How to Diagnose a Bad Fuel Pump?

The fuel pump is a key part of heavy equipment, moving fuel from the tank to the engine. If the fuel pump doesn't work, it can make heavy equipment difficult to start, less powerful, or even stop working. This can seriously affect how much work gets done. So, how can you diagnose and fix a faulty fuel pump? These MyMROmarts will teach you how to diagnose a bad fuel pump and help you understand the basics.

 

Common Symptoms of Fuel Pump Failure

Before starting a diagnosis, it's important to know the common symptoms of fuel pump failure:

1. Difficulty starting or failure to start equipment: When the diesel fuel pump fails to supply fuel properly, the engine will not run.

2. Insufficient power: When heavy equipment is operated under heavy load, the equipment shows insufficient power or runs unevenly.

3. Abnormal noise: The fuel pump emits a sharp buzzing or strange noise.

4. Sudden stalling: The sudden stopping of heavy equipment during operation may be caused by fuel supply interruption.

5.  Abnormal fuel consumption: A fuel pump failure may result in wasted fuel.

 

If your heavy equipment exhibits one or more of these symptoms, they all indicate that the fuel pump is perhaps faulty.

 

1. Check Fuel Pump Power Supply

Firstly, start by checking that the electrical system of the fuel pump is functioning properly.

Check the fuse and relay: The fuel pump fuse or relay can sometimes be blown due to overloading. When you find that the fuse or relay is damaged, replace it immediately.

Test the voltage: Use a multimeter to measure the voltage at the fuel pump connector. Most fuel pumps require 12 volts to operate properly.

 

2. Listen for Fuel Pump Operation

The fuel pump usually makes a slight humming sound when the ignition switch is turned on. You can determine this by the following methods:

Turn the ignition switch to the ‘ON’ position without starting the engine.

Listen for a sound near the fuel pump near the fuel tank.

If there is no sound, it may indicate that the fuel pump has failed.

 

3. Check Fuel Pressure

Insufficient fuel pressure is a clear indication of fuel pump failure.

Use a fuel pressure gauge: Connect the gauge to the fuel rail connection.

Start the engine and take a pressure reading: Check your heavy-duty equipment manual for normal fuel pressure ranges. If you find that the pressure is too low or no pressure at all, there may be a problem with the fuel pump.

 

4. Check the Fuel Filter

A clogged fuel filter can cause similar symptoms to fuel pump failure. Before replacing the fuel pump, inspect and clean the diesel fuel filter assembly.

Remove the fuel filter and check for visible clogging.

If the filter is excessively dirty, it is recommended that you replace it with a new one and retest the fuel pressure.

 

5. Check the Mechanical Components of the Fuel Pump

When the electrical circuits and fuel pressure are normal, the problem lies in the internal components of the fuel pump.

Check the gears or vanes inside the pump: Worn or seized gears and vanes can cause the fuel pump to malfunction.

Clean the inside of the pump: Some fuel pumps can accumulate a lot of contaminants due to prolonged use and need to be cleaned.

 

If none of the above steps can determine if the fuel pump is malfunctioning. You can verify the problem by replacing the fuel pump with one known to be good and compatible with the original model.

 

How Can I Avoid Fuel Pump Failure?

Having preventative maintenance can significantly extend the life of your fuel pump.

Change your fuel filter regularly, this will help prevent impurities from entering the fuel pump.

Use quality fuel, poor-quality fuel contains too many impurities and water.

Try to avoid adding new fuel when you run out of fuel, low fuel levels can cause the fuel pump to overheat.

 

Faulty fuel pumps on heavy equipment can hinder the normal operation of the equipment. With the guide in this article, you can master the basics of fuel pump diagnosis and perform effective fuel pump troubleshooting. These steps can help you quickly identify and solve fuel pump problems. If you need a replacement fuel pump or fuel filter, check out the MyMROmarts online shop for aftermarket parts.