Kohler COM7.5 Service Manual Download Page 27

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TP-6120 5/02

Section 3 General Troubleshooting

Yes

Correct the problem.

Ignition system problem. Refer

to the Engine Service Manual.

Clean/replace air

cleaner elements.

See Section 2.4.

Engine problem. See the

Engine Service Manual.

Yes

Is fuel supply

turned on?

Check/replenish fuel

supply.

Yes

Turn on fuel supply.

Is gas pressure to system

within specifications?

Have gas provider or

owner correct fuel

pressure problem.

Is there an audible click

indicating fuel solenoid opening

when the unit starts to crank?

Check/repair wiring.

Yes

Go to

Is fuel supply

low?

Yes

Have the fuel supply

installer purge the fuel

lines.

Has the air been purged

from the fuel lines?

Yes

Does unit start?

Yes

Is there a spark?

Did a fault

shutdown

occur?

Yes

Correct the fault and reset the

controller.

Is the air cleaner
dirty or plugged?

Is the fuel hose

pinched?

Summary of Contents for COM7.5

Page 1: ...Commercial Generator Sets Models COM7 5 TP 6120 5 02 Service ...

Page 2: ...ces below immediately after unpacking the products so that the numbers are readily available for future reference Record field installed kit numbers after installing the kits Generator Set Identification Numbers Record the product identification numbers from the generator set nameplate s Model Designation Specification Number Serial Number Accessory Number Accessory Description Engine Identificati...

Page 3: ...and Precleaner 8 2 5 Battery 9 2 6 Ignition System 10 2 6 1 Ignition System Description 10 2 6 2 Spark Plug 10 2 7 Cooling System 10 2 8 Exhaust System 10 2 9 Fuel System 10 2 9 1 Gas Piping 10 2 10 Storage Procedure 11 2 10 1 Engine Oil 11 2 10 2 Fuel 11 2 10 3 Cylinder Lubrication 11 Section 3 General Troubleshooting 13 3 1 Troubleshooting Chart 14 3 2 Generator Set Controller System Troubleshoo...

Page 4: ...own 34 5 2 4 Overspeed Shutdown 34 5 3 Control Board Tests 35 5 3 1 Fuel Control Circuit 35 5 3 2 Speed Sensing and Governor Throttle Control Circuits 35 5 3 3 Start Circuits 35 5 3 4 Ignition Circuits 36 5 4 Control Board Replacement 36 Section 6 Disassembly Reassembly 37 6 1 COM7 5 Disassembly 37 6 1 1 Generator Set Disconnection 37 6 1 2 Alternator Disassembly 37 6 2 COM7 5 Reassembly 39 6 2 1 ...

Page 5: ...nerator set or equipment connected to the set disable the generator set as follows 1 Place the generator set start stop switch in the STOP position 2 Disconnect the power to the battery charger if equipped 3 Remove the battery cables negative lead first Reconnect the negative lead last when reconnecting the battery Follow these precautions to prevent the starting of the generator set by the remote...

Page 6: ...re extinguisher Select a fire extinguisher rated ABC or BC for electrical fires or as recommended by the local fire code or an authorized agency Train all personnel on fire extinguisher operation and fire prevention procedures Exhaust System Carbon monoxide Can cause severe nausea fainting or death The exhaust system must be leakproof and routinely inspected WARNING Generator set operation Carbon ...

Page 7: ...ge equipment or lead to generator set failure Connecting the battery and the battery charger Hazardous voltage can cause severe injury or death Reconnect the battery correctly positive to positive and negative to negative to avoid electrical shock and damage to the battery charger and battery ies Have a qualified electrician install the battery ies Short circuits Hazardous voltage current can caus...

Page 8: ...ardware Use the correct size tools to prevent rounding of the bolt heads and nuts NOTICE When replacing hardware do not substitute with inferior grade hardware Screws and nuts are available in different hardness ratings To indicate hardness American Standard hardware uses a series of markings and metric hardware uses a numeric system Check the markings on the bolt heads and nuts for identification...

Page 9: ...llow the Safety Precautions and Instructions section at the beginning of this manual Keep this manual with the equipment for future reference The equipment service requirements are very important to safe and efficient operation Inspect the parts often and perform required service at the prescribed intervals Maintenance and service must be performed by appropriately skilled and suitably trained mai...

Page 10: ...onal office Africa Europe Middle East London Regional Office Langley Slough England Phone 44 1753 580 771 Fax 44 1753 580 036 Asia Pacific Power Systems Asia Pacific Regional Office Singapore Republic of Singapore Phone 65 264 6422 Fax 65 264 6455 China North China Regional Office Beijing Phone 86 10 6518 7950 86 10 6518 7951 86 10 6518 7952 Fax 86 10 6518 7955 East China Regional Office Shanghai ...

Page 11: ...rpm governing and a local LED for fault annunciation Under very light loads the generator set operates at low speed As loads increase the control system maintains constant generator output voltage by increasing the generator set engine speed The Kohler CH20 engine drives a direct connected variable speed 3 phase voltage specific generator to produce high frequency AC power A 3 phase full wave rect...

Page 12: ... Sleeve Governor Electronic Starter motor Electric Solenoid Shift Lubrication system Full Pressure Oil capacity with filter and cooler L qt 1 9 2 0 Oil type Synthetic 5W 30 Oil filter tightening torque Nm in lb 5 7 9 0 50 80 Oil pressure kPa psi 172 241 25 35 Low oil pressure kPa psi 24 1 13 8 3 5 1 5 Fuel type Natural Gas or Propane Fuel pressure kPa in water column 1 7 to 2 7 7 to 11 Fuel consum...

Page 13: ...air cleaner 5 Spark plugs 2 6 Fuel line 7 Dual fuel block 8 Gas regulator 9 Fuel supply inlet 10 Oil cooler 11 Oil drain valve 12 Oil drain hose 13 Oil filter 14 Alternator 15 Rectifier 16 Rectifier heat sink hidden 17 Shipping bracket 18 Ground connection 19 Oil pan heater 19 1 3 14 4 17 15 7 8 18 16 2 6 5 10 13 11 12 9 Figure 1 4 COM7 5 Service Views ...

Page 14: ...TP 6120 5 02 4 Section 1 Specifications Notes ...

Page 15: ...vicing the equipment Configure the installation to electrically ground the generator setandrelatedequipmentandelectricalcircuitstocomplywith applicable codes and standards Never contact electrical leads or appliances when standing in water or on wet ground because these conditions increase the risk of electrocution Explosive fuel vapors Can cause severe injury or death Use extreme care when handli...

Page 16: ...on clean and dry battery and rack X X Y Battery electrolyte level and specific gravity X Q Electrical System Inspect wiring and components for visible wear or damage X Q Check for abrasions where wiring is subject to motion X X S Check wiring for insulation breakdown X X Y Tighten power and control wiring connections X Y Engine And Mounting Inspect for visible wear or damage X Q Inspect air cleane...

Page 17: ...perature before changing See Figure 2 2 for the oil drain plug filter and fill tube locations 1 Drain the oil a Place an oil collection container below the oil drain and remove the oil drain plug b Allow the engine oil to drain completely c Replace the oil drain plug 2 Replace the oil filter a Place an oil collection container below the oil filter b Remove the oil filter by rotating it countercloc...

Page 18: ...the air cleaner s location Follow the enclosure manufacturer s instructions to open the enclosure and gain access to the air cleaner Wash and oil the precleaner and replace the paper element at the intervals shown in the service schedule Service the air cleaner more often if the generator set operates under dusty or dirty conditions Refer to Maintenance and Service Parts in the Introduction sectio...

Page 19: ...r base Make sure it is secure and not bent or damaged Remove any dirt or debris from the air cleaner base Wipe the base carefully so that no dirt falls into the intake throat c Check the element cover for damage and fit Replace all damaged air cleaner components Check the condition of the rubber seal on the air cleaner stud and replace the seal if it is worn or damaged d Install the paper element ...

Page 20: ... Note Do not block the generator set cooling air inlet 2 8 Exhaust System Remove all combustible materials from the exhaust location Combustible materials include building materials as well as natural surroundings Keep dry field grass foliage and combustible landscaping material a safe distance from the exhaust outlet Periodically inspect the exhaust system components exhaust manifold exhaust line...

Page 21: ...ngine crankcase 4 Refill the engine crankcase with an oil having a viscosity appropriate for the particular climate 5 Run the generator set for a few minutes to distribute the clean oil 6 Stop the generator set 2 10 2 Fuel 1 With the generator set running shut off the gas supply 2 Run the generator set until the engine stops from lack of fuel 2 10 3 Cylinder Lubrication 1 Remove the spark plugs 2 ...

Page 22: ...TP 6120 5 02 12 Section 2 Scheduled Maintenance Notes ...

Page 23: ...cting the battery WARNING Disabling the generator set Accidental starting can cause severe injury or death Before working on the generator set or equipment connected to the set disable the generatorsetasfollows 1 Placethegeneratorsetstart stop switch in the STOP position 2 Disconnect the power to the battery charger if equipped 3 Remove the battery cables negative lead first Reconnect the negative...

Page 24: ...Reset the controller Section 5 1 6 Controller board problem Test the board as described in Section 5 3 Connect a spare control board to verify that the board needs to be replaced Sections 5 3 and 5 4 Unit cranks but does t t t Air cleaner clogged Clean or replace the air cleaner Section 2 4 not start Fuel problem Check the fuel supply and replenish if necessary Verify that the fuel valve is open C...

Page 25: ...ection 2 7 Engine overload Reduce the load on the generator set Faulty spark plug Replace or regap the spark plugs Section 2 6 2 Fuel supply problem Check the valves and fuel pressure Section 4 5 Governor system problem Check the governor and throttle linkage Section 4 2 Unit does not supply load Fuel supply problem Check for the correct fuel and fuel block connection Section 4 5 Excessive load Ch...

Page 26: ... to RUN position Does engine start and run normally No Yes Unit is okay Go to B Check starter wiring relay and motor Check voltage to starter relay on lead 71 See Section 4 3 Is the starter okay Replace controller board Yes No Does unit stop while master switch is still in AUTO No Yes Generator set is okay The system may have been sent a remote stop command or there may be a problem with the syste...

Page 27: ...system within specifications Have gas provider or owner correct fuel pressure problem No Is there an audible click indicating fuel solenoid opening when the unit starts to crank Check repair wiring No Yes Yes No No Go to B Is fuel supply low No Yes No Have the fuel supply installer purge the fuel lines Has the air been purged from the fuel lines No No Yes Does unit start Yes Is there a spark No Di...

Page 28: ...rate erratically No Does unit stop while master switch is in AUTO and system controller is disconnected Go to E B Yes Go to C Yes Unit is okay No Yes Does unit stop after running normally No Disconnect and reconnect the harness to verify a good connection Repair replace harness ...

Page 29: ...air cleaner plugged Possible generator set overload Does reducing load solve problem Open circuit breaker to reduce load Clean or replace air cleaner elements Yes Reduce the load to keep it within the rated range Lacks Power or Runs Erratically No Yes No Are spark plugs okay See Section 2 6 2 Regap or replace Yes Go to D C Is fuel pressure 7 11 in water Yes Have fuel supply installer correct fuel ...

Page 30: ...using an oxygen sensor See Section 4 5 Is the fuel adjustment correct Adjustingthefuelsystemmayvoidtheemissionscertification Onlytrainedandauthorizedservicetechniciansshouldadjust the fuel system See Section 4 5 4 Check the throttle linkage See Section 4 2 Throttle linkage binding Check carburetor See the Engine Service Manual for carburetor service information Repair replace ignition components a...

Page 31: ...Are spark plug and wires okay Replace or regap spark plugs See Section 2 6 2 E Adjust the fuel metering valve Possible intermittent wiring problem or control board malfunction Check all wiring and components Yes No Yes Adjustingthefuelsystemmayvoidtheemissionscertification Onlytrainedandauthorizedservicetechniciansshouldadjustthefuelsystem See Section 4 5 4 Start the unit Does it stop after normal...

Page 32: ...TP 6120 5 02 22 Section 3 General Troubleshooting Notes ...

Page 33: ...al enclosures are in place Moving rotor WARNING Fire Can cause severe injury or death Do not smoke or permit flames or sparks near fuels or the fuel system WARNING Servicing the air cleaner A sudden backfire can cause severe injury or death Do not operate the generator set with the air cleaner removed 4 1 Voltage Rectifier The voltage rectifier converts AC voltage from the alternator into DC volta...

Page 34: ...ormally require adjustment If the engine operates erratically check the following connections and conditions before adjusting the governor D Check the electrical connections and wire harnesses for clean tight connections D Check the speed sensing connections at rectifier AC terminals 2 and 3 Poor connections may cause an erratic signal which could cause the unit to shut down D Check the electrical...

Page 35: ... Throttle linkage 2 TP5867 Figure 4 3 Governor 4 2 2 Stepper Motor Check Use the following procedure to test the operation of the governor stepper motor Stepper Motor Test Procedure 1 Stop the generator set and disconnect the battery 2 Manually move the governor linkage fully counterclockwise open throttle See Figure 4 3 3 Reconnect the battery The stepper motor should move clockwise to the closed...

Page 36: ... relay check for 12 VDC to the starter motor during the crank attempt If there is voltage to the relay but not to the starter motor check the connection between the relay and the starter motor If the connection is good replace the relay If there is voltage to the starter motor but the starter motor does not crank the engine refer to the Kohler CH20 Engine Service Manual for starter service informa...

Page 37: ... pressure regulator 3 Fuel inlet 4 Fuel lock off Do not adjust 5 Fuel metering valves 6 Inlet pressure check location plug tp6120 2 1 3 6 4 Figure 4 6 Secondary Regulator with fuel block 4 5 2 Fuel Solenoid Valve The fuel solenoid valve is a 12 VDC valve energized by lead 70 when the generator set controller is in the crank or the run mode The fuel solenoid valve is supplied by the enclosure manuf...

Page 38: ...emissions requirements and sealed to discourage field adjustments If the fuel system requires recalibration only trained authorized service technicians may adjust the fuel metering valves Always use an oxygen sensor available from Kohler Co when adjusting the fuel metering valves See Maintenance and Service Parts in this manual for the sensor part number Note Changing the fuel system adjustments m...

Page 39: ...4 Set the ohmmeter on the R x 1 scale Touch the ohmmeter leads together and adjust the ohmmeter to show zero ohms 5 Check the cold resistance of the stator windings by connecting the meter leads to stator leads 1 and 2 1 and 3 and 2 and 3 See Figure 4 11 for stator winding resistance values Replace the stator if any of the resistance checks reveal an open winding Note Most ohmmeters do not measure...

Page 40: ...circuit Any other reading indicates a short replace the HOT switch photos7 1 1 High oil temperature switch 1 Figure 4 12 High Oil Temperature HOT Switch Low Oil Pressure LOP Switch The normally closed LOP switch opens when the engine oil pressure reaches the normal operating level and closes if the oil pressure drops below a preset minimum Use an ohmmeter to check the continuity between pin P1 17 ...

Page 41: ...on 5 1 3 for remote start stop connection information 5 1 1 Starting the Generator Set The following procedures describe the actions required to start the generator set Reset the controller by moving the generator set master switch to the STOP position after applying battery voltage for the first time or after a voltage interruption Local Starting Move the generator set master switch to the RUN po...

Page 42: ...bbreviations used in the wiring diagram 5 1 5 Resetting the Controller Move the generator set master switch to the STOP position and then release it to reset the controller Reset the controller after applying power for the first time or to clear a fault condition See Section 5 1 6 for more information about faults Note If the power to the controller has been disconnected and reconnected the contro...

Page 43: ...tdowns 5 2 Fault Shutdown Tests Verify operation of the controller overspeed overcrank low coolant level low oil pressure and high engine temperature shutdowns by performing the following tests with the generator set running Observe the LED on the controller circuit board during the tests Refer to the service views in Section 1 4 for component locations Follow the enclosure manufacturer s instruct...

Page 44: ...D lights after approximately 75 seconds of cyclic cranking three attempts to start The manufacturer sets the circuit board for three cranking attempts crank 15 seconds rest 15 seconds crank 15 seconds rest 15 seconds crank 15 seconds shutdown Use the following procedure to test the overcrank shutdown operation Overcrank Shutdown Test Procedure 1 Turn off the fuel supply to prevent flooding 2 Move ...

Page 45: ... set is running Replace guards screens and covers before operating the generator set Short circuits Hazardous voltage current can cause severe injury or death Short circuits can cause bodily injury and or equipment damage Do not contact electrical connections with tools or jewelry while making adjustments or repairs Remove all jewelry before servicing the equipment 5 3 1 Fuel Control Circuit Move ...

Page 46: ...trol Board Replacement Procedure 1 Move the system controller switch to the STOP or OFF position 2 Move the generator set master switch to the STOP position The switch will return to the center position when released 3 Disconnect power to the battery charger if equipped 4 Disconnect the generator set engine starting battery negative lead first 5 Disconnect the three 3 wiring harness connectors fro...

Page 47: ... Disconnect the battery charger if equipped 5 Disconnect the battery negative lead first 6 Disconnect the three alternator AC leads from the rectifier 7 Remove ducting from around the generator set assembly as instructed by the enclosure manufacturer 6 1 2 Alternator Disassembly Perform the following steps to disassemble the alternator for maintenance 1 Remove four screws from the bearing cover Se...

Page 48: ... the stator laminations See Figure 6 4 7 Loosen the thrubolt See Figure 6 5 8 Loosen the rotor fan assembly by lightly tapping on alternate sides with a rubber mallet Use only a rubber mallet to prevent damage to the bolt 9 Remove the thrubolt and rotor 1 2 3 4 1 1 End bracket 2 Two 1 4 20 in holes four inches apart for use with slide hammer or puller 3 Slide hammer 4 Adapter with long bolts attac...

Page 49: ...See Figure 6 8 8 9 7 2 3 4 5 6 1 Thrubolt 2 Ball bearing 3 Stator 4 Rotor and fan assembly 5 Air inlet guard 6 Alternator adapter casting 7 End bracket casting 8 Intake duct 9 Bearing cover 1 Figure 6 6 Alternator exploded view 4 Place guide pins or headless bolts in the stator mounting screw holes as a guide for reinstalling the stator Stator damage can occur if it is not installed correctly Note...

Page 50: ... the end bracket casting against the mating casting before installing the bolts 9 Clean and install the end bracket bolts Tighten the bolts to 38 0 Nm 28 ft lbs using the A B C D tightening sequence shown in Figure 6 10 10 Replace the bearing cover and install the screws 6 2 2 Generator Set Connection 1 Check that the remote start stop switch is in the STOP position 2 Reconnect the three alternato...

Page 51: ...TP 6120 5 02 41 Section 7 Wiring Diagrams Section 7 Wiring Diagrams Diagram or Drawing Drawing Number Reference Schematic Diagrams Wiring Diagram GM20551 Figure 7 1 Schematic ADV 6654 Figure 7 2 ...

Page 52: ...TP 6120 5 02 42 Section 7 Wiring Diagrams Figure 7 1 Wiring Diagram GM20551 ...

Page 53: ...TP 6120 5 02 43 Section 7 Wiring Diagrams Figure 7 2 Schematic ADV 6654 ...

Page 54: ...TP 6120 5 02 44 Section 7 Wiring Diagrams Notes ...

Page 55: ...rmer Cu copper cu in cubic inch cw clockwise CWC city water cooled cyl cylinder D A digital to analog DAC digital to analog converter dB decibel dBA decibel A weighted DC direct current DCR direct current resistance deg degree dept department dia diameter DI EO dual inlet end outlet DIN Deutsches Institut fur Normung e V also Deutsche Industrie Normenausschuss DIP dual inline package DPDT double p...

Page 56: ...on optional OS oversize overspeed OSHA Occupational Safety and Health Administration OV overvoltage oz ounce p pp page pages PC personal computer PCB printed circuit board pF picofarad PF power factor ph Æ phase PHC Phillips head crimptite screw PHH Phillips hex head screw PHM pan head machine screw PLC programmable logic control PMG permanent magnet generator pot potentiometer potential ppm parts...

Page 57: ...op of nut 3 Below top of nut Figure 1 Acceptable Bolt Lengths Steps for common hardware application 1 Determine entry hole type round or slotted 2 Determine exit hole type fixed female thread weld nut round or slotted For round and slotted exit holes determine if hardware is greater than 1 2 inch in diameter or 1 2 inch in diameter or less Hardware that is greater than 1 2 inch in diameter takes a...

Page 58: ... 0 32 68 0 50 95 0 70 1 2 13 Nm ft lb 60 0 44 92 0 68 130 0 96 1 2 20 Nm ft lb 66 0 49 103 0 76 146 0 108 9 16 12 Nm ft lb 81 0 60 133 0 98 187 0 138 9 16 18 Nm ft lb 91 0 67 148 0 109 209 0 154 5 8 11 Nm ft lb 113 0 83 183 0 135 259 0 191 5 8 18 Nm ft lb 128 0 94 208 0 153 293 0 216 3 4 10 Nm ft lb 199 0 147 325 0 240 458 0 338 3 4 16 Nm ft lb 222 0 164 363 0 268 513 0 378 1 8 Nm ft lb 259 0 191 ...

Page 59: ...nal External Tooth Lock Hardness Grades American Standard Grade 2 Grade 5 Grade 8 Grade 8 9 Hex Socket Head Metric Number stamped on hardware 5 8 shown 5 8 Allent head screw is a trademark of Holo Krome Co Phillipsr screw is a registered trademark of Phillips Screw Company Sample Dimensions 1 4 20 x 1 Major Thread Diameter In Fractional Inches Or Screw Number Size Length In Inches Screws and Bolts...

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Page 64: ... Wisconsin 53044 Phone 920 565 3381 Fax 920 459 1646 For the nearest sales service outlet in the US and Canada phone 1 800 544 2444 KohlerPowerSystems com Kohler Power Systems Asia Pacific Headquarters 7 Jurong Pier Road Singapore 619159 Phone 65 264 6422 Fax 65 264 6455 ...

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