1 The VP44 pump? How does it work and what faults can occur?

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Diesel Fuel Injection Specialists

What's the low down on the VP44 pump?



The low-down on VP44 pumps.

What is the VP44 and how does it work?

The VP44 fuel pump is an electronically controlled rotary fuel injection pump; the pump controls the injection quantity & timing of the fuel injection.

Engines that use these pumps also use mechanical injectors which control injection pressure (400bar approx. nominal pressure).

The pump control unit (PCU) controls the timer control valve (TCV) rotor solenoid and receives signal from the pump speed sensor.

The pump generates a great amount of heat while creating these injection pressures and the TCV also gets extremely hot.

What faults can occur?

These pumps suffer from electrical failures such as insulation on wires to the TCV becoming brittle from heat and shorting out, as well as a complete failure of the PCU which can stop the vehicle from starting and sometimes even prevent detecting failure with a scan tool. If an electrical failure occurs, it is necessary to remove the pump.

Common mechanical failures are worn pump housing and timer piston, reduced power and fuel economy, increased exhaust smoke, head and rotor can cause hard starting or not starting at all.

Each vehicle manufacturer has specific fault codes but some of the more common Nissan codes we see are: 0703, 0704, 0705, 0707 (73,74,75,77).

What should you do?

Call the team at Hi Tech Diesel for advice on diagnosing these types of pump problems. The more info (fault codes etc.) provided to us, the better our team can help. We also have some removal and installation notes which may assist.

We can also supply parts necessary to fit an exchange pump (or we can rebuild your pump if you prefer).

Give the team a call today!

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