When engine starting is impossible although main relay (Engine control relay) operation and CKPS, CMPS signals are normal, Inspect the rail pressure. Rail pressure must be above 120 bar (12 Mpa) while engine cranking.
If rail pressure is NOT above 120 bar (12 Mpa), engine starting is impossible because injector operation is stopped by ECM. If rail pressure is too high, Injector operation is stopped by ECM also.
IG KEY "ON", ENGINE "OFF"
Connect scantool to Data Link Connector (DLC).
Select 'Fuel Pressure', 'Rail Pressure Regulator(rail)', 'Rail Pressure Regulator(pump)' parameters on the scantool.
Remove all injector connectors (For impossible starting).
Monitor current data is selected while engine cranking.
※ Normal data
☞ Check parameters at keep cranking.
■ Normal current data
"Rail pressure measured" : approx. 25 Mpa
"Rail Pressure Regulator (rail)" : approx. 25 % duty
"Injection pump regulator (pump)" : approx. 40 % duty
☞ Check parameters at end of cranking.
■ Normal current data
"Rail pressure" is lowered suddenly.
"Rail pressure regulator (rail)" is going to be 0.0% immediately.
"Injection pump regulator (pump)" is going to be 0.0% after keeping approx. 35 % duty
Symptom | Inspection procedure | |
Case1 | ● "Rail pressure measured" is NOT above 120 bar (12 Mpa) while engine cranking. | ● Engine starting is impossible because injector operation is stopped by ECM. ● Low rail pressure is caused by almost abnormal fuel system such as leaked or blocked low pressure fuel system, leaked high pressure fuel system etc. ● If rail pressure is low, All fuel systems must be inspected. (Refer to fig.1 as below) ☞ Go to "Low rail pressure inspection" |
Case2 | ● "Rail pressure measured" is NOT above 120 bar (12 Mpa) while engine cranking. (In case of impossible engine starting after parking for a long time at below -5 ℃ in winter.) | ● Inspect blocked fuel filter because paraffin wax is frozen in diesel fuel. ● If fuel filter operation is normal after checking operation of the fuel filter heater, Inspect the diesel fuel. (whether diesel fuel is low quality, summer type fuel or not.) ● If fuel filter heater is not operated, ☞ Go to "Fuel heating system inspection" |
Case3 | ● "Rail pressure measured" is above 120 bar (12 Mpa), but hard starting occurs at cold starting. | ● In case of hard starting at cold starting, ☞ Go to "Preheating system (glow plug) inspection" |
Case4 | ● "Rail pressure measured" is above 500 bar (50 Mpa) | ● In case that "rail pressure measured" is higher than "Fuel pressure set point". It means rail pressure regulator is blocked. (Refer to fig.2 as below) ☞ Replace common rail assembly (Bank2 side). |
