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Generac Power Systems 65, 55, 75 manual Section ENGINE DC CONTROL SYSTEM, Circuit Condition-Running

Models: 65 75 55

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Section 5

ENGINE DC CONTROL SYSTEM

CIRCUIT CONDITION-RUNNING:

With the FUEL PUMP (FP) and FUEL SOLENOID (FS) operating and ignition occurring, the engine should start, and the START-STOP SWITCH (SW1) is released.

A voltage is induced into the Stator's BATTERY CHARGE WINDING. This voltage is delivered to the ENGINE CONTROLLER BOARD (PCB) via Wire 66 to prevent STARTER MOTOR engagement above a cer- tain rpm.

Circuit board action terminates DC output to the STARTER CONTACTOR RELAY (SCR), which then de-energizes to end cranking. Circuit board action ter- minates DC output to the CHOKE SOLENOID (CS). The choke will go to a position determined by the

CHOKE HEATER (CH).

The LOW OIL PRESSURE SWITCH (LOP) is nor- mally closed. After start-up, engine oil pressure will open the LOP.

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Generac Power Systems 65, 55, 75 manual Section ENGINE DC CONTROL SYSTEM, Circuit Condition-Running

Contents

Model 4702, 4703, 4707, 4705, 4706, Diagnostic Repair ManualQUIETPACT 55/65/75 RECREATIONAL VEHICLE GENERATORNOTICE TO USERS OF THIS MANUAL SAFETYREPLACEMENT PARTS Table of Contents SECTION Table of ContentsELECTROMAGNETIC INDUCTION Section GENERATOR FUNDAMENTALSMAGNETISM ELECTROMAGNETIC FIELDSFigure 1-6.– A More Sophisticated Generator A SIMPLE AC GENERATORA MORE SOPHISTICATED AC GENERATOR Figure 1-5.– Alternating Current Sine WaveSection GENERATOR FUNDAMENTALS Figure 1-7.- Generator Operating DiagramSection GENERATOR FUNDAMENTALS FIELD BOOSTGENERATOR AC CONNECTION SYSTEM Section GENERATOR FUNDAMENTALS Figure 1-8.– Connection for 120 Volts OnlyFigure 2-1.Exploded View of Generator ROTOR ASSEMBLYSTATOR ASSEMBLY Section MAJOR GENERATOR COMPONENTSBRUSH HOLDER BATTERY CHARGE COMPONENTSFigure 2-4.– Battery Charge Circuit Figure 2-5.– Schematic: Excitation CircuitSection MAJOR GENERATOR COMPONENTS CRANKCASE BREATHERFigure 2-6.– Excitation Circuit Breaker Section MAJOR GENERATOR COMPONENTS CONTROL PANEL COMPONENT IDENTIFICATIONFigure 2-9.– Control Panel Components INSULATION RESISTANCE TESTERS CLEANING THE GENERATORSection INSULATION RESISTANCE TESTS EFFECTS OF DIRT AND MOISTURESection INSULATION RESISTANCE TESTS STATOR INSULATION RESISTANCEFigure 3-3.– Rotor Test Points TESTING ROTOR INSULATIONTHE MEGOHMMETER Figure 3-2.– Stator LeadsMEASURING AC VOLTAGE Section MEASURING ELECTRICITYMETERS THE VOMFigure 4-3.– A Line-Splitter MEASURING AC FREQUENCYMEASURING CURRENT MEASURING RESISTANCEAMPERES = VOLTSOHMS ELECTRICAL UNITSOHMS LAW FigureOPERATIONAL ANALYSIS Section ENGINE DC CONTROL SYSTEMINTRODUCTION Page Section ENGINE DC CONTROL SYSTEMCIRCUIT CONDITION- PRIMING CIRCUIT CONDITION- CRANKING Section ENGINE DC CONTROL SYSTEMCIRCUIT CONDITION-RUNNING Section ENGINE DC CONTROL SYSTEMCIRCUIT CONDITION- SHUTDOWN Section ENGINE DC CONTROL SYSTEMSection ENGINE DC CONTROL SYSTEM CIRCUIT CONDITION- FAULT SHUTDOWNFigure 5-2.- Receptacle J1 BATTERYENGINE CONTROLLER CIRCUIT BOARD Figure 5-3.– Engine Controller Circuit Board7.5 AMP FUSE FUEL PRIMER SWITCHSTART-STOPSWITCH Figure 5-5.– Primer Switch& STARTER MOTOR Figure 5-6.– Start-StopSwitchSection ENGINE DC CONTROL SYSTEM STARTER CONTACTOR RELAYINTRODUCTION Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSPage Section TROUBLESHOOTING FLOWCHARTSTEST 2- CHECK ENGINE GOVERNOR Section DIAGNOSTIC TESTSFigure 7-1.– Governor Adjustment Points TEST 1- CHECK NO-LOADVOLTAGE AND FREQUENCYFigure 7-3.- Fixed Excitation Test TEST 3- TEST EXCITATION CIRCUIT BREAKERTEST 4- FIXED EXCITATION TEST/ROTOR AMP DRAW Figure 7-2.– Excitation “DPE” Circuit BreakerSection DIAGNOSTIC TESTS TEST 5- WIRE CONTINUITYFigure 7-5.– Stator Excitation Winding TEST 6- CHECK FIELD BOOSTTEST 7 - TEST STATOR DPE WINDING Figure 7-4.- The Field Boost CircuitSection DIAGNOSTIC TESTS TEST 8- CHECK SENSING LEADS / POWER WINDINGSFigure 7-7.– Brush Leads Figure 7-6.– Stator Power Winding LeadsTEST 9- CHECK BRUSH LEADS TEST 10 - CHECK BRUSHES & SLIP RINGSFigure 7-9.– Main Breaker Typical TEST 11- CHECK ROTOR ASSEMBLYFigure 7-8.– Rotor Assembly TEST 12 - CHECK MAIN CIRCUIT BREAKERTEST 14- CHECK LOAD WATTS & AMPERAGE TEST 15 - CHECK BATTERY CHARGE OUTPUTTEST 16 - CHECK BATTERY CHARGE RECTIFIER TEST 13- CHECK LOAD VOLTAGE & FREQUENCYSection DIAGNOSTIC TESTS TEST 17 - CHECK BATTERY CHARGEWINDINGS / BATTERY CHARGE RESISTOR Figure 7-10.- Battery Charge RectifierTEST 18 - TRY CRANKING THE ENGINE TEST 19- TEST PRIMER SWITCHFigure 7-11.– Primer Switch Figure 7-12.– Harness End of ConnectorSection DIAGNOSTIC TESTS TEST 20- CHECK FUEL PUMPFigure 7-13.- The LPG Fuel Solenoid FS Figure 7-14.– Electric Fuel PumpFigure 7-15.– Harness to Fuel Pump TEST 22- CHECK BATTERY & CABLESTEST 23- CHECK POWER SUPPLY TO CIRCUIT BOARD TEST 21- CHECK 7.5 AMP FUSESection DIAGNOSTIC TESTS TEST 24 - CHECK START-STOPSWITCHFigure 7-17.- Start-StopSwitch Figure 7-18.– Test 24, StepSection DIAGNOSTIC TESTS TEST 25 - CHECK POWER SUPPLY TO WIRETEST 26- CHECK STARTER CONTACTOR RELAY Figure 7-19.– Starter Contactor RelaySTEP 1 TEST POINT TEST 26A - CHECK STARTER CONTACTORTEST 27 - CHECK STARTER MOTOR Figure 7-20.– The Starter Contactor SCSection DIAGNOSTIC TESTS Figure 7-21.- Starter Motor SMFigure 7-22.- Check Pinion Gear Operation Section DIAGNOSTIC TESTS Figure 7-26.– Testing Starter Motor PerformanceTEST 28- CHECK FUEL SUPPLY Figure 7-24.– TachometerSection DIAGNOSTIC TESTS Figure 7-28– LP Gas Carburetion DiagramFigure 7-27- Typical Propane Gas Fuel System Figure 7-29.– Fuel Regulator TEST 29 - CHECK WIRE 14 POWER SUPPLYTEST 30 - CHECK WIRE Figure 7-30.– The 4-tabConnectorSection DIAGNOSTIC TESTS Figure 7-31.– Remote Harness ConnectorTEST 31 - CHECK FUEL SOLENOID GASOLINE MODELS TEST 32 - CHECK IGNITION SPARKSection DIAGNOSTIC TESTS Figure 7-32.– Testing Ignition SystemFigure 7-33.– Checking Engine Miss Figure 7-34.– Cylinder Balance TestTEST 33 - CHECK SPARK PLUGS TEST 34 - CHECK AND ADJUST IGNITION MAGNETOSFigure 7-35– Setting Spark Plug Gap Figure 7-36.– Ignition Magneto AssemblyFigure 7-39.– Diode Failure Diagnosis Figure 7-37.– Setting Ignition MagnetoArmature Air Gap Figure 7-38.– Engine Ground HarnessSection DIAGNOSTIC TESTS TEST 35 - CHECK VALVE ADJUSTMENTFigure 7-41– Adjusting Valve Clearance Figure 7-40.- Engine Ground Harness Test PointsSection DIAGNOSTIC TESTS TEST 36 - CHECK CARBURETIONTEST 37 - CHECK CHOKE SOLENOID Figure 7-42- Tightening the Jam NutSection DIAGNOSTIC TESTS Figure 7-43.- ConnectorFigure 7-44.– Exploded View of Choke Assembly Figure 7-45.– Automatic Choke AssemblySection DIAGNOSTIC TESTS DOWN TEST / COMPRESSION TESTTEST 38 - CHECK ENGINE / CYLINDER LEAK Figure 7-47.– Oil Temperature Switch TEST 39 - CHECK OIL PRESSURE SWITCHTEST 40 - TEST OIL TEMPERATURE SWITCH Figure 7-46.– Oil Pressure SwitchSection DIAGNOSTIC TESTS Figure 7-48.– Testing Oil Temperature SwitchTEST 41 - TEST CHOKE HEATER TEST 42 - CHECK LPG FUEL SOLENOIDSection DIAGNOSTIC TESTS Figure 7-49.– Fuel SolenoidMAJOR DISASSEMBLY Section ASSEMBLYSection ASSEMBLY Figure 8-1.– Drive Belt Tension10.Remove blower housing Section ASSEMBLYPage NOTESBase & Pulley – Drawing No. 0E1323-A Section Exploded Views / Part NumbersDESCRIPTION Section Exploded Views / Part NumbersITEM PART NO. QTYEnclosure – Drawing No. 0E1011-B Section Exploded Views / Part NumbersPART NO SectionExploded Views / Part Numbers ITEMSheet Metal – Drawing No. 0E1012-E Section Exploded Views / Part NumbersITEM Section Exploded Views / Part NumbersControl Panel - Drawing No. 0E1013-A Section Exploded Views / Part Numbers0C2375 Section Exploded Views / Part Numbers760 V-TwinEngine – Drawing No. 0E1014-B Section Exploded Views / Part Numbers0C5730A Section Exploded Views / Part NumbersLP Regulator - Drawing No. 0E1530 Section Exploded Views / Part Numbers0D5694 SectionExploded Views / Part Numbers Section SPECIFICATIONS & CHARTS Section SPECIFICATIONS & CHARTSGENERATOR SPECIFICATIONS NOMINAL RESISTANCES OF GENERATOR WINDINGS AT 68FRV TORQUE REQUIREMENTS ENGINE SPEEDS AND VOLTAGE SPECIFICATIONSLONG BLOCK TORQUE REQUIREMENTS TRIM TORQUE REQUIREMENTSPage NOTESSection ELECTRICAL DATA Page Section ELECTRICAL DATAPRINTED IN THE USA/9.03 PO BOX 297 WHITEWATER, WIP/N OE7225 REV O