Generac Power Systems 75, 55 Checking the Pinion, Tools for Starter Performance Test, Tachometer

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Section 7

DIAGNOSTIC TESTS

PROCEDURE:

The battery should have been checked prior to this test and should be fully charged.

Set a VOM to measure DC voltage (12 VDC). Connect the meter positive (+) test lead to the Starter Contactor stud which has the small jumper wire con- nected to the Starter. Connect the common (-) test lead to the Starter Motor frame.

Set the Start-Stop Switch to its "START" position and observe the meter. Meter should Indicate battery volt- age, Starter Motor should operate and engine should crank.

RESULTS:

1.If battery voltage is indicated on the meter but Starter Motor did not operate, remove and bench test the Starter Motor (see fol- lowing test).

2.If battery voltage was indicated and the Starter Motor tried to engage (pinion engaged), but engine did not crank, check for mechanical binding of the engine or rotor.

If engine turns over slightly, go to Test 35 “Check and Adjust Valves.”

NOTE: If a starting problem is encountered, the engine itself should be thoroughly checked to eliminate it as the cause of starting difficulty. It is a good practice to check the engine for freedom of rotation by removing the spark plugs and turn- ing the crankshaft over slowly by hand, to be sure it rotates freely.

WARNING!: DO NOT ROTATE ENGINE WITH ELECTRIC STARTER WITH SPARK PLUGS REMOVED. ARCING AT THE SPARK PLUG ENDS MAY IGNITE THE GASOLINE VAPOR EXITING THE SPARK PLUG HOLE.

Figure 7-21. – Starter Motor (SM)

CHECKING THE PINION:

When the Starter Motor is activated, the pinion gear should move and engage the flywheel ring gear. If the pinion does not move normally, inspect the pinion for binding or sticking.

Figure 7-22. – Check Pinion Gear Operation

TOOLS FOR STARTER PERFORMANCE TEST:

The following equipment may be used to complete a performance test of the Starter Motor:

❏A clamp-on ammeter.

❏A tachometer capable of reading up to 10,000 rpm.

❏A fully charged 12-volt battery.

MEASURING CURRENT:

To read the current flow, in AMPERES, a clamp-on ammeter may be used. This type of meter indicates current flow through a conductor by measuring the strength of the magnetic field around that conductor.

Figure 7-23. – Clamp-On Ammeter

TACHOMETER:

A tachometer is available from your Generac Power Systems source of supply. Order as P/N 042223. The tachometer measures from 800 to 50,000 RPM (see Figure 7-24).

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Contents Diagnostic Repair Manual Replacement Parts SafetyTable of Contents Section Exploded Views / Part Numbers Section Specifications & ChartsElectromagnetic Fields MagnetismElectromagnetic Induction More Sophisticated AC Generator Simple AC GeneratorGenerator Operating Diagram Generator AC Connection System Field BoostLine Breakers 120 Volts only Reconnection for Dual Voltage Output Connection for 120 Volts OnlyStator Assembly Rotor AssemblyGeneral Battery Charge ComponentsBrush Holder Excitation Circuit ComponentsDescription Adjustment ProcedureCrankcase Breather Voltage RegulatorCheck Breather Install BreatherInstall oil vapor collector and retainer Control Panel Component IdentificationDrying the Generator Cleaning the GeneratorEffects of Dirt and Moisture Insulation Resistance TestersStator SHORT-TO-GROUND Tests Brushing and Vacuum CleaningStator Insulation Resistance Cloth or Compressed AIRMegohmmeter Testing Rotor InsulationTesting Stator Insulation Testing Rotor InsulationMeasuring DC Voltage MetersVOM Measuring AC VoltageMeasuring Current Measuring AC FrequencyMeasuring Resistance Volt Electrical UnitsOhms LAW AmpereOperational Analysis IntroductionCircuit CONDITION- Rest Circuit CONDITION- Priming Circuit CONDITION- Cranking Choke Heater CH Circuit CONDITION-RUNNINGCircuit CONDITION- Shutdown Sure Switch LOP Circuit CONDITION- Fault ShutdownEngine Controller Circuit Board BatteryRecommended Battery Battery CablesSTART-STOP Switch Fuel Primer SwitchAMP Fuse Starter Contactor Relay Starter Motor Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Troubleshooting Flowcharts Discussion ProcedureTest 1- Check NO-LOAD Voltage Frequency Test 2- Check Engine GovernorIf continuity was indicated, go to Test Governor AdjustmentTest 3- Test Excitation Circuit Breaker Test 4- Fixed Excitation TEST/ROTOR AMP DrawSet a VOM to its Rx1 scale Test 5- Wire ContinuityRe-connect Wire 11 and Wire 22 to the Voltage Regulator Set the VOM to measure AC voltageTest 7 Test Stator DPE Winding Test 6- Check Field BoostIf field boost checks good, replace the Voltage Regulator Model Ohms Test 8- Check Sensing Leads / Power WindingsAcross Wires Ohms 11S 22STest 10 Check Brushes & Slip Rings Test 9- Check Brush LeadsReplace the Rotor if it fails the test Test 11- Check Rotor AssemblyTance Tests Procedure Test 12 Check Main Circuit BreakerTest 13- Check Load Voltage Frequency Test 15 Check Battery Charge OutputTest 16 Check Battery Charge Rectifier Battery Charge Rectifier BCR is a full wave rectifierShort to Ground 10. Battery Charge RectifierTest 18 TRY Cranking the Engine Test 19- Test Primer SwitchSet a VOM to read battery voltage 12 VDC Also see Fuel Primer Switch,13. The LPG Fuel Solenoid FS Test 20- Check Fuel PumpTest 23- Check Power Supply to Circuit Board Test 22- Check Battery & CablesTest 21- Check 7.5 AMP Fuse 17. Start-Stop Switch Test 24 Check START-STOP SwitchSet a VOM to measure DC voltage 12 VDC Test 26- Check Starter Contactor RelayTest 27 Check Starter Motor Test 26A Check Starter ContactorConditions Affecting Starter Motor Performance Tachometer Checking the PinionTools for Starter Performance Test Measuring CurrentRemove Starter Motor Testing Starter MotorTest 28- Check Fuel Supply Test BracketDiscussion LPG Models 28 LP Gas Carburetion DiagramCrank the engine. The meter should indicate battery voltage Test 29 Check Wire 14 Power SupplyTest 30 Check Wire Battery voltage is not measured, proceed to StepTest 32 Check Ignition Spark Test 31 Check Fuel Solenoid Gasoline ModelsConclusion No cylinder is weakest of the two cylinders Cylinder Balance TestTest 33 Check Spark Plugs Test 34 Check and Adjust Ignition Magnetos37. Setting Ignition Magneto Armature Air Gap Flywheel KEY Test 35 Check Valve AdjustmentAdjusting Valve Clearance Checking Flywheel MagnetTest 36 Check Carburetion Install Rocker ARM CoverTest 37 Check Choke Solenoid 43. Connector Check Compression Adjust the regulated pressure on the gauge to 80 psiDown Test / Compression Test Repeat Steps 1 through 8 on remaining cylinderTest 40 Test OIL Temperature Switch Test 39 Check OIL Pressure SwitchIf all steps check GOOD, go to Test Test 42 Check LPG Fuel Solenoid Test 41 Test Choke HeaterShort to Ground 49. Fuel Solenoid Rotor Removal Major DisassemblyENCLOSURE/PANEL Removal Stator RemovalEngine Removal Belt TensioningStarter Removal FLYWHEEL/MAGNETO Removal Page Section Exploded Views / Part Numbers Part NO. QTY Description Enclosure Drawing No E1011-B QTY Description Sheet Metal Drawing No E1012-E Flywheel Assy GT-990 QTY DescriptionControl Panel Drawing No E1013-A PANEL, TOP Control Wire ASM GRD STD ConnSwitch Spdt ON-MOM-ON Switch 6A Spdt Not ShownTwin Engine Drawing No E1014-B ASSEMBLY, OIL Fill CAP ASSEMBLY, Crankcase RVASSEMBLY, Breather ASSEMBLY, Head #1LP Regulator Drawing No E1530 SPRING-SOLENOID Plunger CASTING, Twin Regulator HousingWasher Flat M4 SOLENOID, Twin RegulatorSpecifications & Charts Nominal Resistances of Generator Windings AT 68F Generator SpecificationsEngine Speeds and Voltage Specifications Page Electrical Data Electrical Data PO BOX 297 WHITEWATER, WI

65, 75, 55 specifications

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