Common Bosch VP44 Fuel Pump Failures and Fixes


In a previous post, we covered common rail injectors, why they fail, and what is being done to correct some of the failures we are all seeing when these injectors come from the factory. Through our internal Research and Development department at BDG, we have also been investigating the major causes of the Vp44 fuel pump failures, and what could be done to make the pump last longer, operate more efficiently, and gain some reliability. The result of this research, how the VP44 works, why it fails, and how we are improving the design, is described below.

How Does the VP44 Fuel Pump Work?

The VP44 fuel pump is an electronic rotary pump that delivers fuel at extremely high pressures, and additionally controls the fuel flow rate and timing for the engine. The added responsibility of controlling the flow rate and timing means additional electronics, and also means that the VP44 has, in addition to physical part failure due to the constant high pressure and wear inside the housing, the opportunity for electrical failure through the on-board PSG, or ECU. These two failures account for the vast majority of VP44 fuel pump failures.

Internal Housing Wear Failure.

As stated earlier, the VP44 not only provides pressure, it controls engine timing and fuel delivery. As the timing is constantly changing, the internal component that moves to create this timing movement, the timer piston, is under constant motion, and under constant pressure. With time, the friction of this movement creates wear and grooves in the pump housing. Since the timer piston works under a pressure principle, it needs to maintain pressure on one side to cause movement. Once wear and grooves are created in the pump housing, fuel leaks from either side, balancing pressure, and the piston ceases movement. Once this starts to happen, the pump loses timing advance, the engine loses power, and you consume more and more fuel. The repair for this condition is replacement of the pump housing and internal parts.

PSG, or ECU Failure. 

Each VP44 fuel pump has a separate computer connected to two internal sensors. The main cause of failure we see here is with the wires connecting the two internal sensors to the PSG. The pump itself creates considerable heat, and after enough heat cycles, the wires and connectors become brittle, split, crack and fail. Additionally, we have seen failures of the PSG and sensors themselves, though this is less common. The solution here is to replace the entire PSG.

What Does Baileys Do?

With the addition of the re-manufactured VP44 fuel pump to the Common Rail parts we offer, we replace ALL common causes of failure, regardless of cost.

Every BDG VP44 fuel pump comes with complete and 100% replacement of:

  • Complete Pump Housing
  • All O-rings, Seals and Gaskets
  • All Rollers, Bearings and Bushings.

This is why, as with our Baileys Blueprinted Injectors, we can offer the incredible BDG warranty, 2 years/100,000 kms on our new VP44 fuel pumps – because at Baileys, our brief is quality, at an affordable price.