Manuals / Generac Power Systems / Lawn and Garden / Portable Generator

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

Models: 65 75 55

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CIRCUIT CONDITION- CRANKING:

Section 5

ENGINE DC CONTROL SYSTEM

CIRCUIT CONDITION- CRANKING:

When the START-STOP-SWITCH (SW1)or REMOTE PANEL START SWITCH is held at “START” position, Wire 17 from the Engine controller circuit board is con- nected to frame Ground. Circuit board action will then deliver battery voltage to a STARTER CONTACTOR RELAY (SCR) via wire 56, and to a automatic CHOKE SOLENOID (CS) via Wire 90.

When battery voltage energizes the STARTER CON- TACTOR RELAY (SCR), Its contacts close and battery output is delivered to the STARTER CONTACTOR (SC) via Wire 16. The STARTER CONTACTOR (SC) ener- gizes and its contacts close, battery output is delivered to the STARTER MOTOR (SM) via Wire 16.The STARTER MOTOR energizes and the engine cranks.

When the STARTER CONTACTOR RELAY (SCR) closes, Battery voltage is also delivered to the circuit board pin location J1-13 via Wire 16. This voltage is reduced and used for field boost and is outputted from pin location J1-9.

While cranking, the CHOKE SOLENOID (CS) is ener- gized cyclically by circuit board action (two seconds on, two seconds off).

Also while cranking, circuit board action energizes CIRCUIT BOARD TERMINAL J2 and delivers battery voltage to the Wire 14/14A circuit. This energizes the FUEL PUMP (FP) ,FUEL SOLENOID (FS) and CHOKE HEATER (CH) and optional light or hourmeter in remote panel.

Circuit board action holds open Wire 18A to common ground. The Magneto will induce a spark during cranking.

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

Contents

RECREATIONAL VEHICLE GENERATOR Diagnostic Repair ManualQUIETPACT 55/65/75 Model 4702, 4703, 4707, 4705, 4706,REPLACEMENT PARTS SAFETYNOTICE TO USERS OF THIS MANUAL Table of Contents Table of Contents SECTIONELECTROMAGNETIC FIELDS Section GENERATOR FUNDAMENTALSMAGNETISM ELECTROMAGNETIC INDUCTIONFigure 1-5.– Alternating Current Sine Wave A SIMPLE AC GENERATORA MORE SOPHISTICATED AC GENERATOR Figure 1-6.– A More Sophisticated GeneratorFigure 1-7.- Generator Operating Diagram Section GENERATOR FUNDAMENTALSGENERATOR AC CONNECTION SYSTEM FIELD BOOSTSection GENERATOR FUNDAMENTALS Figure 1-8.– Connection for 120 Volts Only Section GENERATOR FUNDAMENTALSSection MAJOR GENERATOR COMPONENTS ROTOR ASSEMBLYSTATOR ASSEMBLY Figure 2-1.Exploded View of GeneratorFigure 2-5.– Schematic: Excitation Circuit BATTERY CHARGE COMPONENTSFigure 2-4.– Battery Charge Circuit BRUSH HOLDERFigure 2-6.– Excitation Circuit Breaker CRANKCASE BREATHERSection MAJOR GENERATOR COMPONENTS Figure 2-9.– Control Panel Components CONTROL PANEL COMPONENT IDENTIFICATIONSection MAJOR GENERATOR COMPONENTS EFFECTS OF DIRT AND MOISTURE CLEANING THE GENERATORSection INSULATION RESISTANCE TESTS INSULATION RESISTANCE TESTERSSTATOR INSULATION RESISTANCE Section INSULATION RESISTANCE TESTSFigure 3-2.– Stator Leads TESTING ROTOR INSULATIONTHE MEGOHMMETER Figure 3-3.– Rotor Test PointsTHE VOM Section MEASURING ELECTRICITYMETERS MEASURING AC VOLTAGEMEASURING RESISTANCE MEASURING AC FREQUENCYMEASURING CURRENT Figure 4-3.– A Line-SplitterFigure ELECTRICAL UNITSOHMS LAW AMPERES = VOLTSOHMSINTRODUCTION Section ENGINE DC CONTROL SYSTEMOPERATIONAL ANALYSIS CIRCUIT CONDITION- PRIMING Section ENGINE DC CONTROL SYSTEMPage Section ENGINE DC CONTROL SYSTEM CIRCUIT CONDITION- CRANKINGSection ENGINE DC CONTROL SYSTEM CIRCUIT CONDITION-RUNNINGSection ENGINE DC CONTROL SYSTEM CIRCUIT CONDITION- SHUTDOWNCIRCUIT CONDITION- FAULT SHUTDOWN Section ENGINE DC CONTROL SYSTEMFigure 5-3.– Engine Controller Circuit Board BATTERYENGINE CONTROLLER CIRCUIT BOARD Figure 5-2.- Receptacle J1Figure 5-5.– Primer Switch FUEL PRIMER SWITCHSTART-STOPSWITCH 7.5 AMP FUSESTARTER CONTACTOR RELAY Figure 5-6.– Start-StopSwitchSection ENGINE DC CONTROL SYSTEM & STARTER MOTORSection TROUBLESHOOTING FLOWCHARTS INTRODUCTIONSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageSection TROUBLESHOOTING FLOWCHARTS PageTEST 1- CHECK NO-LOADVOLTAGE AND FREQUENCY Section DIAGNOSTIC TESTSFigure 7-1.– Governor Adjustment Points TEST 2- CHECK ENGINE GOVERNORFigure 7-2.– Excitation “DPE” Circuit Breaker TEST 3- TEST EXCITATION CIRCUIT BREAKERTEST 4- FIXED EXCITATION TEST/ROTOR AMP DRAW Figure 7-3.- Fixed Excitation TestTEST 5- WIRE CONTINUITY Section DIAGNOSTIC TESTSFigure 7-4.- The Field Boost Circuit TEST 6- CHECK FIELD BOOSTTEST 7 - TEST STATOR DPE WINDING Figure 7-5.– Stator Excitation WindingTEST 8- CHECK SENSING LEADS / POWER WINDINGS Section DIAGNOSTIC TESTSTEST 10 - CHECK BRUSHES & SLIP RINGS Figure 7-6.- Stator Power Winding LeadsTEST 9- CHECK BRUSH LEADS Figure 7-7.- Brush LeadsTEST 12 - CHECK MAIN CIRCUIT BREAKER TEST 11- CHECK ROTOR ASSEMBLYFigure 7-8.– Rotor Assembly Figure 7-9.- Main Breaker TypicalTEST 13- CHECK LOAD VOLTAGE & FREQUENCY TEST 15 - CHECK BATTERY CHARGE OUTPUTTEST 16 - CHECK BATTERY CHARGE RECTIFIER TEST 14- CHECK LOAD WATTS & AMPERAGEFigure 7-10.- Battery Charge Rectifier TEST 17 - CHECK BATTERY CHARGEWINDINGS / BATTERY CHARGE RESISTOR Section DIAGNOSTIC TESTSFigure 7-12.– Harness End of Connector TEST 19- TEST PRIMER SWITCHFigure 7-11.– Primer Switch TEST 18 - TRY CRANKING THE ENGINEFigure 7-14.– Electric Fuel Pump TEST 20- CHECK FUEL PUMPFigure 7-13.- The LPG Fuel Solenoid FS Section DIAGNOSTIC TESTSTEST 21- CHECK 7.5 AMP FUSE TEST 22- CHECK BATTERY & CABLESTEST 23- CHECK POWER SUPPLY TO CIRCUIT BOARD Figure 7-15.– Harness to Fuel PumpFigure 7-18.– Test 24, Step TEST 24 - CHECK START-STOPSWITCHFigure 7-17.- Start-StopSwitch Section DIAGNOSTIC TESTSFigure 7-19.– Starter Contactor Relay TEST 25 - CHECK POWER SUPPLY TO WIRETEST 26- CHECK STARTER CONTACTOR RELAY Section DIAGNOSTIC TESTSFigure 7-20.– The Starter Contactor SC TEST 26A - CHECK STARTER CONTACTORTEST 27 - CHECK STARTER MOTOR STEP 1 TEST POINTFigure 7-22.- Check Pinion Gear Operation Figure 7-21.- Starter Motor SMSection DIAGNOSTIC TESTS Figure 7-24.– Tachometer Figure 7-26.– Testing Starter Motor PerformanceTEST 28- CHECK FUEL SUPPLY Section DIAGNOSTIC TESTSFigure 7-27- Typical Propane Gas Fuel System Figure 7-28– LP Gas Carburetion DiagramSection DIAGNOSTIC TESTS Figure 7-30.– The 4-tabConnector TEST 29 - CHECK WIRE 14 POWER SUPPLYTEST 30 - CHECK WIRE Figure 7-29.– Fuel RegulatorTEST 32 - CHECK IGNITION SPARK Figure 7-31.– Remote Harness ConnectorTEST 31 - CHECK FUEL SOLENOID GASOLINE MODELS Section DIAGNOSTIC TESTSFigure 7-34.- Cylinder Balance Test Figure 7-32.– Testing Ignition SystemFigure 7-33.– Checking Engine Miss Section DIAGNOSTIC TESTSFigure 7-36.– Ignition Magneto Assembly TEST 34 - CHECK AND ADJUST IGNITION MAGNETOSFigure 7-35– Setting Spark Plug Gap TEST 33 - CHECK SPARK PLUGSFigure 7-38.– Engine Ground Harness Figure 7-37.– Setting Ignition MagnetoArmature Air Gap Figure 7-39.– Diode Failure DiagnosisFigure 7-40.- Engine Ground Harness Test Points TEST 35 - CHECK VALVE ADJUSTMENTFigure 7-41– Adjusting Valve Clearance Section DIAGNOSTIC TESTSFigure 7-42- Tightening the Jam Nut TEST 36 - CHECK CARBURETIONTEST 37 - CHECK CHOKE SOLENOID Section DIAGNOSTIC TESTSFigure 7-45.– Automatic Choke Assembly Figure 7-43.- ConnectorFigure 7-44.– Exploded View of Choke Assembly Section DIAGNOSTIC TESTSTEST 38 - CHECK ENGINE / CYLINDER LEAK DOWN TEST / COMPRESSION TESTSection DIAGNOSTIC TESTS Figure 7-46.– Oil Pressure Switch TEST 39 - CHECK OIL PRESSURE SWITCHTEST 40 - TEST OIL TEMPERATURE SWITCH Figure 7-47.– Oil Temperature SwitchTEST 42 - CHECK LPG FUEL SOLENOID Figure 7-48.– Testing Oil Temperature SwitchTEST 41 - TEST CHOKE HEATER Section DIAGNOSTIC TESTSFigure 7-49.– Fuel Solenoid Section DIAGNOSTIC TESTSSection ASSEMBLY MAJOR DISASSEMBLYFigure 8-1.– Drive Belt Tension Section ASSEMBLYSection ASSEMBLY 10.Remove blower housingNOTES PageSection Exploded Views / Part Numbers Base & Pulley – Drawing No. 0E1323-APART NO. QTY Section Exploded Views / Part NumbersITEM DESCRIPTIONSection Exploded Views / Part Numbers Enclosure – Drawing No. 0E1011-BITEM SectionExploded Views / Part Numbers PART NOSection Exploded Views / Part Numbers Sheet Metal – Drawing No. 0E1012-ESection Exploded Views / Part Numbers ITEMSection Exploded Views / Part Numbers Control Panel - Drawing No. 0E1013-ASection Exploded Views / Part Numbers 0C2375Section Exploded Views / Part Numbers 760 V-TwinEngine – Drawing No. 0E1014-BSection Exploded Views / Part Numbers 0C5730ASection Exploded Views / Part Numbers LP Regulator - Drawing No. 0E1530Exploded Views / Part Numbers Section0D5694 Section SPECIFICATIONS & CHARTS NOMINAL RESISTANCES OF GENERATOR WINDINGS AT 68F SPECIFICATIONS & CHARTSGENERATOR SPECIFICATIONS SectionTRIM TORQUE REQUIREMENTS ENGINE SPEEDS AND VOLTAGE SPECIFICATIONSLONG BLOCK TORQUE REQUIREMENTS RV TORQUE REQUIREMENTSNOTES PageSection ELECTRICAL DATA Section ELECTRICAL DATA PageP/N OE7225 REV O PO BOX 297 WHITEWATER, WIPRINTED IN THE USA/9.03