The Generac GT-990 is a 0.99 L 2-cylinder air-cooled engine rated at 3600 rpm, producing up to 18.6 kW. It powers generator sets from Generac and Power Systems, including the 12k, GT-530, GTV-760 and Guardian 12 kW. It holds 1.61 L (0.4 gal) of oil.
Also known as: GT-990, Generac GT-990
| Oil capacity | 1.61 L |
|---|---|
| Displacement | 0.992 L |
| Cylinders | 2 |
| Aspiration | Air-cooled |
| Rated speed | 3600 rpm |
| Gross power | 18 kW |
Shared across brands: Generac, Power Systems
This engine also powers 53 machine(s) on Power Equipment Info.
| Symptom | Remedy |
|---|---|
| Generator Produces Zero Voltage or Residual Voltage | TEST 4 - PERFORM FIXED EXCITATION / ROTOR AMP DRAW PERFORM STATOR INSULATION RESISTANCE TEST - SECTION 1.4 PERFORM ROTOR INSULATION RESISTANCE TEST - SECTION 1.4 TEST 7 - TEST STATOR TEST 5 - WIRE CONTINUITY TEST 6 - FIELD BOOST TEST 8 - CHECK ROTOR CIRCUIT REPAIR OR REPLACE FUSES |
| Generator Produces Low Voltage at No-Load | TEST 11 - CHECK AC OUTPUT FREQUENCY TEST 12 - ADJUST ENGINE GOVERNOR TEST 12A - CHECK STEPPER MOTOR CONTROL TEST 2 - CHECK AC OUTPUT VOLTAGE TEST 13- ADJUST VOLTAGE REGULATOR |
| Generator Produces High Voltage at No-Load | REPLACE DEFECTIVE VOLTAGE REGULATOR |
| Voltage and Frequency Drop Excessively When Loads are Applied | TEST 14 - CHECK VOLTAGE AND FREQUENCY UNDER LOAD TEST 79 - CHECK IDLE CONTROL TRANSFORMER TEST 80 - CHECK LC1 & LC2 WIRING TEST 81 - CHECK IDLE CONTROL TRANSFORMER PRIMARY WIRING TEST 15 - CHECK FOR OVERLOAD CONDITION TEST 12 - CHECK AND ADJUST ENGINE GOVERNOR |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.
The Generac GT-990 engine has an oil capacity of 1.61 liters.
The Generac GT-990 has a displacement of 0.992 liters with 2 cylinders.
The Generac GT-990 powers 9 generator set(s), including Generac 12k, Generac GT-530, Generac GTV-760, Generac Guardian 12 kW, Generac Guardian 15 kW.