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 GDS(scantool) to Data Link Connector (DLC).
Select 'Fuel Pressure' and 'Rail Pressure Regulator(pump)' parameters on the GDS(scantool).
Remove all injector connectors (For impossible starting).
Monitor current data is selected while engine cranking.
※ Normal data
■ Above data is normal starting data after cranking, Inspect as below.
☞ Monitor that 'Rail pressure' is increased quickly at cranking. (Over 12 MPa)
☞ Monitor that 'Rail pressure' is kept 27 MPa after starting.
☞ Monitor that 'Rail pressure' is kept 25 Mpa after IG key 'OFF'. ( After IG key off, 'Rail pressure' is kept before main relay 'OFF'. )
Symptom | Inspection procedure | |
Case1 | ● Fuel Pressure' 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. ☞ Go to 'Low rail pressure inspection' |
Case2 | ● Fuel Pressure' 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 | ● Fuel Pressure' 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 | ● Fuel Pressure' is above 500 bar (50 Mpa) while engine cranking. | ● In case of rail pressure regulator (pump) open stuck. ☞ Go to 'High rail pressure inspection' procedure. |
Case5 | ● In case that Rail pressure is released quickly after IG key 'OFF'. (After IG key 'OFF', Rail pressure must be kept before main relay 'OFF' in the normal condition.) | ● In case of rail pressure regulator (pump) open stuck or fuel leakage in the injector. ☞ Go to 'Low rail pressure inspection' |
