Compare Generators Side-by-Side
Select up to 4 generators to compare specs, power output, noise levels, runtime and more. Your compare URL is shareable.
- Cummins Onan P4500i
- Firman T04073
Quick charts
Each chart uses its own Y-axis scale (so numbers are comparable within a chart).
Running watts
W
Starting watts
W
Noise
dB
Runtime @50%
h
Running watts by fuel
Shows how output changes across gasoline/propane/natural gas (when available).
| Specification | Cummins Onan P4500i | Firman T04073 |
|---|---|---|
| General | ||
| Product type | Generator | Generator |
| Fuel | Gasoline | Tri-Fuel |
| Inverter | Yes | No |
| Parallel capable | Yes | No |
| RV ready | Yes | No |
| Running watts | 3700 W | Winner: Winner: 4000 W |
| Starting watts | 4500 W | Winner: Winner: 5000 W |
| Noise (lower limit) | Winner: Winner: 52 dB | 67 dB |
| Weight | Winner: Winner: 98 lbs | 123.4 lbs |
| Run time @50% load | Winner: Winner: 15 h | 12 h |
| Run time @25% load | 18 h | 14 h |
| Fuel tank | 3.4 gal | 5 gal |
| Fuel gauge | Yes | Yes |
| Approx. dimensions (L × W × H) | 24.5 x 18.3 x 20.5 | 29.8 x 27.5 x 26.1 |
| Electrical | ||
| Voltage (AC) | 120 | 120/240 |
| Voltage (DC) | 5 | Not available |
| GFCI outlets | No | Yes |
| Covered outlets | Yes | Yes |
| Automatic Voltage Regulation | Yes | Yes |
| THD | 3 % | 11%-14% % |
| Engine | ||
| Engine | 224 cc Ducar OHV 4-stroke | 223 cc OHV 4-stroke, cast iron sleeve |
| Alternator | Not available | Not available |
| Starting system | Recoil; Electric; Remote | Recoil, Electric |
| Warranty | ||
| Warranty | 3 years | 3 years |
| Power by fuel | ||
| Gasoline | Not available | Not available |
| Running watts | 3700 W | 4000 W |
| Starting watts | 4500 W | 5000 W |
| Running amps (120V) | Not available | Not available |
| Running amps (240V) | Not available | Not available |
| Peak amps (120V) | Not available | Not available |
| Peak amps (240V) | Not available | Not available |
| Run time @50% load | 15 h | 14 h |
| Run time @25% load | 18 h | Not available |
| Natural gas | Not available | Not available |
| Running watts | Not available | 3200 W |
| Starting watts | Not available | 4000 W |
| Running amps (120V) | Not available | Not available |
| Running amps (240V) | Not available | Not available |
| Peak amps (120V) | Not available | Not available |
| Peak amps (240V) | Not available | Not available |
| Run time @50% load | Not available | Not available |
| Run time @25% load | Not available | Not available |
| Propane | Not available | Not available |
| Running watts | Not available | 3600 W |
| Starting watts | Not available | 4500 W |
| Running amps (120V) | Not available | Not available |
| Running amps (240V) | Not available | Not available |
| Peak amps (120V) | Not available | Not available |
| Peak amps (240V) | Not available | Not available |
| Run time @50% load | Not available | 9 h |
| Run time @25% load | Not available | Not available |
| Other | ||
| Data center | Not available | Not available |
| Indicators | true | true |
| Compliance | CARB, EPA | CARB, EPA, ANSI/PGMA G300-2023 |
| Security | Not available | Not available |
| Spark arrestor | Yes | Yes |
| Neutral | Floating | true |
| UPC | 690781007925 | 840876140734 |
| Core / High-priority specs | ||
| Running Watts (Gasoline) | 3700 | 4000 |
| Running Watts (Propane) | Not available | 3600 |
| Running Watts (Natural Gas) | Not available | 3200 |
| Starting Watts (Gasoline) | 4500 | 5000 |
| Starting Watts (Propane) | Not available | 4500 |
| Starting Watts (Natural Gas) | Not available | 4000 |
| Runtime @ 50% Load (Gasoline) | 15 | 14 |
| Runtime @ 50% Load (Propane) | Not available | 9 |
| Runtime @ 25% Load (Gasoline) | 18 | Not available |
| AC Outlet Types | 1x Duplex 120V 20A (5-20R); 1x 120V 30A (TT-30R) | 1x Duplex 120V 20A (5-20R) GFCI; 1x 120V 30A (L5-30R); 1x 120/240V 30A (L14-30R) |
| Electrical & power | ||
| Frequency | 60 | 60 |
| Engine & construction | ||
| Engine Type | Ducar OHV 4-stroke | 223 cc OHV 4-stroke |
| Engine Displacement | 224 | 223 |
| Cylinder Sleeve | Not available | cast iron |
| Engine Oil Type | 10W30 | Not available |
| Runtime & fuel system | ||
| Runtime @ 25% Load (Gasoline) | 18 | Not available |
| Runtime @ 50% Load (Gasoline) | 15 | 14 |
| Runtime @ 50% Load (Propane) | Not available | 9 |
| Safety & compliance | ||
| Overload Protection System | Low oil and overload protection | Low oil and overload protection, CO monitoring |
| Low Oil Protection | Yes | Yes |
| Carbon Monoxide Monitoring | No | Yes |
| Included equipment | ||
| Starting Components | Not available | Recoil, Electric |
| Included Accessories | Oil, funnel, tool kit, key fob, battery charger, and battery | Oil, funnel, tool kit, propane hose, RV adapter, cover, battery, and wheel kit |
| Warranty & identification | ||
| Commercial Warranty | 3 | 3 |
| Part Number | A058U955 | Not available |
| Additional specs | ||
| Summary | The Cummins Onan P4500i is a 3700-watt inverter generator built for users who need reliable power without the noise penalty. Its 4500-watt peak capacity handles startup surges for air conditioners, power tools, and RV air conditioning units. The gasoline engine runs clean enough for sensitive electronics like laptops and phones, thanks to a 3 percent THD rating that protects against voltage spikes. This unit bridges the gap between portable camping generators and stationary backup power, making it useful for RV owners, homeowners facing extended outages, and contractors working near occupied spaces. | The Firman T04073 is a 4,000-watt tri-fuel generator that runs on gasoline, propane, or natural gas. On gasoline, it delivers 5,000 starting watts and 4,000 running watts, enough to power a refrigerator, microwave, and multiple household circuits simultaneously. On propane, output drops to 3,600 running watts, and on natural gas it falls to 3,200 running watts. This fuel flexibility means users can switch between sources based on availability and cost, a significant advantage during extended outages or in remote locations where one fuel type may be scarce.
The T04073 targets homeowners, RV owners, and job site operators who need reliable backup power without the commitment to a single fuel source. Its 5-gallon tank runs for 14 hours at 25% load on gasoline, translating to roughly one week of emergency backup if you run it a few hours per day. The unit includes a wheel kit, making it easier to position despite its 123.4-pound weight. |
- Most PowerfulFirman T040734000W running
- QuietestCummins Onan P4500i52 dB
- Longest RuntimeCummins Onan P4500i15h at 50% load
Where to buy
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Cummins Onan P4500i
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Firman T04073
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