Engine-Fuelinjectionsystem
Fuelinjectionsystem-Dynamicdescription-Electrical
ThePumpControlValveL-52isoneoftheoutputdevicesassociatedwiththefuelsystem.Thesolenoidcontrolsthe
supplyoilthatowstothehighpressurepump,byreceivingaPulseWidthModulationPWMsignalfromtheEngine
ControlUnitA-01.
SimpliedCircuitDiagram
NHPE11CR00089AA1
Figure1
NOTE:Figure1isasimpliedfunctionaldiagramoftheFuelHighPressurecircuit.
Atkey-on,A-01willreceivekeyswitchedpowerfromKeySwitchS-02anditsignitioncircuitiscomplete.
Priortofuelsystemoperation,the(normallyopencontact)SeatSwitchS-02mustbeclosedandthe(normallyopen
contact)ParkBrakeSwitchS-28mustbeintheONposition.
AfterstartingthecombinewiththeS-28intheONposition,theA-01monitorstofueltemperature,pressure,andthe
amountofwaterinthefuel.TheWaterinFuelSensorB-59detectsifwaterispresentinthefuelandreportstothe
A-01.TheFuelLevelSensorR-01monitorsthefuellevelinthefueltank.Asthefuellevelrisesorlowersthevariable
resistanceofthesensorchangesandthosechangesarerecordedtheCombineControlModule2CCM-2andthe
CCM-2displaystheappropriatelevelontheoperatorgaugeandsendstheleveldatatoA-01,usingthesharedCAN
lines.
Themaincomponentofthefuelsystemisthevolatilitylevelandthefuelpressureandtemperaturedictatesthatlevel.
TheFuelTemperatureSensorB-36andtheFuelPressureSensorB-67monitorsthetemperatureandpressure,then
reportsanychangestoA-01.Thefueltemperaturehastobemaintainsothefuelcanbeeasilyvaporizes.Andthe
fuelpressurehastobehighenoughtoatomizesthefuel.Inthecasewhenthefuelpressureistoolow,theA-01sends
an12VoutputsignaltotheL-52.TheenergizedL-52opensapathforthesupplyoiltoowtothehighpressure
pump,toincreasethefuelpressureforproperatomization.
Thefuelsystemthenroutesthehighpressurefueltothefuelrail,whereitisstoreduntiltheA-01energizesoneof
theengine'sfuelinjectors.
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