Generac Power Systems 75, 55, 65 manual Test 36 Check Carburetion, Test 37 Check Choke Solenoid

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Section 7

DIAGNOSTIC TESTS

Figure 7-42 – Tightening the Jam Nut

INSTALL ROCKER ARM COVER

1.Use a new rocker arm cover gasket. Install the rocker arm cover and retain with four screws.

RESULTS:

Adjust valves to specification and retest. If problem continues, go to Test 38.

TEST 36 - CHECK CARBURETION

DISCUSSION:

If the engine cranks but will not start, one possible cause of the problem might be the carburetion system.

PROCEDURE:

Before making a carburetion check, be sure the fuel sup- ply tank has an ample supply of fresh, clean gasoline. Check that all shutoff valves are open and fuel flows freely through the fuel line.

Make sure the automatic choke operates properly.

If the engine will not start, remove and inspect the spark plug. If the spark plug is wet, look for the following:

❏Overchoking.

❏Excessively rich fuel mixture.

❏Water in fuel.

❏Intake valve stuck open.

❏Needle/float stuck open.

If the spark plug is dry look for the following:

❏Leaking carburetor mounting gaskets.

❏Intake valve stuck closed.

❏Inoperative fuel pump.

❏Plugged fuel filter(s).

❏Varnished carburetor

If the engine starts hard or will not start, look for the following:

❏Physical damage to the AC generator. Check the Rotor for contact with the Stator.

❏Starting under load. Make sure all loads are discon- nected or turned off before attempting to crank and start the engine.

❏Check that the automatic choke is working properly.

RESULTS:

If problem has not been solved, go to Test 37. If car- buretor is varnished, clean or replace.

1.Remove fuel line at carburetor and ensure that there is an ade- quate amount of fuel entering the carburetor.

2.Remove the float bowl and check to see if there is any foreign matter in bottom of carburetor bowl.

3.The float is plastic and can be removed for access to the nee- dle so it can be cleaned.

4.With all of this removed carburetor cleaner can be used to clean the rest of the carburetor before reassembly.

5.After cleaning carburetor with an approved carburetor cleaner, blow dry with compressed air and reassemble.

Shelf life on gasoline is 30 days. Proper procedures need to be taken for carburetors so that the fuel doesn’t varnish over time. A fuel stabilizer must be used at all times in order to ensure that the fuel is fresh at all times.

TEST 37 - CHECK CHOKE SOLENOID

DISCUSSION:

The automatic choke is active only during cranking. When the Start-Stop Switch is held at “START”, a crank relay on the Engine Controller circuit board is energized closed to (a) crank the engine and (b) deliver a cyclic voltage to the Choke Solenoid via Wire 90. The Choke Solenoid will be pulled in for about two seconds, then deactivate for about two seconds. This cyclic choking action will continue as long as the engine is being cranked.

PROCEDURE:

1.Operational Check: Crank the engine. While cranking, the choke solenoid should pull in about every 2 seconds (2 sec- onds ON, 2 seconds OFF). If the choke solenoid does not pull in, try adjusting the choke as follows.

2.Pre-Choke Adjustment: With the CHOKE SOLENOID not actu- ated, the carburetor CHOKE PLATE should be approximately 1/8 Inch from its full open position. Verify choke is completely open once engine is warmed up. If not, power will be down and emissions will be up. Adjust position of BI-METAL HEATER ASSEMBLY by loosening screws until unit starts when cold and the choke closes when engine is up to temperature. Tighten the screws to complete the adjustment.

3.Choke Solenoid Adjustment: Loosen the screws that retain the CHOKE SOLENOID to its bracket. Slide the CHOKE SOLE- NOID in the slotted holes of the bracket to adjust axial move-

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Contents Diagnostic Repair Manual Safety Replacement PartsTable of Contents Section Specifications & Charts Section Exploded Views / Part NumbersElectromagnetic Fields MagnetismElectromagnetic Induction Simple AC Generator More Sophisticated AC GeneratorGenerator Operating Diagram Generator AC Connection System Field BoostLine Breakers 120 Volts only Connection for 120 Volts Only Reconnection for Dual Voltage OutputRotor Assembly Stator AssemblyBattery Charge Components Brush HolderExcitation Circuit Components GeneralAdjustment Procedure Crankcase BreatherVoltage Regulator DescriptionInstall Breather Install oil vapor collector and retainerControl Panel Component Identification Check BreatherCleaning the Generator Effects of Dirt and MoistureInsulation Resistance Testers Drying the GeneratorBrushing and Vacuum Cleaning Stator Insulation ResistanceCloth or Compressed AIR Stator SHORT-TO-GROUND TestsTesting Rotor Insulation Testing Stator InsulationTesting Rotor Insulation MegohmmeterMeters VOMMeasuring AC Voltage Measuring DC VoltageMeasuring Current Measuring AC FrequencyMeasuring Resistance Electrical Units Ohms LAWAmpere VoltOperational Analysis IntroductionCircuit CONDITION- Rest Circuit CONDITION- Priming Circuit CONDITION- Cranking Circuit CONDITION-RUNNING Choke Heater CHCircuit CONDITION- Shutdown Circuit CONDITION- Fault Shutdown Sure Switch LOPBattery Recommended BatteryBattery Cables Engine Controller Circuit BoardSTART-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 Procedure Test 1- Check NO-LOAD Voltage FrequencyTest 2- Check Engine Governor DiscussionGovernor Adjustment Test 3- Test Excitation Circuit BreakerTest 4- Fixed Excitation TEST/ROTOR AMP Draw If continuity was indicated, go to TestTest 5- Wire Continuity Re-connect Wire 11 and Wire 22 to the Voltage RegulatorSet the VOM to measure AC voltage Set a VOM to its Rx1 scaleTest 7 Test Stator DPE Winding Test 6- Check Field BoostIf field boost checks good, replace the Voltage Regulator Test 8- Check Sensing Leads / Power Windings Across Wires Ohms11S 22S Model OhmsTest 9- Check Brush Leads Test 10 Check Brushes & Slip RingsTest 11- Check Rotor Assembly Tance Tests ProcedureTest 12 Check Main Circuit Breaker Replace the Rotor if it fails the testTest 15 Check Battery Charge Output Test 16 Check Battery Charge RectifierBattery Charge Rectifier BCR is a full wave rectifier Test 13- Check Load Voltage Frequency10. Battery Charge Rectifier Short to GroundTest 19- Test Primer Switch Set a VOM to read battery voltage 12 VDCAlso see Fuel Primer Switch, Test 18 TRY Cranking the EngineTest 20- Check Fuel Pump 13. The LPG Fuel Solenoid FSTest 23- Check Power Supply to Circuit Board Test 22- Check Battery & CablesTest 21- Check 7.5 AMP Fuse Test 24 Check START-STOP Switch 17. Start-Stop SwitchTest 26- Check Starter Contactor Relay Set a VOM to measure DC voltage 12 VDCTest 27 Check Starter Motor Test 26A Check Starter ContactorConditions Affecting Starter Motor Performance Checking the Pinion Tools for Starter Performance TestMeasuring Current TachometerTesting Starter Motor Test 28- Check Fuel SupplyTest Bracket Remove Starter Motor28 LP Gas Carburetion Diagram Discussion LPG ModelsTest 29 Check Wire 14 Power Supply Test 30 Check WireBattery voltage is not measured, proceed to Step Crank the engine. The meter should indicate battery voltageTest 31 Check Fuel Solenoid Gasoline Models Test 32 Check Ignition SparkCylinder Balance Test Conclusion No cylinder is weakest of the two cylindersTest 34 Check and Adjust Ignition Magnetos Test 33 Check Spark Plugs37. Setting Ignition Magneto Armature Air Gap Test 35 Check Valve Adjustment Adjusting Valve ClearanceChecking Flywheel Magnet Flywheel KEYTest 36 Check Carburetion Install Rocker ARM CoverTest 37 Check Choke Solenoid 43. Connector Adjust the regulated pressure on the gauge to 80 psi Down Test / Compression TestRepeat Steps 1 through 8 on remaining cylinder Check CompressionTest 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 Major Disassembly ENCLOSURE/PANEL RemovalStator Removal Rotor 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 QTY Description Flywheel Assy GT-990Control Panel Drawing No E1013-A Wire ASM GRD STD Conn Switch Spdt ON-MOM-ONSwitch 6A Spdt Not Shown PANEL, TOP ControlTwin Engine Drawing No E1014-B ASSEMBLY, Crankcase RV ASSEMBLY, BreatherASSEMBLY, Head #1 ASSEMBLY, OIL Fill CAPLP Regulator Drawing No E1530 CASTING, Twin Regulator Housing Washer Flat M4SOLENOID, Twin Regulator SPRING-SOLENOID PlungerSpecifications & Charts Generator Specifications Nominal Resistances of Generator Windings AT 68FEngine Speeds and Voltage Specifications Page Electrical Data Electrical Data PO BOX 297 WHITEWATER, WI

65, 75, 55 specifications

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