tank. Ultrasonic fuel sensor price is a little higher but it can save the trouble of client’s regret of sensor installation and asking for compensation of the tank.

As for accuracy, in theory the ultrasonic fuel sensor is more accurate. However the accuracy is about height, and the unit is mm not liter. To change height to fuel amount, there are several steps. As long as the measure of height is stable, the fuel amount in GPS tracking software shall be right and accurate.

5 Can I use the vehicle self fuel sensor?

Some clients want to save the cost and trouble of fuel sensor installation. However, it is not a good fuel monitoring solution at all without external fuel sensor. A fuel monitoring solution without installation of external fuel sensor, it would be suggested.

1 Fuel theft control is not working. Vehicle own sensor does not work when engine is off, so it cannot detect fuel change at park state. Fuel theft mostly happens when vehicle is parked.

2 Vehicle self fuel sensor is not accurate. If the vehicle fuel sensor can give accurate fuel readings, why does the fuel gauge show as below? Can you tell how much fuel is left in the tank or in your own truck tank?

fuel gauge

3 Vehicle self fuel sensor normally gives out analog voltage data, which is why it can be connected with GPS tracker that supports analog input. Analog voltage data is the worst out as the output range is 0 to 5V only. RS232 or RS485 output vary from 0 to 65535. The larger the output, the more accurate the fuel monitoring. Compare below two pictures of using vehicle own sensor and external RS232 fuel sensor, you shall see the big difference and worth of using external fuel sensor.

fuel monitoring solution
fuel monitoring solution

6 What matters mostly in a complete fuel monitoring system?

A complete fuel monitoring system is composed of GPS tracker, Fuel sensor and GPS tracking software. All of them are important for a stable and accurate fuel monitoring solution.

GPS Tracker: GPS tracker must be stable and robust to be online all the time as long as there is GSM/LTE coverage.

Fuel sensor: Fuel sensor must be able to give out stable data and filter out those sudden jumps or drops of fuel while harsh braking or acceleration or turn. If not, there will be jumps and drops on fuel graph.

GPS tracking software: without a user friendly and detailed fuel monitoring software, it will be shy to offer clients such solution. Tracking software should be possible to give out detailed fuel consumption, alert of fuel theft or leak or refuel amount, as well it should aggressively listen to clients’ opinion and keep improving.

If there are more questions about fuel monitoring, we shall add it here for your reference.


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