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

Generac Power Systems 941-2, 940-2 Section SHEET METAL, Impact Plus Generator, General

Models: 941-2 940-2

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Section 1.7

SHEET METAL

GENERAL

See "Exploded View of Sheet Metal" on next page. A DIVIDER PLATE (Item 1) separates the AC generator components from the engine. The engine Itself is enclosed by a BASE HOUSING WRAPPER (Item 4), a FRAME (Item 24), and a BELLY PAN (Item 23). These components are sealed by means of rubber SEALS (Items 3), to prevent

The LOWER FAN attaches to the engine shaft and is enclosed in a LOWER FAN HOUSING (Item 19). Air is drawn Into the enclosed area around the engine and forced out of the LOWER FAN HOUSING.

Removal of sheet metal will be necessary for many repairs and for replacement of most parts.

Impact Plus Generator

Page 1.7-1

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Generac Power Systems 941-2, 940-2 service manual Section SHEET METAL, Impact Plus Generator, General

Contents

SERVICE MANUAL Models 940-2SERIES IMPACT 36 PLUS P. O. Box 297 Whitewater, WINOTICE TO USERS OF THIS MANUAL SAFETYREPLACEMENT PARTS TABLE OF CONTENTS SERVICE MANUALTROUBLESHOOTING SPECIFICATIONS & CHARTSPage PART GENERAL INFORMATION COMPONENTS TESTINGCOMPUTER CONTROLLED VARIABLE SPEED RV GENERATORS Series Impact 36 PlusPage MAGNETISM Section GENERATOR FUNDAMENTALSELECTROMAGNETIC FIELDS ELECTROMAGNETIC INDUCTIONELECTRICAL UNITS ALTERNATING CURRENTFigure 4. Operation of a Simple Generator Figure 5. Alternating Current Sine WaveREACTANCE IN AC CIRCUITS OHMS LAWFigure 6. Electrical Units AMPERES = VOLTSOHMSFigure 9. Capacitive Reactance Figure 10. Block Diagram of the Impact 36 Plus SystemSection GENERATOR FUNDAMENTALS CAPACITIVE REACTANCESection GENERATOR FUNDAMENTALS WHY VARIABLE SPEED CONTROL?Page Section GENERATOR FUNDAMENTALSFigure 2 Permanent Magnet Rotor Assembly UPPER FAN HOUSINGSection MAJOR GENERATOR COMPONENTS INTRODUCTIONROTOR HUB STATOR ASSEMBLYSTATOR RETAINING RING STEPPER MOTORPage Figure 5. Schematic- Stator WindingsSection MAJOR GENERATOR COMPONENTS Page Section MAJOR GENERATOR COMPONENTSSection OPERATIONAL ANALYSIS Figure 1. Block Diagram- A Generator SystemGENERAL OPERATIONAL DESCRIPTIONSection OPERATIONAL ANALYSIS OPERATIONAL DESCRIPTION CONTINUEDSection INSULATION RESISTANCE CAUTION! When using a Megohmmeter orDIRT AND MOISTURE INSULATION RESISTANCE TESTERSTEST ALL STATOR WINDINGS TO GROUND CLEANING THE GENERATORTEST FOR SHORTS BETWEEN WINDINGS RESULTS OF TESTSDRYING THE GENERATOR Figure 3. Schematic - Stator WindingsDANGER! DO NOT WORK WITH SOLVENTS CAUTION! Some generators use epoxy orPage Section INSULATION RESISTANCEFigure 1. Stator Leads Section COMPONENTS TESTINGSTATOR ASSEMBLY INTRODUCTIONSection COMPONENTS TESTING STATOR ASSEMBLY CONTINUEDFigure 2. Schematic- Stator Windings Figure 3. Battery Charge Windings and Rectifier TESTING THE BATTERY CHARGE CIRCUITFigure 4. Battery Charge Circuit Section COMPONENTS TESTINGPage Section COMPONENTS TESTINGCONSTRUCTION Section CONTROL PANELCOMPONENTS Figure 1. Exploded View of Control PanelPage Section CONTROL PANELGENERAL Section SHEET METALImpact Plus Generator Section SHEET METAL EXPLODED VIEW OF SHEET METAL GASOLINE UNITSPage TO CARBURETORSection SHEET METAL PARTS LIST FOR SHEET METAL GASOLINE UNITSDESCRIPTION DESCRIPTIONPage EXPLODED VIEW OF SHEET METAL LP UNITSSection SHEET METAL Section SHEET METAL PARTS LIST FOR SHEET METAL GASOLINE UNITSDESCRIPTION DESCRIPTIONPage Section SHEET METALPART ENGINE MECHANICAL 2.3 PISTON, RINGS, CONNECTING ROD 2.4 CRANKSHAFT & CAMSHAFT2.1 GENERAL INFORMATION 2.2 VALVE TRAIN COMPUTER CONTROLLED VARIABLE SPEED RV GENERATORSPage Section GENERAL INFORMATION Figure 3. Power Stroke Figure 4. Exhaust Stroke4-CYCLE ENGINE THEORY Figure 1. Intake Stroke Figure 2. Compression StrokeRECOMMENDED ENGINE OIL RECOMMENDED FUELSNOTE DO NOT USE GASOLINE CONTAINING METHANOL NOTE DO NOT MIX OIL WITH THE GASOLINESTORAGE INSTRUCTIONS THE UNIT IS NOW READY FOR SERVICEENGINE TUNE-UP Section GENERAL INFORMATIONSection GENERAL INFORMATION NOTE 1- Item 36 Includes valve seats and guidesEXPLODED VIEW OF ENGINE LONG BLOCK DESCRIPTIONVALVE TRAIN COMPONENTS Section VALVE TRAINVALVE COMPONENTS REMOVAL Figure 1. Valve Train ComponentsDANGER! ALWAYS WEAR SAFETY GLASSES WHEN REMOVING THE VALVE SPRINGS VALVE SERVICEFigure 4. Cylinder Head Removal Figure 5. Removal of Valve SpringFigure 11. Installation of Intake and Exhaust Valves VALVE COMPONENTS INSTALLATIONFigure 8. Valve Guides Figure 10. Valve TappetADJUSTING VALVE CLEARANCE VALVE COMPONENTS INSTALLATION CONTINUEDFigure 12. Installing Valve Spring Washers Figure 14. Install Rocker Arm & Pivot Ball studFigure 16. Adjusting Valve Clearance ROCKER ARM COVER INSTALLATIONFigure 18. Rocker Arm Cover Installation Figure 17. Tightening Pivot Ball Jam NutPage Section VALVE TRAINFigure 1. Piston, Rings and Connecting Rod Section PISTON, RINGS, CONNECTING RODOVERSIZE PISTON & RINGS PRIOR TO REMOVALFigure 4. Piston Minor Diameter PISTON RINGSFigure 5. Piston Major Diameter Figure 6. Ring to Groove Side ClearanceASSEMBLY AND INSTALLATION CONNECTING RODFigure 9. Connecting Rod Figure 7. Ring Locations in Piston GroovesSection PISTON, RINGS, CONNECTING ROD CYLINDER SERVICEFigure 10. Match Marks on Rod and Cap CRANKCASE COVER REMOVAL Section CRANKSHAFT AND CAMSHAFTCAMSHAFT REMOVAL CRANKSHAFT REMOVALCRANKSHAFT INSPECTION CAMSHAFT INSPECTIONFigure 4. Points to Check on Camshaft Figure 5. Points to Check on CrankshaftINSTALLING THE CAMSHAFT INSTALLING THE CRANKSHAFTCOMPRESSION RELEASE MECHANISM Figure 6. Bearing Bore in Crankcase CoverFigure 10. Alignment of Timing Marks Figure 9. Timing Mark on Crankshaft GearSection CRANKSHAFT AND CAMSHAFT PagePART GASOLINE FUEL SYSTEM AIR CLEANER & AIR INTAKEINTRODUCTION TO FUEL SYSTEM FILTER & FUEL PUMPPage RECOMMENDED FUEL Section INTRODUCTION TO FUEL SYSTEMEVAPORATION CONTROL SYSTEMS DANGER! ATTEMPTING TO WELD OR BRAZEPage Figure 2. Typical Gasoline Fuel SystemSection INTRODUCTION TO FUEL SYSTEM AIR CLEANER Section AIR CLEANER AND INTAKEFigure 1. Engine Air Cleaner AIR INTAKEPage Section AIR CLEANER AND INTAKEFUEL FILTER Section FUEL FILTER AND FUEL PUMPFUEL PUMP Figure 1. Fuel Filter TypicalPage Section FUEL FILTER AND FUEL PUMPGENERAL INFORMATION Section CARBURETORDESCRIPTION CARBURETOR OPERATIONCLEANING AND INSPECTION CARBURETOR DISASSEMBLYFigure 3. Carburetor Exploded View Section CARBURETORTHROTTLE LINKAGE ADJUSTMENT ADJUSTMENTFigure 5. Adjusting Throttle Linkage ENGINE SPEEDPage Figure 6. Carburetor RemovalSection CARBURETOR Figure 2. Choke Adjustment OPERATIONAL CHECK AND ADJUSTMENTSection AUTOMATIC CHOKE OPERATIONPage Section AUTOMATIC CHOKESection SPEED CONTROL SYSTEM STEPPER MOTOR PROBLEMSA6060 CIRCUIT BOARD Figure 1. Speed Control SystemSection SPEED CONTROL SYSTEM TESTING THE STEPPER MOTORFigure 2. The Stepper Motor Connector Figure 3. The Stepper Motor PART GASEOUS FUEL SYSTEM Air Cleaner & Air Intake Section Speed Control System Section4.1 INTRODUCTION TO FUEL SYSTEM 4.2 SHUTOFF VALVE & REGULATOR 4.3 CARBURETORPage FUEL SYSTEM COMPONENTS ADVANTAGES OF GASEOUS FUELSVAPOR WITHDRAWAL IMPORTANT CONSIDERATIONSEXCESS FLOW VALVE FUEL SUPPLY LINESIMPORTANT CONSIDERATIONS CONTINUED Figure 1. A Typical LP Gas Fuel SystemFigure 2. Gas Carburetion Diagram LEAKAGE TESTINGGASEOUS CARBURETION DANGER! DO NOT USE FLAME TO CHECKPage Section INTRODUCTION TO FUEL SYSTEMTESTING THE FUEL LOCKOFF SOLENOID ADJUSTMENTSDANGER! DO NOT ATTEMPT TO ADJUST Section SHUTOFF VALVE AND REGULATORIf battery voltage is NOT Indicated, a problem exists In the DC If battery voltage is Indicated but the solenoid does NOT enerSection SHUTOFF VALVE AND REGULATOR RESULTS OF TESTDISASSEMBLY AND REASSEMBLY CARBURETOR ADJUSTMENTCARBURETION Figure 1. LP Gas CarburetorPage Section CARBURETOR5.1 ENGINE OIL SYSTEM 5.2 ENGINE COOLING SYSTEM PART ENGINE OIL COOLING SYSTEMCOMPUTER CONTROLLED VARIABLE SPEED RV GENERATORS Series Impact 36 PlusPage Section ENGINE OIL SYSTEM Figure 1. Oil System DiagramINTRODUCTION TO OIL SYSTEM OIL PUMPOIL PUMP CONTINUED BREATHER ASSEMBLYCRANKSHAFT OIL SEALS PRESSURE RELIEF VALVEOIL SUMP Figure 6. Breather AssemblyOIL FILTER SUPPORT Figure 7. Oil Filter SupportPage Section ENGINE OIL SYSTEMGENERATOR AIR FLOW Section ENGINE COOLING SYSTEMCOOLING AIR INLET OPENINGS Figure 1 - Air Flow Through Engine-GeneratorCAUTION Do not install the inverter in the TESTING THE INSTALLATIONCOMPENSATING FOR RESTRICTIONS INVERTER LOCATIONPART ENGINE ELECTRICAL SYSTEM ENGINE SHUTDOWN FEATURESENGINE DC CONTROL SYSTEM A6060 CIRCUIT BOARDPage GENERAL Figure 1. Schematic- Engine DC Control SystemSection ENGINE DC CONTROL SYSTEM NOTE Also see Section 3.5, AUTOMATIC HOW IT WORKSCHOKE and Section 6.2, A6060 CIRCUIT BOARDbattery is connected WIRENOTE 1 - See SHUTDOWN FEATURES” In Section 6.5 Page Section 6.2 A6060 CIRCUIT BOARDCIRCUIT BOARD CONNECTIONS CONTINUED Section A6060 CIRCUIT BOARDFigure 1. Schematic - Cranking Circuit BATTERYSection ENGINE CRANKING SYSTEM CABLE LENGTHSTART-RUN-STOP SWITCH SW1 BATTERY CONTINUEDSTARTER CONTACTOR Section ENGINE CRANKING SYSTEMFigure 3. Starter Contactor STARTER MOTORFigure 4. Starter Motor Section ENGINE CRANKING SYSTEMPage Section ENGINE CRANKING SYSTEMFigure 1. Ignition Cage Assembly IGNITION CAGE ASSEMBLYFigure 3. Ignition Sensor Schematic Section ENGINE IGNITION SYSTEMFigure 7. Ignition System Diagram TESTING THE SYSTEMFigure 6. Setting Spark Plug Gap IGNITION MODULE CONTINUEDWarning! Do NOT use a screwdriver to test for Figure 8. Testing for Sparkspark. Personal injury or damage to equip- ment may result Figure 9. Checking Engine MissFigure 12. Testing Ignition Sensor TESTING THE SYSTEM CONTINUEDFigure 13. Testing Ignition Coil Figure 14. Testing Ignition Module Note Only one spark should be observed upon initial crankingOIL PRESSURE SWITCH Section SHUTDOWN FEATURESOIL TEMPERATURE SWITCH Figure 3. Testing the Oil Temperature SwitchSection SHUTDOWN FEATURES ADDITIONAL SHUTDOWN FEATURESFigure 1. Remote Panel Plug-In Receptacle Section OPTIONAL REMOTE PANELFigure 2. Optional Remote Panel Models 004057 and GENERALPage Section OPTIONAL REMOTE PANEL7.2 ENGINE DC CONTROL SYSTEM/ AC TROUBLESHOOTING PART TROUBLE SHOOTING7.1 GENERATOR & SPEED CONTROL COMPUTER CONTROLLED VARIABLE SPEED RV GENERATORSPage 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 PROBLEM 3 - ENGINE CRANKS BUT WILL NOT START PROBLEM 2 - ENGINE WILL NOT CRANKSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PageSection 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 Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PROBLEM 5 - ENGINE STARTS THEN SHUTS DOWN AFTER A FEW SECONDSSHUTS DOWN TEST TEST INVERTER Pg FAIL REPLACE INVERTER PagePROBLEM 7 - GENERATOR CIRCUIT BREAKER TRIPS / NO AC VOLTAGE PROBLEM 6 - GENERATOR DOESN’T PULL FULL LOADSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PagePROBLEM 9 - GENERATOR LOSES AC POWER THEN SHUTS DOWN PROBLEM 8 - ENGINE SHUTS DOWN UNDER LOADSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PageSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PROBLEM 10 - NO AC OUTPUT12-WIRE PagePage PROBLEM 10 - NO AC OUTPUT CONTINUEDSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING TEST 2- CHECK POWER TO PRIMER SWITCH TEST 3- CHECK POWER TO FUEL PUMPFigure 2. Primer Switch TEST 1- CHECK 7.5 AMP FUSETEST 7- CHECK WIRE 14A TO FUEL PUMP TEST 6- TEST PRIMER SWITCHTEST 8- CHECK POWER SUPPLY TO STARTER MOTOR TEST 4- CHECK BATTERY/BATTERY CIRCUITTEST 10- CHECK A6060 CIRCUIT BOARD POWER SUPPLY TEST 9- CHECK WIRE 56 POWER TO STARTER CONTACTORFigure 5. Starter Contactor Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGFigure 7. Start-Stop Switch TEST 12- TEST START-STOP SWITCHTEST 11- TEST STARTER CONTACTOR TEST 13- CHECK FUEL SUPPLYTEST 17- CHECK IGNITION POWER SUPPLY TEST 21 - CHECK A6060 CIRCUIT BOARD OUTPUT TO WIREFigure 9. Ignition Module & 4-Tab Connector TEST 18- CHECK IGNITION SENSORTEST 22-TEST AUTOMATIC CHOKE TEST 23- CHECK CARBURETIONTEST 24- CHECK ENGINE Figure 10. Receptacle J2TEST 26- TEST OIL PRESSURE SWITCH TEST 27- TEST OIL TEMPERATURE SWITCHNote Cap the DC Link wires with a wire nut for safety TEST 28 - DC LINK VOLTAGE TESTTEST 29 - 12 POSITION HARNESS CONTINUITY TEST TEST 30 - 12 POSITION HARNESS SIGNALS TESTNote Fluke 87 true RMS meter used in test Figure 10 Free End of 12 Position HarnessFigure 11. 12 Position Connector on Inverter STATOR TESTS TEST 32 - POWER SUPPLY WINDING TESTPin 4 Wire #14 TEST 31 - STATIC TESTS ON INVERTERTEST 34 -STATOR RESISTANCE VALUES TEST 36 - AC POWER WINDING TEST AC1/AC2/SL1/SL2TEST 35 - BRIDGE RECTIFIER TEST Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGPage Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGGeneral Specifications PART SPECIFICATIONS AND CHARTSElectrical Schematic Wiring DiagramPage Part ENGINE SPEEDS AND VOLTAGE SPECIFICATIONSNOMINAL RESISTANCES OF GENERATOR WINDINGS LOAD %ELECTRICAL SCHEMATIC DRAWING NO. 0D4947-B Part SPECIFICATIONS & CHARTS1 OF PagePart SPECIFICATIONS & CHARTS WIRING DIAGRAM DRAWING NO. 0D4947-B2 OF PageMODEL GENERAL SPECIFICATIONSGV-220 Part SPECIFICATIONS & CHARTSCRANKCASE ASSEMBLY SPECIFICATIONS & CHARTSCRANKCASE COVER ASSEMBLY Later model small frame GN engines have no crankshaft sleeve bearingCRANKSHAFT CONNECTING ROD ASSEMBLYPISTON Part SPECIFICATIONS & CHARTSMODEL PISTON CONTINUEDPart SPECIFICATIONS & CHARTS OIL PUMP CAMSHAFT ASSEMBLYNOTE 2 Measure pump tip clearance on shaft in crankcase cover Part SPECIFICATIONS & CHARTSPart SPECIFICATIONS & CHARTSMODEL MODELPage MAJOR FEATURES AND DIMENSIONS GENERATORPart SPECIFICATIONS & CHARTS Page MAJOR FEATURES AND DIMENSIONS INVERTERPart SPECIFICATIONS & CHARTS