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Diagnose the fail of direct injection high-pressure fuel pump

Posted on 1/22/2016 10:31:08 AM

With the strictly emission rule comes out,diesel engine manufacturers are focus on developing new generation of Common rail systems.For direct fuel injection,the high-pressure fuel pump is its important key.Someone are scared by the diagnostic of direct fuel injection.In fact,if you know what to pay attention to,you will know what cause the High-pressure fuel pumps to malfunction and/or fail.Today China Balin Parts Plant,reliable manufacturers for common rail parts,will introduce seven factors for that:

1.Lack of Maintenance
The first and main factors which might cause high-pressure fuel pumps fail is a lack of oil changes.
Wear between the camshaft lobes and the high-pressure pump follower prevents the pump from generating enough piston movement. Less movement of the pump means less pressure.

In order to avoid installing costly new high-pressure fuel pump,you need to examine the lobes on the camshaft ahead of time.A lack-of-power complaint may improve, but it will never be completely corrected.

2. Wrong Oil
Because different OEMs have its own required oil standards.So you need to check whether the oil you use could meet this OE specifications correspondently.This will prevent premature wear on the camshaft and high-pressure fuel pump follower. 
3.Pressure and Temperature Sensors
Although a failed sensor can't cause a pump to fail,it will bring you to misdiagnose a high-pressure fuel pump. In order to determine position of the high-pressure pump solenoid,pressure and in some cases temperature sensors is used by Direct-injection systems.These sensors generate the information to make the best possible combustion event.Meanwhile comparing to the older port fuel-injected -systems,it will alsothrow you a diagnostic curve ball.

These sensors have a ±2% accuracy rate.The fuel trims will be affacted if the sensors are malfunctioning.If a sensor fails or is generating readings outside of set parameters, the system will go into a low-pressure safe mode to prevent damage to the system.The best way to diagnose sensors is with a scan tool to help interpret the data.

4. Leaks
A direct injector is under a lot of pressure, so leaks can happen.There is possiblity for the leak to happen when the engine is resting.It will bring the result in  severe carbon buildup and a rich fuel reading.Meanwhile the leak will also also cause a longer than normal cranking cycle and possible wear.In order to keep a specific amount of pressure in the system when the engine is turned off,most systems are equipped with a specified resting pressure.Values can be monitored using a scan tool.

The test of injector balance test and leakdown are typically included in a enhanced or factory scan tool. These tests can help to spot a leaking injector or pump.

5. Old Calibrations, Reflash Required
As engineers squeeze every bit of energy out of a droplet of fuel, every element in the system is operating on a razor’s edge of driveability problems. Sometimes they get it wrong and they don’t find out until a direct-injection system is in the field and racking up warranty claims.Injector pulses,together with pump pressures, camshaft position and pressure solenoid position,can be calibrated to give the best performance and component life.If you are diagnosing a driveability problem on a direct-injection vehicle or replacing a high-pressure pump, make sure the ECU has the latest calibration.Wear problems and driveablity issues could be solved by the newer calibrations.Meanwhile it might also help you to prevent from replacing the pump.

6. Fuel Pump Pressure Solenoid
Through changing the stroke and/or port location,high-pressure fuel pumps use a solenoid to control the volume and pressure of the pump.When this solenoid fails, it will be in a low-pressure setting.

7. Ignoring the Signs
Some people like to drive with their check engine light on. They assume it will go out if they put better fuel in the tank, but we all know that this is not true.A direct-injection engine that has a high-pressure pump issue will go into a limp or low-pressure mode. In this mode, the in-tank pump will take over and the open time of injector will increase.

The injector is precisely pulsing the injector multiple times to create the best possible fuel/air mixture when the direct injection is working. In a low-pressure mode, it is less precise.The car will start and run.While it will reduce the performance and harm the catalyst.Finally the engine wear will also happen.

For more common rail systems problem,you could ask China Balin Parts Plant for professional assistance.

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