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Generac Power Systems 941-2 Part Engine Mechanical, GENERAL INFORMATION 2.2 VALVE TRAIN, Section

Models: 941-2 940-2

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PART 2

ENGINE

MECHANICAL

COMPUTER

CONTROLLED

VARIABLE

SPEED RV

GENERATORS

Series Impact 36 Plus

SECTION

TITLE

2.1GENERAL INFORMATION

2.2VALVE TRAIN

2.3PISTON, RINGS, CONNECTING ROD

2.4CRANKSHAFT & CAMSHAFT

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Generac Power Systems 941-2 Part Engine Mechanical, GENERAL INFORMATION 2.2 VALVE TRAIN, Series Impact 36 Plus, Section

Contents

P. O. Box 297 Whitewater, WI Models 940-2SERVICE MANUAL SERIES IMPACT 36 PLUSNOTICE TO USERS OF THIS MANUAL SAFETYREPLACEMENT PARTS SPECIFICATIONS & CHARTS SERVICE MANUALTABLE OF CONTENTS TROUBLESHOOTINGPage Series Impact 36 Plus COMPONENTS TESTINGPART GENERAL INFORMATION COMPUTER CONTROLLED VARIABLE SPEED RV GENERATORSPage ELECTROMAGNETIC INDUCTION Section GENERATOR FUNDAMENTALSMAGNETISM ELECTROMAGNETIC FIELDSFigure 5. Alternating Current Sine Wave ALTERNATING CURRENTELECTRICAL UNITS Figure 4. Operation of a Simple GeneratorAMPERES = VOLTSOHMS OHMS LAWREACTANCE IN AC CIRCUITS Figure 6. Electrical UnitsCAPACITIVE REACTANCE Figure 10. Block Diagram of the Impact 36 Plus SystemFigure 9. Capacitive Reactance Section GENERATOR FUNDAMENTALSSection GENERATOR FUNDAMENTALS WHY VARIABLE SPEED CONTROL?Page Section GENERATOR FUNDAMENTALSINTRODUCTION UPPER FAN HOUSINGFigure 2 Permanent Magnet Rotor Assembly Section MAJOR GENERATOR COMPONENTSSTEPPER MOTOR STATOR ASSEMBLYROTOR HUB STATOR RETAINING RINGPage Figure 5. Schematic- Stator WindingsSection MAJOR GENERATOR COMPONENTS Page Section MAJOR GENERATOR COMPONENTSOPERATIONAL DESCRIPTION Figure 1. Block Diagram- A Generator SystemSection OPERATIONAL ANALYSIS GENERALSection OPERATIONAL ANALYSIS OPERATIONAL DESCRIPTION CONTINUEDINSULATION RESISTANCE TESTERS CAUTION! When using a Megohmmeter orSection INSULATION RESISTANCE DIRT AND MOISTURERESULTS OF TESTS CLEANING THE GENERATORTEST ALL STATOR WINDINGS TO GROUND TEST FOR SHORTS BETWEEN WINDINGSCAUTION! Some generators use epoxy or Figure 3. Schematic - Stator WindingsDRYING THE GENERATOR DANGER! DO NOT WORK WITH SOLVENTSPage Section INSULATION RESISTANCEINTRODUCTION Section COMPONENTS TESTINGFigure 1. Stator Leads STATOR ASSEMBLYSection COMPONENTS TESTING STATOR ASSEMBLY CONTINUEDFigure 2. Schematic- Stator Windings Section COMPONENTS TESTING TESTING THE BATTERY CHARGE CIRCUITFigure 3. Battery Charge Windings and Rectifier Figure 4. Battery Charge CircuitPage Section COMPONENTS TESTINGFigure 1. Exploded View of Control Panel Section CONTROL PANELCONSTRUCTION COMPONENTSPage Section CONTROL PANELGENERAL Section SHEET METALImpact Plus Generator TO CARBURETOR EXPLODED VIEW OF SHEET METAL GASOLINE UNITSSection SHEET METAL PageDESCRIPTION PARTS LIST FOR SHEET METAL GASOLINE UNITSSection SHEET METAL DESCRIPTIONPage EXPLODED VIEW OF SHEET METAL LP UNITSSection SHEET METAL DESCRIPTION PARTS LIST FOR SHEET METAL GASOLINE UNITSSection SHEET METAL DESCRIPTIONPage Section SHEET METALCOMPUTER CONTROLLED VARIABLE SPEED RV GENERATORS 2.3 PISTON, RINGS, CONNECTING ROD 2.4 CRANKSHAFT & CAMSHAFTPART ENGINE MECHANICAL 2.1 GENERAL INFORMATION 2.2 VALVE TRAINPage Figure 1. Intake Stroke Figure 2. Compression Stroke Figure 3. Power Stroke Figure 4. Exhaust StrokeSection GENERAL INFORMATION 4-CYCLE ENGINE THEORYNOTE DO NOT MIX OIL WITH THE GASOLINE RECOMMENDED FUELSRECOMMENDED ENGINE OIL NOTE DO NOT USE GASOLINE CONTAINING METHANOLSection GENERAL INFORMATION THE UNIT IS NOW READY FOR SERVICESTORAGE INSTRUCTIONS ENGINE TUNE-UPDESCRIPTION NOTE 1- Item 36 Includes valve seats and guidesSection GENERAL INFORMATION EXPLODED VIEW OF ENGINE LONG BLOCKFigure 1. Valve Train Components Section VALVE TRAINVALVE TRAIN COMPONENTS VALVE COMPONENTS REMOVALFigure 5. Removal of Valve Spring VALVE SERVICEDANGER! ALWAYS WEAR SAFETY GLASSES WHEN REMOVING THE VALVE SPRINGS Figure 4. Cylinder Head RemovalFigure 10. Valve Tappet VALVE COMPONENTS INSTALLATIONFigure 11. Installation of Intake and Exhaust Valves Figure 8. Valve GuidesFigure 14. Install Rocker Arm & Pivot Ball stud VALVE COMPONENTS INSTALLATION CONTINUEDADJUSTING VALVE CLEARANCE Figure 12. Installing Valve Spring WashersFigure 17. Tightening Pivot Ball Jam Nut ROCKER ARM COVER INSTALLATIONFigure 16. Adjusting Valve Clearance Figure 18. Rocker Arm Cover InstallationPage Section VALVE TRAINPRIOR TO REMOVAL Section PISTON, RINGS, CONNECTING RODFigure 1. Piston, Rings and Connecting Rod OVERSIZE PISTON & RINGSFigure 6. Ring to Groove Side Clearance PISTON RINGSFigure 4. Piston Minor Diameter Figure 5. Piston Major DiameterFigure 7. Ring Locations in Piston Grooves CONNECTING RODASSEMBLY AND INSTALLATION Figure 9. Connecting RodSection PISTON, RINGS, CONNECTING ROD CYLINDER SERVICEFigure 10. Match Marks on Rod and Cap CRANKSHAFT REMOVAL Section CRANKSHAFT AND CAMSHAFTCRANKCASE COVER REMOVAL CAMSHAFT REMOVALFigure 5. Points to Check on Crankshaft CAMSHAFT INSPECTIONCRANKSHAFT INSPECTION Figure 4. Points to Check on CamshaftFigure 6. Bearing Bore in Crankcase Cover INSTALLING THE CRANKSHAFTINSTALLING THE CAMSHAFT COMPRESSION RELEASE MECHANISMPage Figure 9. Timing Mark on Crankshaft GearFigure 10. Alignment of Timing Marks Section CRANKSHAFT AND CAMSHAFTFILTER & FUEL PUMP AIR CLEANER & AIR INTAKEPART GASOLINE FUEL SYSTEM INTRODUCTION TO FUEL SYSTEMPage DANGER! ATTEMPTING TO WELD OR BRAZE Section INTRODUCTION TO FUEL SYSTEMRECOMMENDED FUEL EVAPORATION CONTROL SYSTEMSPage Figure 2. Typical Gasoline Fuel SystemSection INTRODUCTION TO FUEL SYSTEM AIR INTAKE Section AIR CLEANER AND INTAKEAIR CLEANER Figure 1. Engine Air CleanerPage Section AIR CLEANER AND INTAKEFigure 1. Fuel Filter Typical Section FUEL FILTER AND FUEL PUMPFUEL FILTER FUEL PUMPPage Section FUEL FILTER AND FUEL PUMPCARBURETOR OPERATION Section CARBURETORGENERAL INFORMATION DESCRIPTIONSection CARBURETOR CARBURETOR DISASSEMBLYCLEANING AND INSPECTION Figure 3. Carburetor Exploded ViewENGINE SPEED ADJUSTMENTTHROTTLE LINKAGE ADJUSTMENT Figure 5. Adjusting Throttle LinkagePage Figure 6. Carburetor RemovalSection CARBURETOR OPERATION OPERATIONAL CHECK AND ADJUSTMENTFigure 2. Choke Adjustment Section AUTOMATIC CHOKEPage Section AUTOMATIC CHOKEFigure 1. Speed Control System STEPPER MOTOR PROBLEMSSection SPEED CONTROL SYSTEM A6060 CIRCUIT BOARDSection SPEED CONTROL SYSTEM TESTING THE STEPPER MOTORFigure 2. The Stepper Motor Connector Figure 3. The Stepper Motor 4.3 CARBURETOR Air Cleaner & Air Intake Section Speed Control System SectionPART GASEOUS FUEL SYSTEM 4.1 INTRODUCTION TO FUEL SYSTEM 4.2 SHUTOFF VALVE & REGULATORPage IMPORTANT CONSIDERATIONS ADVANTAGES OF GASEOUS FUELSFUEL SYSTEM COMPONENTS VAPOR WITHDRAWALFigure 1. A Typical LP Gas Fuel System FUEL SUPPLY LINESEXCESS FLOW VALVE IMPORTANT CONSIDERATIONS CONTINUEDDANGER! DO NOT USE FLAME TO CHECK LEAKAGE TESTINGFigure 2. Gas Carburetion Diagram GASEOUS CARBURETIONPage Section INTRODUCTION TO FUEL SYSTEMSection SHUTOFF VALVE AND REGULATOR ADJUSTMENTSTESTING THE FUEL LOCKOFF SOLENOID DANGER! DO NOT ATTEMPT TO ADJUSTRESULTS OF TEST If battery voltage is Indicated but the solenoid does NOT enerIf battery voltage is NOT Indicated, a problem exists In the DC Section SHUTOFF VALVE AND REGULATORFigure 1. LP Gas Carburetor CARBURETOR ADJUSTMENTDISASSEMBLY AND REASSEMBLY CARBURETIONPage Section CARBURETORSeries Impact 36 Plus PART ENGINE OIL COOLING SYSTEM5.1 ENGINE OIL SYSTEM 5.2 ENGINE COOLING SYSTEM COMPUTER CONTROLLED VARIABLE SPEED RV GENERATORSPage OIL PUMP Figure 1. Oil System DiagramSection ENGINE OIL SYSTEM INTRODUCTION TO OIL SYSTEMPRESSURE RELIEF VALVE BREATHER ASSEMBLYOIL PUMP CONTINUED CRANKSHAFT OIL SEALSFigure 7. Oil Filter Support Figure 6. Breather AssemblyOIL SUMP OIL FILTER SUPPORTPage Section ENGINE OIL SYSTEMFigure 1 - Air Flow Through Engine-Generator Section ENGINE COOLING SYSTEMGENERATOR AIR FLOW COOLING AIR INLET OPENINGSINVERTER LOCATION TESTING THE INSTALLATIONCAUTION Do not install the inverter in the COMPENSATING FOR RESTRICTIONSA6060 CIRCUIT BOARD ENGINE SHUTDOWN FEATURESPART ENGINE ELECTRICAL SYSTEM ENGINE DC CONTROL SYSTEMPage GENERAL Figure 1. Schematic- Engine DC Control SystemSection ENGINE DC CONTROL SYSTEM BOARD HOW IT WORKSNOTE Also see Section 3.5, AUTOMATIC CHOKE and Section 6.2, A6060 CIRCUITSection 6.2 A6060 CIRCUIT BOARD WIREbattery is connected NOTE 1 - See SHUTDOWN FEATURES” In Section 6.5 PageCIRCUIT BOARD CONNECTIONS CONTINUED Section A6060 CIRCUIT BOARDCABLE LENGTH BATTERYFigure 1. Schematic - Cranking Circuit Section ENGINE CRANKING SYSTEMSection ENGINE CRANKING SYSTEM BATTERY CONTINUEDSTART-RUN-STOP SWITCH SW1 STARTER CONTACTORSection ENGINE CRANKING SYSTEM STARTER MOTORFigure 3. Starter Contactor Figure 4. Starter MotorPage Section ENGINE CRANKING SYSTEMSection ENGINE IGNITION SYSTEM IGNITION CAGE ASSEMBLYFigure 1. Ignition Cage Assembly Figure 3. Ignition Sensor SchematicIGNITION MODULE CONTINUED TESTING THE SYSTEMFigure 7. Ignition System Diagram Figure 6. Setting Spark Plug GapFigure 9. Checking Engine Miss Figure 8. Testing for SparkWarning! Do NOT use a screwdriver to test for spark. Personal injury or damage to equip- ment may resultNote Only one spark should be observed upon initial cranking TESTING THE SYSTEM CONTINUEDFigure 12. Testing Ignition Sensor Figure 13. Testing Ignition Coil Figure 14. Testing Ignition ModuleFigure 3. Testing the Oil Temperature Switch Section SHUTDOWN FEATURESOIL PRESSURE SWITCH OIL TEMPERATURE SWITCHSection SHUTDOWN FEATURES ADDITIONAL SHUTDOWN FEATURESGENERAL Section OPTIONAL REMOTE PANELFigure 1. Remote Panel Plug-In Receptacle Figure 2. Optional Remote Panel Models 004057 andPage Section OPTIONAL REMOTE PANELCOMPUTER CONTROLLED VARIABLE SPEED RV GENERATORS PART TROUBLE SHOOTING7.2 ENGINE DC CONTROL SYSTEM/ AC TROUBLESHOOTING 7.1 GENERATOR & SPEED CONTROLPage Page TROUBLESHOOTING REFERENCE CHARTSection GENERATOR & SPEED CONTROL SYSTEM Page Section GENERATOR & SPEED CONTROL SYSTEMINTRODUCTION Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGPROBLEM 1- PRIMING FUNCTION DOES NOT WORK Page PROBLEM 2 - ENGINE WILL NOT CRANKPROBLEM 3 - ENGINE CRANKS BUT WILL NOT START Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PROBLEM 3 - ENGINE CRANKS BUT WILL NOT START CONTINUEDPage PROBLEM 4 - ENGINE STARTS HARD AND RUNS ROUGHSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING Page PROBLEM 5 - ENGINE STARTS THEN SHUTS DOWN AFTER A FEW SECONDSSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING SHUTS DOWN TEST TEST INVERTER Pg FAIL REPLACE INVERTERPage PROBLEM 6 - GENERATOR DOESN’T PULL FULL LOADPROBLEM 7 - GENERATOR CIRCUIT BREAKER TRIPS / NO AC VOLTAGE Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGPage PROBLEM 8 - ENGINE SHUTS DOWN UNDER LOADPROBLEM 9 - GENERATOR LOSES AC POWER THEN SHUTS DOWN Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGPage PROBLEM 10 - NO AC OUTPUTSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING 12-WIREPage PROBLEM 10 - NO AC OUTPUT CONTINUEDSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING TEST 1- CHECK 7.5 AMP FUSE TEST 3- CHECK POWER TO FUEL PUMPTEST 2- CHECK POWER TO PRIMER SWITCH Figure 2. Primer SwitchTEST 4- CHECK BATTERY/BATTERY CIRCUIT TEST 6- TEST PRIMER SWITCHTEST 7- CHECK WIRE 14A TO FUEL PUMP TEST 8- CHECK POWER SUPPLY TO STARTER MOTORSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING TEST 9- CHECK WIRE 56 POWER TO STARTER CONTACTORTEST 10- CHECK A6060 CIRCUIT BOARD POWER SUPPLY Figure 5. Starter ContactorTEST 13- CHECK FUEL SUPPLY TEST 12- TEST START-STOP SWITCHFigure 7. Start-Stop Switch TEST 11- TEST STARTER CONTACTORTEST 18- CHECK IGNITION SENSOR TEST 21 - CHECK A6060 CIRCUIT BOARD OUTPUT TO WIRETEST 17- CHECK IGNITION POWER SUPPLY Figure 9. Ignition Module & 4-Tab ConnectorFigure 10. Receptacle J2 TEST 23- CHECK CARBURETIONTEST 22-TEST AUTOMATIC CHOKE TEST 24- CHECK ENGINETEST 28 - DC LINK VOLTAGE TEST TEST 27- TEST OIL TEMPERATURE SWITCHTEST 26- TEST OIL PRESSURE SWITCH Note Cap the DC Link wires with a wire nut for safetyFigure 10 Free End of 12 Position Harness TEST 30 - 12 POSITION HARNESS SIGNALS TESTTEST 29 - 12 POSITION HARNESS CONTINUITY TEST Note Fluke 87 true RMS meter used in testTEST 31 - STATIC TESTS ON INVERTER STATOR TESTS TEST 32 - POWER SUPPLY WINDING TESTFigure 11. 12 Position Connector on Inverter Pin 4 Wire #14Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING TEST 36 - AC POWER WINDING TEST AC1/AC2/SL1/SL2TEST 34 -STATOR RESISTANCE VALUES TEST 35 - BRIDGE RECTIFIER TESTPage Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGWiring Diagram PART SPECIFICATIONS AND CHARTSGeneral Specifications Electrical SchematicPage LOAD % ENGINE SPEEDS AND VOLTAGE SPECIFICATIONSPart NOMINAL RESISTANCES OF GENERATOR WINDINGSPage Part SPECIFICATIONS & CHARTSELECTRICAL SCHEMATIC DRAWING NO. 0D4947-B 1 OFPage WIRING DIAGRAM DRAWING NO. 0D4947-BPart SPECIFICATIONS & CHARTS 2 OFPart SPECIFICATIONS & CHARTS GENERAL SPECIFICATIONSMODEL GV-220Later model small frame GN engines have no crankshaft sleeve bearing SPECIFICATIONS & CHARTSCRANKCASE ASSEMBLY CRANKCASE COVER ASSEMBLYPart SPECIFICATIONS & CHARTS CONNECTING ROD ASSEMBLYCRANKSHAFT PISTONMODEL PISTON CONTINUEDPart SPECIFICATIONS & CHARTS Part SPECIFICATIONS & CHARTS CAMSHAFT ASSEMBLYOIL PUMP NOTE 2 Measure pump tip clearance on shaft in crankcase coverMODEL SPECIFICATIONS & CHARTSPart MODELPage MAJOR FEATURES AND DIMENSIONS GENERATORPart SPECIFICATIONS & CHARTS Page MAJOR FEATURES AND DIMENSIONS INVERTERPart SPECIFICATIONS & CHARTS