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​Symptoms of a Failing Diesel Fuel Pump

Apr 14th 2022

automotive fuel injection pump for a diesel engine

Diesel engines need a steady stream of fuel to generate power. That’s where your diesel fuel pump comes into play. This powerful component sends fuel into the combustion chamber where it mixes with highly pressured air before combusting. The fuel system needs to maintain a precise ratio of air and fuel to maximize efficiency. The pump is just one part of a much larger process. If any of these parts break down, your engine may burn through more fuel than necessary, assuming it fires at all.

Learn what happens when your diesel fuel pump goes bad and what you can do to prevent your pump from failing.

What Is a Diesel Fuel Pump?

The fuel pump is responsible for throttling the amount of fuel that goes into the combustion chamber. The pump pressurizes the fuel as it enters the chamber. Diesel fuel injectors spray the pressurized fuel into the chamber as a fine mist as it mixes with the pressurized air to generate power.

Inline injection pumps, or jerk pumps, use plungers to force the pressurized fuel into the chamber. The plungers are controlled by a mechanical cam that’s connected to the engine. The cam increases the flow of fuel based on how much is needed to power the engine.

More sophisticated electronic rotary pumps use electronic signals to adjust the amount of fuel that enters the chamber. The injection control pressure sensor records the pressure of the fuel in the injectors. The injection pressure regulator (IPR) valve will then adjust the pressure based on the signal it receives from the vehicle’s electrical computer.

working on a diesel injection pump

Your fuel also passes through a series of particulate filters before reaching the combustion chamber. These filters remove debris and particulate matter that can clog your pump’s fuel line and injectors.

Diesel Fuel Pump Symptoms and Problems

Your diesel fuel pump depends on a number of sensors and mechanical parts. If any one of these components breaks down, the engine won’t be able to do its job.

Watch out for these warning signs that something is wrong with your diesel fuel pump:

Loss of Power

The pump should be able to deliver enough fuel to power the engine based on the situation at hand. If there isn’t enough fuel in the chamber, you will experience a sudden loss of power.

Poor Acceleration

Forcing your engine to work harder only puts more pressure on your fuel pump. Heavy towing, driving uphill and fast accelerations can overwhelm the pump if it is damaged or clogged in any way. The pace of acceleration is directly tied to the amount of fuel passing through the fuel pump. If your fuel system is having trouble delivering fuel to the combustion chamber, your vehicle won’t be able to accelerate as quickly.

Squeaking Sounds

When you step on the gas or tow a large load, you may hear squeaking sounds coming from your diesel fuel system. This is a sign that your pump is having trouble delivering fuel into the combustion chamber.

No Fire

The pump needs to send fuel to the chamber to start the engine. If the pump can’t deliver fuel to the chamber, you won’t be able to start your vehicle at all.

Dirty Fuel

Putting poor quality fuel into your fuel system is never a good idea. Dirty fuel contains more particulate matter than regular diesel fuel. These particles will clog the various components in the fuel system, including the fuel pump, fuel injectors, and diesel fuel filters. Excess residue will clog fuel passageways, making it harder for the fuel pump to deliver fuel to the combustion chamber. This can starve the engine and lead to a loss of power and poor fuel efficiency. You should always use clean, high-quality diesel-grade fuel. Store your fuel in a sealed container at room temperature to prevent contamination. The longer you store your fuel, the more likely it is to spoil. Use fuel additives to break up particulate matter to preserve the shelf life of your fuel.

Too Little Fuel

If the combustion chamber doesn’t receive enough fuel necessary to generate power, it can damage various components throughout the fuel system. When there isn’t enough fuel in the tank, your fuel pump might send air through the fuel system instead of gas, which starves the engine. The vehicle will need to shut down until all the air has been removed.

Driving around without enough fuel in the tank can also force dirtier fuel through the engine. That’s because the poorest quality fuel settles at the bottom of the fuel tank. Sediment and other particulate matter will then pass through the fuel pump, fuel filter, and fuel injector, increasing the risk of clogs. Not having enough fuel can be particularly dangerous for the fuel injectors because they use the fuel as a lubricant. When the fuel is low, the injectors will grind to a halt.

Injection Pressure Regulator (IPR) Valves Need Replacing

If you have an electronic diesel fuel pump, there may be a problem with the IPR valve or ICP sensor. These devices set the pace of the fuel delivery system. You can test the pressure of the fuel to see if these sensors are working properly. You can find diesel fuel system replacement parts online to resolve the issue.

mechanic testing a diesel injector

Clogged Filters

If your pump is clogged or using dirty fuel, your filters will likely be the first to go. The excess particulate matter will clog both of the fuel filters, which reduces the amount of fuel in the combustion chamber. Inspect your fuel filters regularly to see if they are accumulating particles faster than usual. Once your filters clog, the pump will have to work harder to move fuel into the chamber, which can further damage your fuel system.

Problems with the Fuel Injectors

The same may also be true of your diesel fuel injectors. These parts can clog or leak over time. They are an essential component of your diesel fuel system. Watch out for symptoms of failing injectors and clean them regularly to help your fuel pump do its job.

Improper Calibration

If you notice some of these problems behind the wheel, your fuel pump may not be properly calibrated. It could be out of sync with the engine control module or injection pressure regulator. You can perform a diagnostic test to see if the pump needs recalibrating before you shell out money for an expensive rebuild. You’ll need a special testing kit and equipment to complete the test or visit your local mechanic.

Check Engine Light Comes on

Last, but not least, the check engine light should alert you to any one of the problems mentioned above. It will likely indicate a lack of fuel in the combustion chamber, which could be due to a clog.

Find a Replacement IPR Valve 7.3

Your diesel fuel pump should last approximately 100,000 miles. It will start to wear down with time, but there are several things you can do to extend the life of your pump.

Use diesel fueladditives to break up particles that can clog your filters. Clean your injectors regularly and keep an eye on your filters to see if you are using dirty fuel.

If you fall behind on regular maintenance, you risk damaging your pump beyond repair. Consider replacing your diesel fuel pumps before the problem gets worse to avoid damaging the other components of your engine.

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