Symptoms Diagnosis - Fuel Pumps

The quality of fuel that your engine uses or presence of water can lead to issues in the fuel pump or injection systems. It is, therefore, important that you understand what these problems can be and recognise their potential causes.

Typical signs that your fuel system needs attention can include:

• Poor starting
• Loss of power, under stress or when accelerating
• Excessive fuel consumption
• Excessive smoke
• Erratic running (surging or sputtering), cylinder knock or misfiring

Fuel contamination is the main reason behind many fuel system failures

Fuel pump symptoms

Fuel pumps are carefully engineered systems that need to be kept in good working order for your engine to perform properly. Even though Perkins fuel pump systems are highly reliable, problems can occur for a variety of reasons.

Fuel injection pumps

Most fuel pump failures are caused by internal component wear, resulting in excess fuel delivery at the wrong time. This reduces engine performance and can increase fuel consumption. Typical symptoms for fuel pump problems include;

• Pump does not switch on - failure of pump relay or lack of electrical power
• Noise from the pump. Due to wear of internal components
• Hard to start or non-starting engine
• Lack of power from the engine under load

Lift pumps

Lift pumps can fail suddenly or unexpectedly due to a range of causes. The lift pump is a low-cost item, so it is normally replaced rather than repaired. Typical lift pump issues include:

• Seized inlet or outlet valves reducing fuel flow
• Worn valve seats reducing fuel pressure
• Worn or split diaphragm reducing fuel delivery pressure
• Distorted or corroded diaphragm spring reducing fuel inlet pressure
• Worn rocker lever or lever pin resulting in complete failure to pump fuel

Perkins genuine fuel pumps are designed to ensure the fuel delivery rate and pressure are specifically matched to the engine to deliver effective power and performance. Using a non-genuine mechanical fuel pump may lead to incorrect supply pressure and affect injection timing advance mechanisms, leading to a change in engine emissions.

Contributing factors for failure

Fuel system wear is increased by lower quality fuels and water in the fuel system, with many issues caused by fuel contamination requiring component parts to be replaced. This can be due to:

• Lower quality fuels, especially those without lubrication additives
• Particle contamination in fuel, especially when inferior fuel filters have been used
• Water contamination of diesel fuel leading to corrosion and wear of injectors

The effect of dirt and water contamination can be limited by using correct fuel filters at the appropriate service intervals.