8829911

1.

Connect scan tool with 'DATA LINK CONNECTOR'(DLC).

2.

Warm engine up to normal operating temperature.

3.

Turn all the electrical devices including air conditioner OFF.

4.

Monitor "FUEL PRESSURE MEASURED", "FUEL PRESS. SET POINT", "RAIL PRESS. REGULATOR" and "INJ. PUMP REGULATOR" parameter on the scan tool.

Reference value : "FUEL PRESSURE MEASURED" is similar to "FUEL PRESSURE SET POINT".

"FUEL PRESSURE MEASURED" and "FUEL PRESSURE SET POINT" : approx. 29 Mpa

"RAIL PRESS. REGULATOR" : approx. 19%

"INJ. PUMP REGULATOR" : approx. 30%

Fig.1) Monitor "FUEL PRESSURE MEASURED" at idle after warming engine up.

☞ Check if "FUEL PRESSURE MEASURED" data is similar to "FUEL PRESS. SET POINT".

Not only former two data but also "RAIL PRESSURE REGULATOR" and "INJ. PUMP REGULATOR" should be monitored carefully.

Although "FUEL PRESSURE MEASURED" is similar to "FUEL PRESS. SET POINT", if "RAIL PRESSURE REGULATOR" and "INJ. PUMP REGULATOR" is out of specification, it means wear, leakage, stuck of fuel system.

5.

Connect scan tool with 'DATA LINK CONNECTOR'(DLC).

6.

Warm engine up to normal operating temperature.

7.

Turn all the electrical devices including air conditioner OFF.

8.

Monitor "FUEL PRESSURE MEASURED", "RAIL PRESSURE REGULATOR" and "INJ. PUMP REGULATOR" parameter on the scan tool.

	Idle (No load)	3000RPM (No load)
FUEL PRESSURE MEASURED	approx. 29 Mpa	Refer to the below graph.	Pressure increases
RAIL PRESSURE REGULATOR(Rail)	approx. 19 %		Duty increases
RAIL PRESSURE REGULATOR(Rail)	approx. 19 %		Duty decreases

☞ P-PRV installed on high pressure pump is controlled to reduce duty in order to increase rail pressure at acceleration. (P-PRV operating current decreases) → IF the current decreases, fuel amount to common rail from high pressure increases.

☞ Duty for PRV installed on common rail is increased in order to make rail pressure up at acceleration(PRV Operating current increases) → If the current increases, fuel feeded to common rail return amount is decreased that makes common rail pressure increases.

caution

The waveform of fuel pressure regulator valve installed at high pressure pump(fuel detecting MPROP) shows approx. 30% duty at idle, duty decreases to approx. 25% at acceleration to raise rail pressure.The waveform of rail pressure regulator valve installed at common rail shows approx. 19% duty at idle, duty rises to approx. 45% at acceleration to raise rail pressure.