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

Generac Power Systems 940-2, 941-2 service manual PROBLEM 2 - ENGINE WILL NOT CRANK, Page

Models: 941-2 940-2

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Section 7.2

ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING

PROBLEM 2 - ENGINE WILL NOT CRANK

PROBLEM 3 - ENGINE CRANKS BUT WILL NOT START

Page 7.2-2

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Generac Power Systems 940-2, 941-2 PROBLEM 2 - ENGINE WILL NOT CRANK, PROBLEM 3 - ENGINE CRANKS BUT WILL NOT START, Page

Contents

Models 940-2 SERVICE MANUALSERIES IMPACT 36 PLUS P. O. Box 297 Whitewater, WIREPLACEMENT PARTS SAFETYNOTICE TO USERS OF THIS MANUAL SERVICE MANUAL TABLE OF CONTENTSTROUBLESHOOTING SPECIFICATIONS & CHARTSPage COMPONENTS TESTING PART GENERAL INFORMATIONCOMPUTER CONTROLLED VARIABLE SPEED RV GENERATORS Series Impact 36 PlusPage Section GENERATOR FUNDAMENTALS MAGNETISMELECTROMAGNETIC FIELDS ELECTROMAGNETIC INDUCTIONALTERNATING CURRENT ELECTRICAL UNITSFigure 4. Operation of a Simple Generator Figure 5. Alternating Current Sine WaveOHMS LAW REACTANCE IN AC CIRCUITSFigure 6. Electrical Units AMPERES = VOLTSOHMSFigure 10. Block Diagram of the Impact 36 Plus System Figure 9. Capacitive ReactanceSection GENERATOR FUNDAMENTALS CAPACITIVE REACTANCEWHY VARIABLE SPEED CONTROL? Section GENERATOR FUNDAMENTALSSection GENERATOR FUNDAMENTALS PageUPPER FAN HOUSING Figure 2 Permanent Magnet Rotor AssemblySection MAJOR GENERATOR COMPONENTS INTRODUCTIONSTATOR ASSEMBLY ROTOR HUBSTATOR RETAINING RING STEPPER MOTORSection MAJOR GENERATOR COMPONENTS Figure 5. Schematic- Stator WindingsPage Section MAJOR GENERATOR COMPONENTS PageFigure 1. Block Diagram- A Generator System Section OPERATIONAL ANALYSISGENERAL OPERATIONAL DESCRIPTIONOPERATIONAL DESCRIPTION CONTINUED Section OPERATIONAL ANALYSISCAUTION! When using a Megohmmeter or Section INSULATION RESISTANCEDIRT AND MOISTURE INSULATION RESISTANCE TESTERSCLEANING THE GENERATOR TEST ALL STATOR WINDINGS TO GROUNDTEST FOR SHORTS BETWEEN WINDINGS RESULTS OF TESTSFigure 3. Schematic - Stator Windings DRYING THE GENERATORDANGER! DO NOT WORK WITH SOLVENTS CAUTION! Some generators use epoxy orSection INSULATION RESISTANCE PageSection COMPONENTS TESTING Figure 1. Stator LeadsSTATOR ASSEMBLY INTRODUCTIONFigure 2. Schematic- Stator Windings STATOR ASSEMBLY CONTINUEDSection COMPONENTS TESTING TESTING THE BATTERY CHARGE CIRCUIT Figure 3. Battery Charge Windings and RectifierFigure 4. Battery Charge Circuit Section COMPONENTS TESTINGSection COMPONENTS TESTING PageSection CONTROL PANEL CONSTRUCTIONCOMPONENTS Figure 1. Exploded View of Control PanelSection CONTROL PANEL PageImpact Plus Generator Section SHEET METALGENERAL EXPLODED VIEW OF SHEET METAL GASOLINE UNITS Section SHEET METALPage TO CARBURETORPARTS LIST FOR SHEET METAL GASOLINE UNITS Section SHEET METALDESCRIPTION DESCRIPTIONSection SHEET METAL EXPLODED VIEW OF SHEET METAL LP UNITSPage PARTS LIST FOR SHEET METAL GASOLINE UNITS Section SHEET METALDESCRIPTION DESCRIPTIONSection SHEET METAL Page2.3 PISTON, RINGS, CONNECTING ROD 2.4 CRANKSHAFT & CAMSHAFT PART ENGINE MECHANICAL2.1 GENERAL INFORMATION 2.2 VALVE TRAIN COMPUTER CONTROLLED VARIABLE SPEED RV GENERATORSPage Figure 3. Power Stroke Figure 4. Exhaust Stroke Section GENERAL INFORMATION4-CYCLE ENGINE THEORY Figure 1. Intake Stroke Figure 2. Compression StrokeRECOMMENDED FUELS RECOMMENDED ENGINE OILNOTE DO NOT USE GASOLINE CONTAINING METHANOL NOTE DO NOT MIX OIL WITH THE GASOLINETHE UNIT IS NOW READY FOR SERVICE STORAGE INSTRUCTIONSENGINE TUNE-UP Section GENERAL INFORMATIONNOTE 1- Item 36 Includes valve seats and guides Section GENERAL INFORMATIONEXPLODED VIEW OF ENGINE LONG BLOCK DESCRIPTIONSection VALVE TRAIN VALVE TRAIN COMPONENTSVALVE COMPONENTS REMOVAL Figure 1. Valve Train ComponentsVALVE SERVICE DANGER! ALWAYS WEAR SAFETY GLASSES WHEN REMOVING THE VALVE SPRINGSFigure 4. Cylinder Head Removal Figure 5. Removal of Valve SpringVALVE COMPONENTS INSTALLATION Figure 11. Installation of Intake and Exhaust ValvesFigure 8. Valve Guides Figure 10. Valve TappetVALVE COMPONENTS INSTALLATION CONTINUED ADJUSTING VALVE CLEARANCEFigure 12. Installing Valve Spring Washers Figure 14. Install Rocker Arm & Pivot Ball studROCKER ARM COVER INSTALLATION Figure 16. Adjusting Valve ClearanceFigure 18. Rocker Arm Cover Installation Figure 17. Tightening Pivot Ball Jam NutSection VALVE TRAIN PageSection PISTON, RINGS, CONNECTING ROD Figure 1. Piston, Rings and Connecting RodOVERSIZE PISTON & RINGS PRIOR TO REMOVALPISTON RINGS Figure 4. Piston Minor DiameterFigure 5. Piston Major Diameter Figure 6. Ring to Groove Side ClearanceCONNECTING ROD ASSEMBLY AND INSTALLATIONFigure 9. Connecting Rod Figure 7. Ring Locations in Piston GroovesFigure 10. Match Marks on Rod and Cap CYLINDER SERVICESection PISTON, RINGS, CONNECTING ROD Section CRANKSHAFT AND CAMSHAFT CRANKCASE COVER REMOVALCAMSHAFT REMOVAL CRANKSHAFT REMOVALCAMSHAFT INSPECTION CRANKSHAFT INSPECTIONFigure 4. Points to Check on Camshaft Figure 5. Points to Check on CrankshaftINSTALLING THE CRANKSHAFT INSTALLING THE CAMSHAFTCOMPRESSION RELEASE MECHANISM Figure 6. Bearing Bore in Crankcase CoverFigure 9. Timing Mark on Crankshaft Gear Figure 10. Alignment of Timing MarksSection CRANKSHAFT AND CAMSHAFT PageAIR CLEANER & AIR INTAKE PART GASOLINE FUEL SYSTEMINTRODUCTION TO FUEL SYSTEM FILTER & FUEL PUMPPage Section INTRODUCTION TO FUEL SYSTEM RECOMMENDED FUELEVAPORATION CONTROL SYSTEMS DANGER! ATTEMPTING TO WELD OR BRAZESection INTRODUCTION TO FUEL SYSTEM Figure 2. Typical Gasoline Fuel SystemPage Section AIR CLEANER AND INTAKE AIR CLEANERFigure 1. Engine Air Cleaner AIR INTAKESection AIR CLEANER AND INTAKE PageSection FUEL FILTER AND FUEL PUMP FUEL FILTERFUEL PUMP Figure 1. Fuel Filter TypicalSection FUEL FILTER AND FUEL PUMP PageSection CARBURETOR GENERAL INFORMATIONDESCRIPTION CARBURETOR OPERATIONCARBURETOR DISASSEMBLY CLEANING AND INSPECTIONFigure 3. Carburetor Exploded View Section CARBURETORADJUSTMENT THROTTLE LINKAGE ADJUSTMENTFigure 5. Adjusting Throttle Linkage ENGINE SPEEDSection CARBURETOR Figure 6. Carburetor RemovalPage OPERATIONAL CHECK AND ADJUSTMENT Figure 2. Choke AdjustmentSection AUTOMATIC CHOKE OPERATIONSection AUTOMATIC CHOKE PageSTEPPER MOTOR PROBLEMS Section SPEED CONTROL SYSTEMA6060 CIRCUIT BOARD Figure 1. Speed Control SystemFigure 2. The Stepper Motor Connector Figure 3. The Stepper Motor TESTING THE STEPPER MOTORSection SPEED CONTROL SYSTEM Air Cleaner & Air Intake Section Speed Control System Section PART GASEOUS FUEL SYSTEM4.1 INTRODUCTION TO FUEL SYSTEM 4.2 SHUTOFF VALVE & REGULATOR 4.3 CARBURETORPage ADVANTAGES OF GASEOUS FUELS FUEL SYSTEM COMPONENTSVAPOR WITHDRAWAL IMPORTANT CONSIDERATIONSFUEL SUPPLY LINES EXCESS FLOW VALVEIMPORTANT CONSIDERATIONS CONTINUED Figure 1. A Typical LP Gas Fuel SystemLEAKAGE TESTING Figure 2. Gas Carburetion DiagramGASEOUS CARBURETION DANGER! DO NOT USE FLAME TO CHECKSection INTRODUCTION TO FUEL SYSTEM PageADJUSTMENTS TESTING THE FUEL LOCKOFF SOLENOIDDANGER! DO NOT ATTEMPT TO ADJUST Section SHUTOFF VALVE AND REGULATORIf battery voltage is Indicated but the solenoid does NOT ener If battery voltage is NOT Indicated, a problem exists In the DCSection SHUTOFF VALVE AND REGULATOR RESULTS OF TESTCARBURETOR ADJUSTMENT DISASSEMBLY AND REASSEMBLYCARBURETION Figure 1. LP Gas CarburetorSection CARBURETOR PagePART ENGINE OIL COOLING SYSTEM 5.1 ENGINE OIL SYSTEM 5.2 ENGINE COOLING SYSTEMCOMPUTER CONTROLLED VARIABLE SPEED RV GENERATORS Series Impact 36 PlusPage Figure 1. Oil System Diagram Section ENGINE OIL SYSTEMINTRODUCTION TO OIL SYSTEM OIL PUMPBREATHER ASSEMBLY OIL PUMP CONTINUEDCRANKSHAFT OIL SEALS PRESSURE RELIEF VALVEFigure 6. Breather Assembly OIL SUMPOIL FILTER SUPPORT Figure 7. Oil Filter SupportSection ENGINE OIL SYSTEM PageSection ENGINE COOLING SYSTEM GENERATOR AIR FLOWCOOLING AIR INLET OPENINGS Figure 1 - Air Flow Through Engine-GeneratorTESTING THE INSTALLATION CAUTION Do not install the inverter in theCOMPENSATING FOR RESTRICTIONS INVERTER LOCATIONENGINE SHUTDOWN FEATURES PART ENGINE ELECTRICAL SYSTEMENGINE DC CONTROL SYSTEM A6060 CIRCUIT BOARDPage Section ENGINE DC CONTROL SYSTEM Figure 1. Schematic- Engine DC Control SystemGENERAL HOW IT WORKS NOTE Also see Section 3.5, AUTOMATICCHOKE and Section 6.2, A6060 CIRCUIT BOARDWIRE battery is connectedNOTE 1 - See SHUTDOWN FEATURES” In Section 6.5 Page Section 6.2 A6060 CIRCUIT BOARDSection A6060 CIRCUIT BOARD CIRCUIT BOARD CONNECTIONS CONTINUEDBATTERY Figure 1. Schematic - Cranking CircuitSection ENGINE CRANKING SYSTEM CABLE LENGTHBATTERY CONTINUED START-RUN-STOP SWITCH SW1STARTER CONTACTOR Section ENGINE CRANKING SYSTEMSTARTER MOTOR Figure 3. Starter ContactorFigure 4. Starter Motor Section ENGINE CRANKING SYSTEMSection ENGINE CRANKING SYSTEM PageIGNITION CAGE ASSEMBLY Figure 1. Ignition Cage AssemblyFigure 3. Ignition Sensor Schematic Section ENGINE IGNITION SYSTEMTESTING THE SYSTEM Figure 7. Ignition System DiagramFigure 6. Setting Spark Plug Gap IGNITION MODULE CONTINUEDFigure 8. Testing for Spark Warning! Do NOT use a screwdriver to test forspark. Personal injury or damage to equip- ment may result Figure 9. Checking Engine MissTESTING THE SYSTEM CONTINUED Figure 12. Testing Ignition SensorFigure 13. Testing Ignition Coil Figure 14. Testing Ignition Module Note Only one spark should be observed upon initial crankingSection SHUTDOWN FEATURES OIL PRESSURE SWITCHOIL TEMPERATURE SWITCH Figure 3. Testing the Oil Temperature SwitchADDITIONAL SHUTDOWN FEATURES Section SHUTDOWN FEATURESSection OPTIONAL REMOTE PANEL Figure 1. Remote Panel Plug-In ReceptacleFigure 2. Optional Remote Panel Models 004057 and GENERALSection OPTIONAL REMOTE PANEL PagePART TROUBLE SHOOTING 7.2 ENGINE DC CONTROL SYSTEM/ AC TROUBLESHOOTING7.1 GENERATOR & SPEED CONTROL COMPUTER CONTROLLED VARIABLE SPEED RV GENERATORSPage Section GENERATOR & SPEED CONTROL SYSTEM TROUBLESHOOTING REFERENCE CHARTPage Section GENERATOR & SPEED CONTROL SYSTEM PagePROBLEM 1- PRIMING FUNCTION DOES NOT WORK Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGINTRODUCTION PROBLEM 2 - ENGINE WILL NOT CRANK PROBLEM 3 - ENGINE CRANKS BUT WILL NOT STARTSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PagePROBLEM 3 - ENGINE CRANKS BUT WILL NOT START CONTINUED Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PROBLEM 4 - ENGINE STARTS HARD AND RUNS ROUGHPage PROBLEM 5 - ENGINE STARTS THEN SHUTS DOWN AFTER A FEW SECONDS Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGSHUTS DOWN TEST TEST INVERTER Pg FAIL REPLACE INVERTER PagePROBLEM 6 - GENERATOR DOESN’T PULL FULL LOAD PROBLEM 7 - GENERATOR CIRCUIT BREAKER TRIPS / NO AC VOLTAGESection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PagePROBLEM 8 - ENGINE SHUTS DOWN UNDER LOAD PROBLEM 9 - GENERATOR LOSES AC POWER THEN SHUTS DOWNSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PagePROBLEM 10 - NO AC OUTPUT Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING12-WIRE PageSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PROBLEM 10 - NO AC OUTPUT CONTINUEDPage TEST 3- CHECK POWER TO FUEL PUMP TEST 2- CHECK POWER TO PRIMER SWITCHFigure 2. Primer Switch TEST 1- CHECK 7.5 AMP FUSETEST 6- TEST PRIMER SWITCH TEST 7- CHECK WIRE 14A TO FUEL PUMPTEST 8- CHECK POWER SUPPLY TO STARTER MOTOR TEST 4- CHECK BATTERY/BATTERY CIRCUITTEST 9- CHECK WIRE 56 POWER TO STARTER CONTACTOR TEST 10- CHECK A6060 CIRCUIT BOARD POWER SUPPLYFigure 5. Starter Contactor Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGTEST 12- TEST START-STOP SWITCH Figure 7. Start-Stop SwitchTEST 11- TEST STARTER CONTACTOR TEST 13- CHECK FUEL SUPPLYTEST 21 - CHECK A6060 CIRCUIT BOARD OUTPUT TO WIRE TEST 17- CHECK IGNITION POWER SUPPLYFigure 9. Ignition Module & 4-Tab Connector TEST 18- CHECK IGNITION SENSORTEST 23- CHECK CARBURETION TEST 22-TEST AUTOMATIC CHOKETEST 24- CHECK ENGINE Figure 10. Receptacle J2TEST 27- TEST OIL TEMPERATURE SWITCH TEST 26- TEST OIL PRESSURE SWITCHNote Cap the DC Link wires with a wire nut for safety TEST 28 - DC LINK VOLTAGE TESTTEST 30 - 12 POSITION HARNESS SIGNALS TEST TEST 29 - 12 POSITION HARNESS CONTINUITY TESTNote Fluke 87 true RMS meter used in test Figure 10 Free End of 12 Position HarnessSTATOR TESTS TEST 32 - POWER SUPPLY WINDING TEST Figure 11. 12 Position Connector on InverterPin 4 Wire #14 TEST 31 - STATIC TESTS ON INVERTERTEST 36 - AC POWER WINDING TEST AC1/AC2/SL1/SL2 TEST 34 -STATOR RESISTANCE VALUESTEST 35 - BRIDGE RECTIFIER TEST Section ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTINGSection ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING PagePART SPECIFICATIONS AND CHARTS General SpecificationsElectrical Schematic Wiring DiagramPage ENGINE SPEEDS AND VOLTAGE SPECIFICATIONS PartNOMINAL RESISTANCES OF GENERATOR WINDINGS LOAD %Part SPECIFICATIONS & CHARTS ELECTRICAL SCHEMATIC DRAWING NO. 0D4947-B1 OF PageWIRING DIAGRAM DRAWING NO. 0D4947-B Part SPECIFICATIONS & CHARTS2 OF PageGENERAL SPECIFICATIONS MODELGV-220 Part SPECIFICATIONS & CHARTSSPECIFICATIONS & CHARTS CRANKCASE ASSEMBLYCRANKCASE COVER ASSEMBLY Later model small frame GN engines have no crankshaft sleeve bearingCONNECTING ROD ASSEMBLY CRANKSHAFTPISTON Part SPECIFICATIONS & CHARTSPart SPECIFICATIONS & CHARTS PISTON CONTINUEDMODEL CAMSHAFT ASSEMBLY OIL PUMPNOTE 2 Measure pump tip clearance on shaft in crankcase cover Part SPECIFICATIONS & CHARTSSPECIFICATIONS & CHARTS PartMODEL MODELPart SPECIFICATIONS & CHARTS MAJOR FEATURES AND DIMENSIONS GENERATORPage Part SPECIFICATIONS & CHARTS MAJOR FEATURES AND DIMENSIONS INVERTERPage