Specifications
| Frequency | 60.0 Hz |
|---|---|
| Standby power | 20 kW |
| Standby kVA | 25 |
| Prime power | 18 kW |
| Controller | Mobile Digital |
| Alternator | G350 (6-pole, Class H insulation) |
| Voltage options | 120/240 V, 240 V |
| Phase | 3-phase |
| Rated current | 50 A |
| Power factor | 0.8 |
| Dimensions (L×W×H) | 2134×1016×1524 mm |
| Dry weight | 987 kg |
| Fuel tank | 105.0 L |
| Tank runtime | 24.375 hr |
Maintenance & consumables
for the John Deere E3805| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | — | 250 hr | |||
| Fuel filter | — | 250 hr | |||
| Oil filter | — | 500 hr | |||
| Battery | — | 250 hr | |||
| Belt | — | 500 hr | |||
| Coolant | 4.7 L | — | 2000 hr | ||
| Oil | 4.7 L | — | 50 hr | ||
| Spark plug | — | 50 hr |
Common questions
What size generator is the Generac MMG25FHI?
The Generac MMG25FHI is rated 20 kW standby (25.0 kVA).
What engine is in the Generac MMG25FHI?
The Generac MMG25FHI is powered by the John Deere E3805 engine.
What is the continuous rating of the Generac MMG25FHI?
The Generac MMG25FHI is rated 18 kW prime (23 kVA), against 20 kW standby.
How much does the Generac MMG25FHI weigh?
The Generac MMG25FHI has a dry weight of 987 kg (2177 lb).
What size fuel tank does the Generac MMG25FHI have?
The Generac MMG25FHI has a 105 liter (28 US gallon) fuel tank, giving about 24.375 hours of runtime.
What voltage does the Generac MMG25FHI produce?
The Generac MMG25FHI is offered in 120/240 V, 240 V, 3-phase-phase.
Which alternator is fitted to the Generac MMG25FHI?
The Generac MMG25FHI uses a G350 alternator. It has 6 poles. Insulation class H.
Troubleshooting
15Symptoms & remedies
| Symptom | Cause | Remedy |
|---|---|---|
| Low Fuel Level Shutdown | Low fuel level | Check fuel level in LCD window of controller. |
| Low Fuel Level Shutdown | Unit not level | Confirm that unit is sitting level to ensure an accurate reading. |
| Low Fuel Level Shutdown | Fuel tank leaking | Check tank for leaks. |
| Low Fuel Level Shutdown | Damaged fuel sender or wiring | Check for continuity between sender and engine controller. (See Wiring Diagrams and Service Log.) |
| Low Oil Pressure Shutdown | Low oil level | Check oil level on dipstick. Add oil, if needed. |
| Low Oil Pressure Shutdown | Oil leaking from engine | Visually inspect the engine for leaks. Restart unit and verify loss of pressure. Shut down immediately if pressure does not reach 5 psi (34 kPa) within five seconds. |
| Low Oil Pressure Shutdown | Oil pressure sender | See engine operator's manual to identify corrective action. |
| Low Coolant Level Shutdown | Low coolant level | Allow engine to cool, then check coolant level in radiator. Add coolant, if needed. |
| Low Coolant Level Shutdown | Coolant hoses leaking | Inspect hoses for leaks. Repair or replace as necessary. |
| Low Coolant Level Shutdown | Engine block or water pump leaking | Visually inspect for leaks. Verify no coolant has mixed with the engine oil (oil will appear milky). See engine operator's manual for additional information. |
| High Coolant Temperature Shutdown | Low coolant level | Add coolant if needed. Allow engine to cool, then check coolant level in radiator. Restart engine and check coolant temperature (on controller). Stop engine immediately if coolant temperature is 210°F (99°C) or more. |
| High Coolant Temperature Shutdown | Blockage in radiator | Check radiator shroud and ducting for blockage and remove any foreign matter. |
| High Coolant Temperature Shutdown | Leakage in coolant hoses, engine block, or water pump | Inspect for visible leaks. Check tension of water pump serpentine drive belt. Remove load on generator and restart engine. Check coolant temperature and shut engine down immediately if it starts to overheat (230 degrees or higher). See the engine operator's manual for additional information on engine overheating. |
| Overcrank Shutdown | Fuel level low | Check fuel level in tank. Check fuel pump operation. Check air filter for blockage. See engine operator's manual for additional information. |
| Overspeed or Underspeed Shutdown | Frequency setting incorrect | Disconnect all loads and restart unit. Read frequency (Hz) in the LCD window on controller. Frequency should read 60 Hz. If frequency is above 60 Hz, engine speed will need to be adjusted. Contact Isuzu to adjust speed. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Parts
11| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 12142 | Decal, ground | 1 | Service part / kit | Amazon eBay NAPA $74.66 |
| 22870 | Decal, Caution for 480V CSA | 1 | Service part / kit | Amazon eBay |
| 23827 | Decal, Controller Switches | 1 | Service part / kit | Amazon eBay |
| 23846 | Decal, Controller Instructions | 1 | Service part / kit | Amazon eBay |
| 24942 | Decal, Patented 7,642,665,B2 | Service part / kit | Amazon eBay | |
| 26286 | Decal, Hood Service | 1 | Service part / kit | Amazon eBay FridayParts $229.95 |
| 26386 | Decal, Pinch Point | 1 | Service part / kit | Amazon eBay NAPA $45.89 |
| 26387 | Decal Set, Rear Hood Latch | 1 | Service part / kit | Amazon eBay FridayParts $18.23 |
| 27733 | Decal, Interior Light Switch Option | Service part / kit | Amazon eBay | |
| 30175 | Decal, UN31A tank caution | 1 | Service part / kit | Amazon eBay NAPA $12.21 FridayParts $85.00 |
| 30496 | Decal, 3 Pos Phase Switch Located on Manual Holder. | Service part / kit | Amazon eBay FridayParts $16.50 |
Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.
Available documents
Owner's manual — 24594 (Generac)Owner's manual — 29663 (Generac)Parts manual — 28614 (Generac)
This page was generated from the 3 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.