Generac — “short-to-ground” condition.

A Generac service procedure — check it applies to your exact model before use.

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Procedure

1. 2. Repeat using Stator Lead 44. Test for a short circuit between windings: Connect one test lead to Stator Lead 11. Connect the other test lead to Stator Lead 33. a. The meter should read INFINITY. b. Any reading other that INFINITY indicates a short between windings. Test 9 – Test Brushed Stator Windings General Theory Most brushed stators have three main windings that are needed to produce voltage. The alternator has two main power windings which supply power to the load and a DPE winding to provide excitation voltage to the rotor. These windings must remain isolated from ground or the chassis of the alternator. Procedure Isolate all stator wires from the control panel and voltage regulator. Set DMM to measure resistance. stator. Every connection needs to be checked coming out of the stator for a short to ground. Results If any wire has a direct short-to-ground, or to the chassis of the alternator, replace alternator assembly. flow chart. Test 10 – Check Load Voltage & Frequency Procedure Perform this test the same as Test 1 but apply a load to the generator equal to its rated capacity. Check voltage and frequency with load applied. Frequency should not drop below about 59 Hertz. Voltage should not drop below about 220 VAC nor rise above 265 VAC. Results If voltage and/or frequency drop excessively when If load voltage and frequency are within limits, end tests. Test 11 – Check Load Watts & Amperage Procedure Add up the wattages or amperages of a ll loads powered by the generator at one time. If desired, a clamp-on ammeter may be used to measure current flow. See the Wattage Reference Guide to determine generator limits. appliance for wattage requirements. Section 1 AC Diagnostic Tests Diagnostic Repair Manual 15 Results If unit is overloaded, reduce load. If load is within limits but frequency and voltage still Overloading a generator in excess of its rated wattage capacity can result in damage to the generator and to connected electrical devices. Observe the following to prevent overloading unit: • Add up total wattage of all electrical devices to be connected at one time. This total should NOT be greater than the generator's wattage capacity. • The rated wattage of lights can be taken from light motors can be found on a data label or decal affixed to the device. wattage, multiply volts times ampere rating to determine watts (volts x amps = watts). • Some electric motors, such as induction types, require about three times more watts of power for starting than for running. This surge of power lasts only a few seconds when starting such motors. Be sure to allow for high starting wattage when selecting electrical devices to connect to the generator: Calculate watts needed to start the largest motor. connected loads. Test 12 – Adjust Voltage Regulator wiring diagrams for brush orientation. Procedure Remove cover from end of alternator assembly. Remove two screws holding down the voltage identification. Leave AVR connected to stator and brushes. Set DMM to measure AC voltage. receptacle. Receptacle Verify all material is clear of the alternator before proceeding. Set START-STOP-RUN switch to START. Adjusting screw clockwise will increase voltage, adjusting counterclockwise will lower voltage. Results If there is no change in voltage while adjusting, If voltage is correct, stop testing. Test 13 – Voltage Changeover Switch 120/240 Position The voltage change over switch allows the generator to produce full rated power in the 120 VAC position. The switch must never be switched while the generator is running. Remove all the wiring from the voltage change over switch. Set DMM to read Ohms and zero out the meter. Place the switch in the 120 VAC position and use the switch schematic and number position to perform the following tests. 240 3 2 1 6 5 4 9 8 7 7 9 4 6 1 2 5 8 (COM) 3 3PDT 004977 Section 1 AC Diagnostic Tests 16 Diagnostic Repair Manual Place one test meter lead on contact 2 and the other on contact 3. If CONTINUITY is not measured, rock the switch. If CONTINUITY is still not measured, replace switch. Place one test meter lead on contact 5 and the other on contact 6. If CONTINUITY is not measured, rock the switch. If CONTINUITY is still not measured, replace switch. Place one test meter lead on contact 8 and the other on contact 9. The voltage change over switch allows the generator to produce full rated power in the 240 VAC position. The switch must never be switched while the generator is running. Remove all wiring from the voltage change over switch. Set DMM to read Ohms and zero out the meter. Place the switch in the 240 VAC position and use the switch schematic and number position to perform the following tests. Place one test meter lead on contact 1 and the other on contact 2. If CONTINUITY is not measured, rock the switch. If CONTINUITY is still not measured, replace switch. Place one test meter lead on contact 4 and the other on contact 5. If CONTINUITY is not measured, rock the switch. If CONTINUITY is still not measured, replace switch. Place one test meter lead on contact 7 and the other on contact 8. If CONTINUITY is not measured, rock the switch. If CONTINUITY is still not measured, replace switch. Diagnostic Repair Manual 17 Section 4 EFI Engine Control Diagnostic Tests Basic EFI Theory Electronic Fuel Injection was first introduced to automobiles in the late 1960s. EFI is not new, as its roots were firmly established many years ago. However, EFI is Basic Open-Loop Theory EFI uses a solenoid valve called an injector to meter fuel delivery. The typical system uses 1 injector per cylinder. When the solenoid is energized, fuel sprays out into the intake valve port. Fuel is delivered to the injector by a delivery is controlled by the injector which is cycled by the ECU. The ECU (Engine Control Unit) produces a signal to open the injector for a certain length of time depending on engine conditions transmitted by the sensors. The longer the injector is open, the more fuel is injected. As engine load increases, the injector open time is increased to match the increased airflow. This ECU output signal is called the injector pulse width. The longer the pulse width, the more fuel is injected. In a typical Open-Loop EFI system, there is no oxygen (O2) sensor to monitor or change the fuel delivery. Engine Requirements The correct proportion of fuel is required to be mixed with the incoming air for efficient operation. Most generator engines utilize a ratio of approximately 14.7 parts air to 1 part fuel for the no load to full load power band. This is the chemically correct ratio which results in the lowest average emissions and best power. A rich condition is characterized by an excess of fuel and a lean condition is characterized by an excess of air or lack of fuel. As the load is increased, up to capacity, the throttle is opened and as airflow increases fuel flow must increase to match it. Fuel System pump, regulator, and injector. Fuel is drawn from the tank discharging unused fuel back into the tank. When load demand increases, there is sufficient fuel available. The injector is sealed with an O-ring and has a 2-pin electrical plug to carry switching current to the solenoid windings. When energized, the solenoid core is pulled back, allowing fuel to spray out in a fine, conical pattern. E. Fuel Pump G. Fuel Tank D. Fuel Injector F. Fuel Filter A B C D E F G Section 1 EFI Engine Control Diagnostic Tests 18 Diagnostic Repair Manual Air Metering and Measurement The amount of air entering the engine is controlled by a conventional butterfly valve located in a throttle body assembly. Airflow measurement is by Speed Density. The speed and air temperature to indirectly determine airflow. A relayed to the ECU (Engine Control Unit). Sensor Inputs As with most EFI systems, there are 6 basic inputs that are measured by the ECU; RPM Most systems measure rpm using the ignition coil pulse or crank triggered magnetic/hall effect sensors. Rpm is considered a primary input signal on all EFI systems. Many systems generate an injection pulse for every tachometer pulse, so as rpm is increased, the frequency of injection pulses increases. However, since generator rpm is constant, this input is primarily for governing engine speed. Airflow On many systems, this input is also considered a primary airflow is predetermined and calculated by algorithms in the ECU. On speed density type systems, this input is essential when combined with the rpm signal to calculate airflow. increases which will require more fuel. Throttle Position This input is a secondary input on most systems. It is required mainly for load enrichment when the throttle is rapidly opened. However, a Throttle Position Sensor application. Engine Temperature Engine temperature is a secondary input required mainly to ensure proper starting and warm-up of the engine. When the engine is cold, the air to fuel ratio must be very rich to enable enough fuel to vaporize for proper starting. The computer increases the injector pulse width to supply extra fuel when cold and tapers this fuel off as the cylinder head temperature increases. Once the engine warms past 120 degrees or so, the computer does not need to add any extra fuel. Where a carburetor chokes off air to enrich the mixture when cold, EFI injects extra fuel to achieve the same effect. Air Temperature This is a secondary input required especially on speed density systems. The sensor is usually mounted in the intake manifold or air filter area. As the air temperature drops, its density increases. Denser air requires more fuel. As the temperature of the inducted air increases, the computer reduces the pulse width to compensate for lower density. Basic Operation As explained in Basic Open-Loop Theory, the computer processes all of the voltage signals from the various sensors to determine the engine operating conditions at the moment and delivers the appropriate pulse width to the injector. If engine airflow increases by 10%, the pulse width is also increased by about 10% to keep the air/fuel ratio constant. For example, if the load is doubled from 2000 Watts to 4000 Watts, the number of injections are also doubled to double the fuel flow. The computer looks at the changes in sensor inputs every few milliseconds in order to be ready to modify the pulse width if any of the parameters change. Pin Wire Color Function 1 N/A N/A 2 N/A N/A 3 Black 4 Brown Temperature 5 Green/White CT (Current Txfmr) 6 Grey Idle Switch 7 Red Battery + (POS) 8 Green/White CT (Current Txfmr) 9 Yellow/Green Battery – (GND) 10 Red/White Key Switch 11 Blue/White Crankshaft Sensor 12 Yellow 13 White Injector 14 Green Communication 15 Orange Fuel Pump 16 Red/Black Ignition 16 8 7 1 4 5 6 3 12 15 14 13 9 11 10 2 Section 1 EFI Engine Control Diagnostic Tests Diagnostic Repair Manual 19 EFI Fault Code Diagnostics Fault Indicator Light When the EFI system is connected to a power source (battery) and the generator is not running, the fault light will turn on. Once the generator starts the fault light will turn off. When a failure is detected, the fault light will flash in a series of codes. The severity of the fault will determine the flash code. There are 3 failure levels: • Level 1 will flash and the generator will run. There may be a slight impact on performance. • Level 2 will flash and the generator will shut down if multiple errors are detected. • Level 3 will shut down the generator. flashing 2/10 second on and 2/10 seconds off, this indicates a low or dead battery fault. This sequence stays on and takes precedent before other faults will be displayed. Fault Code Failure Description Fault Flash (seconds) Failure Level 2 TPS (Throttle Position Sensor) Failure On-0.25s, Off-0.5s, On-0.25s 3 3 Cylinder Head Temperature Failure On-0.25s, Off-0.5s Repeat 2X 2 4 Temperature failure On-0.25s, Off-0.5s Repeat 3X 2 5 Low system voltage On-0.25s, Off-0.5s Repeat 4X 3 6 High system voltage On-0.25s, Off-0.5s Repeat 5X 3 7 Cylinder temperature high On-0.25s, Off-0.5s Repeat 6X 1 8 On-0.25s, Off-0.5s Repeat 7X 1 9 On-0.25s, Off-0.5s Repeat 8X 3 11 Fuel injector failure On-1.2s, Off-0.5s, On-0.25s 3 13 Fuel pump failure On-1.2s, Off-0.5s,(On-0.25s, Off-0.5s) Repeat 2X 3 15 Ignition failure On-1.2s, Off-0.5s,(On-0.25s, Off-0.5s) Repeat 4X 3 17 ECU internal failure On-1.2s, Off-0.5s,(On-0.25s, Off-0.5s) Repeat 6X 3 18 Crankshaft Position Sensor Failure On-1.2s, Off-0.5s,(On-0.25s, Off-0.5s) Repeat 7X 1 19 ECU reset On-1.2s, Off-0.5s, (On-0.25s, Off-0.5s) Repeat 8X 3 22 Engine over-speed failure (On-1.2s, Off-0.5s) Repeat 1X, (On-0.25s, Off-0.5s) Repeat 1X 3 24 Load Stability Sensor Failure (On-1.2s, Off-0.5s) Repeat 1X, (On-0.25s, Off-0.5s) Repeat 3X 1 27 Stepper motor binding (On-1.2s, Off-0.5s) Repeat 1X, (On-0.25s, Off-0.5s) Repeat 6X 3 28 Engine starting failure (On-1.2s, Off-0.5s) Repeat 1X, (On-0.25s, Off-0.5s) Repeat 7X 1 None Low Battery On-0.2s, Off-0.2s 0 Battery Charge Coil Open circuit voltage: 23V±5V Load voltage: 14V ±1V
2. 3. 9 PSI (0.02-0.06MPa) Crank Sensor Ohm Reading 270 ±20 Ω (@25°C) Ignition Coil Primary: 1.5Ω ±0.1Ω (@25°C) Secondary: 5.8Ω ±0.6Ω (@25°C) Injection Nozzle Ohm Reading 12Ω Cylinder Head Temp Sensor 10K-3435 Stepper Motor 25Ω ±10%
3. 50. 115kPa

Source: manual:0H2953.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.