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Why Bosch VP44 Fuel Pump Fail?

Posted on 3/30/2016 4:06:19 PM

In order to serve better,the diesel injection parts and common rail parts manufacturer - China Balin Parts Plant has been investigating what cause the Vp44 fuel pump failures .Before analyze that,we have to know how it works.

How Bosch 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.

Reason 1:Internal Housing Wear Failure.
As stated above,engine timing and fuel delivery is controled by VP44 which also provide pressure.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.

Reason 2: PSG, or ECU Failure. 
There is one separate computer which is connected to two internal sensors for each VP44 fuel pump.The main failure reason 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. We could solve this problem by replacing entire PSG.

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