Zexel Diesel Pump Performance and Adjustment

[MikePhua]

Zexel is a brand known for its high-quality diesel fuel injection systems and pumps. The Zexel diesel pump, often used in industrial engines and heavy equipment, is a key component in controlling the engine's fuel delivery and timing. Over time, some operators may notice that their diesel pump's performance has declined or that they need to increase the fuel output to meet certain operational demands. This article explores how to identify issues with Zexel pumps, the importance of pump adjustments, and common ways to increase the diesel fuel delivery without compromising engine performance.
History of Zexel Fuel Systems
Zexel, a division of the Japanese company Diesel Kiki, was founded in the early 20th century and has since become one of the leading manufacturers of fuel injection equipment and components. Zexel's diesel pumps are designed to provide precise fuel delivery to the engine, ensuring optimal combustion and performance. These pumps are widely used in a variety of applications, including agriculture, construction, transportation, and industrial machinery. Zexel pumps are well-regarded for their durability and efficiency, making them a popular choice for both OEM and aftermarket fuel systems.
The Zexel brand is recognized for its innovative designs, such as the common rail fuel injection system and advanced diesel pump technologies. These innovations have helped reduce emissions and improve fuel efficiency, which is essential for meeting modern environmental standards and reducing operating costs.
Understanding Zexel Diesel Pumps
Zexel diesel pumps, like other high-performance fuel pumps, are responsible for supplying the correct amount of fuel to the engine's injectors at the right pressure. These pumps work by pressurizing the fuel and delivering it in precise amounts to each cylinder at the right time, ensuring that the engine operates efficiently.
The main components of a Zexel diesel pump include:

1. Plunger and Barrel: These components work together to pressurize the fuel, forcing it into the injectors. The plunger’s movement controls the amount of fuel injected into the engine.
   
2. Governor: The governor is responsible for controlling the pump’s fuel delivery based on the engine speed. It ensures that fuel is injected according to the engine's load and speed conditions.
   
3. Timing Mechanism: The timing mechanism ensures that fuel is injected into the combustion chamber at the correct point in the engine’s cycle. This is crucial for achieving optimal combustion and performance.
   
4. Fuel Control Rack: This component adjusts the amount of fuel delivered by the pump, depending on the throttle position and load on the engine.
   
5. Fuel Injection Valve: The valve controls the release of pressurized fuel to the injectors, allowing the engine to function properly under different operating conditions.
   

Why Increase Diesel Fuel Delivery?
There are several reasons why an operator might want to increase the fuel delivery of their Zexel diesel pump:

1. Increased Engine Power: One of the most common reasons for increasing fuel delivery is to boost engine power. This is especially important in heavy equipment and industrial machinery that needs more power for tasks like lifting, digging, or towing.
   
2. Engine Efficiency: Increasing the fuel delivery slightly can also improve fuel efficiency under certain conditions, such as heavy loads or long working hours, by ensuring that the engine operates at its best performance.
   
3. Compensating for Wear: Over time, as a diesel engine and its components wear, the pump may lose some of its efficiency. Increasing the fuel delivery can sometimes compensate for this wear, restoring engine power without needing a full overhaul.
   
4. Tuning for Specific Tasks: Certain tasks, such as working in high-altitude areas or extreme conditions, may require more fuel to maintain optimal performance. Adjusting the pump to deliver more fuel can help the engine perform more reliably in such environments.
   

How to Increase the Fuel Delivery on a Zexel Diesel Pump

1. Adjusting the Governor: The governor in the Zexel diesel pump controls fuel delivery based on engine speed. By adjusting the governor settings, you can increase or decrease the fuel flow to the injectors. This adjustment can be made by a technician familiar with the specific Zexel pump model. It’s important to ensure that the governor is calibrated correctly to avoid over-fueling, which can lead to engine damage.
   
2. Recalibrating the Fuel Control Rack: The fuel control rack, which adjusts the amount of fuel delivered to the engine, can be modified to provide more fuel under load. This is usually done by adjusting the mechanical or electronic controls that regulate the rack's movement. Improper adjustments can lead to poor engine performance or excessive smoke, so this process must be done carefully.
   
3. Upgrading the Fuel Injection Valve: Sometimes, increasing fuel delivery involves upgrading the fuel injection valve to a larger or higher-performance model. This will allow more fuel to be injected into the combustion chamber, improving power output and efficiency.
   
4. Replacing the Plunger and Barrel: If the plunger and barrel are worn, it may be necessary to replace them to restore proper fuel delivery. This can improve the accuracy of the fuel injection, ensuring the engine operates at optimal performance levels.
   
5. Engine Tuning: In some cases, increasing the fuel delivery might require tuning the engine to handle the additional fuel. This might involve adjusting the air-to-fuel ratio or making changes to the engine’s timing to ensure the additional fuel is properly combusted.
   

Common Problems and Solutions

1. Excessive Smoke: If the fuel delivery is increased too much, it can lead to black smoke coming from the exhaust, indicating incomplete combustion. This can be solved by reducing the fuel delivery slightly or ensuring that the engine is receiving enough air to maintain proper combustion.
   
2. Overheating: Increasing the fuel delivery can cause the engine to run hotter. Ensure that the cooling system is functioning properly, and monitor the engine temperature closely to avoid overheating.
   
3. Poor Fuel Efficiency: While increasing the fuel delivery can boost power, it can also decrease fuel efficiency if not properly calibrated. Operators should monitor fuel consumption to ensure that the benefits of increased power do not come at the cost of excessive fuel use.
   
4. Fuel Injection Failure: If the fuel pump components, such as the plunger or injection valve, become damaged from excessive fuel delivery, they may need to be replaced. Regular maintenance is essential to prevent premature wear of these components.
   

Conclusion
The Zexel diesel pump is an essential component for diesel engines in a wide range of heavy equipment and industrial applications. Increasing fuel delivery can provide more power, improve engine performance, and compensate for wear. However, it’s crucial to make adjustments carefully and ensure that the engine can handle the increased fuel flow without causing damage or excessive wear. Proper maintenance and calibration of the diesel pump are key to achieving the best results and ensuring the longevity of the engine. By understanding the components and functions of the Zexel diesel pump, operators can make informed decisions about when and how to adjust the fuel delivery for optimal performance.