Fuel Monitoring for Trucks and Generators: How It Works

Whether you run a fleet of trucks or keep diesel generators powering a site, fuel is a major running cost. Many business owners rely on manual dipping, paper logbooks or the word of whoever filled the tank. Fuel monitoring replaces that guesswork with a live reading you can check from anywhere. This guide explains, step by step, how a typical setup works using a Eurosens Dominator fuel level sensor and a Teltonika FMB920 tracker, with the data shown on the GPSFleetmatic platform.

The two main parts

1. The fuel level sensor: Eurosens Dominator

The Eurosens Dominator is a capacitive fuel level sensor. It is a probe that is fitted vertically into the fuel tank through a small opening in the top. Inside the probe, the sensor measures how much of its length is covered by fuel. As the fuel level rises or falls, the reading changes. Because it has no moving floats, it is designed for steady, reliable measurement in vehicle and stationary tanks.

The probe is cut to match the depth of the tank and then calibrated. Calibration means recording how the sensor reading relates to the actual volume in that particular tank, because tanks come in different shapes. A properly calibrated sensor lets the platform show the fuel level in a way that matches your tank.

The Dominator comes in different output versions. For the FMB920, the version with an analog voltage output is used, because that is the type of input the tracker has.

2. The GPS tracker: Teltonika FMB920

The Teltonika FMB920 is a compact, professional GPS tracker. It reports location, ignition status and trip data, and it has an analog input. The fuel sensor's output wire connects to this analog input. The tracker reads the voltage from the sensor at regular intervals and sends it, together with the GPS position and time, over the mobile network to the tracking server.

How the data flows

The sensor measures the fuel level inside the tank continuously.
The tracker reads the sensor's analog signal and attaches location and time.
The data is sent over the mobile network to the GPSFleetmatic platform.
The platform converts the reading into a fuel level using the calibration for your tank.
You view it on your phone or computer, along with history and alerts.

If network coverage is weak for a while, the tracker stores records in its memory and sends them once the connection returns, so you keep a complete history.

What you see on the platform

Once the setup is installed and calibrated, the GPSFleetmatic platform lets you:

Check the current fuel level in each monitored tank.
Review fuel level history over time, so you can see when the tank was filled and how the level went down.
Receive alerts for changes you want to know about, such as an unusual drop in level.
See location and fuel together for vehicles, so you know where a truck was when the level changed.

We will show you exactly how this looks for your setup in a free demo.

Fuel monitoring for trucks

For trucks, fuel monitoring works alongside normal GPS tracking. You see where each truck is, the route it took and its fuel level along the way. This helps you match refuelling records to what actually went into the tank, understand consumption on each route, and have calm, fact-based conversations with drivers. Combined with route planning and idle reports, it is one of the most effective tools for fuel control. Read more in how fleet tracking cuts fuel costs.

Fuel monitoring for generators

Many businesses in Nigeria depend on diesel generators for offices, factories, telecom sites, hotels and estates. A generator tank can be fitted with the same kind of sensor, connected to a tracker installed at the generator. Instead of sending someone to dip the tank, you check the level remotely. The history shows how much was delivered and how quickly it was used, which helps with planning deliveries and understanding running hours. Alerts let you know when the level changes unexpectedly or drops low, so you can arrange a top-up in good time.

Installation: what to expect

Site check: we look at the tank type, size and access point.
Sensor fitting: the probe is cut to length and fitted securely in the top of the tank.
Wiring: the sensor is connected to power and to the tracker's analog input, neatly and safely.
Calibration: the tank is filled in measured stages to record the relationship between reading and volume.
Testing: we confirm the readings on the platform before handing over.

Good installation and careful calibration are what make the readings useful, so they are worth doing properly.

Tips for accurate readings

Make sure the sensor length suits the tank depth.
Recalibrate if the tank is changed or modified.
Remember that fuel moves while a truck is driving on rough roads, so the platform's history is more useful than a single moment's reading.
Keep the wiring protected from heat and vibration.

Is fuel monitoring right for you?

If fuel is a significant cost in your operation, or you want clearer records for trucks or generators, fuel monitoring is worth considering. It gives you visibility and peace of mind, and it makes planning much easier. For more on costs, see what decides the cost of a tracker, and visit our fuel monitoring service page.

Tell us about your trucks or generators and we will recommend the right setup. Chat with us on WhatsApp.

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