The Generac GP15000E is a serious piece of equipment — with 15,000 running watts and 22,500 starting watts, it’s built to handle everything from whole-home backup to heavy-duty job site power. While it’s one of the most powerful portable generators on the market, owners have noted a few recurring issues over years of use. Understanding these problems, why they happen, and how to prevent them can help you get the most out of your investment.
Common Generac GP15000E Problems
1. Hard Starting or No Start
Given its size, the GP15000E’s big OHVI engine needs a healthy battery and proper fuel delivery to start reliably. Some owners report trouble starting after long storage periods or in cold weather.
- Possible Causes: Weak or dead starting battery, stale fuel, clogged carburetor, or incorrect choke position.
- Prevention: Keep the battery charged with a trickle charger, use fresh fuel, and run the generator monthly.
- Solution: Charge or replace the battery, clean the carburetor, and ensure proper choke operation before starting.
2. Fuel Consumption
With a massive 992cc engine, the GP15000E burns a lot of fuel, especially at high load. Some owners are surprised at how quickly it drains its large 16-gallon tank.
- Possible Causes: Running continuous heavy loads, leaving non-essential devices powered during operation.
- Prevention: Use load management — power only the essentials at one time.
- Solution: Run in stages to reduce total consumption during long outages.
3. High Noise Levels
This generator is not quiet. At around 83 dB under load, it can be disruptive in residential neighborhoods or for extended work shifts on job sites.
- Possible Causes: Large displacement engine and open-frame design.
- Prevention: Place the generator as far from living or work areas as possible.
- Solution: Use sound barriers or enclosures rated for generator ventilation.
4. Heavy and Difficult to Move
Weighing over 350 pounds, the GP15000E is technically portable — but only if you have the right terrain and strong help. Even with wheels and handles, maneuvering on grass or gravel is tough.
- Possible Causes: Sheer size and weight of components needed for 15,000 watts.
- Prevention: Store it in a spot where minimal movement is needed for use.
- Solution: Consider a permanent pad and connection point to reduce frequent relocation.
5. Overload Shutdowns
With so much available power, it’s tempting to plug in everything at once. However, certain combinations of high-surge appliances can trigger the overload protection, shutting the generator down.
- Possible Causes: Appliances with high starting wattages (AC units, compressors) exceeding momentary capacity.
- Prevention: Start large loads one at a time.
- Solution: Use a transfer switch with load-shedding capability to prevent overload trips.
6. Maintenance Neglect
Several reported issues come down to skipped oil changes, dirty filters, or infrequent running. With an engine this size, neglect can quickly lead to performance loss or damage.
- Possible Causes: Infrequent servicing, ignoring manufacturer’s maintenance schedule.
- Prevention: Follow recommended service intervals — oil every 50–100 hours, air filters every 100–200 hours, etc.
- Solution: Keep a maintenance log and perform preventative care before peak storm seasons.
Owner Feedback and Observations
Despite these potential problems, many owners praise the GP15000E for:
- Massive power output — runs entire homes or demanding job sites
- Electric start convenience
- Solid, durable build quality
- Long run times at partial load (up to 10 hours on 50%)
The trade-offs are clear: you get unmatched portable power, but you also deal with significant fuel use, high noise, and the need for careful load planning.
Tips for Avoiding Common GP15000E Issues
- Run the generator monthly for at least 15 minutes under load
- Keep fuel fresh and use stabilizer if storing gasoline more than 30 days
- Charge the battery regularly to ensure reliable starts
- Plan loads to avoid overloading circuits
- Perform oil and filter changes on schedule
When Even a GP15000E Isn’t Enough
While the GP15000E offers serious muscle, it still depends entirely on gasoline. In a long-term outage where fuel supply is limited, even a large tank will eventually run dry — and refueling might be difficult or impossible.
The Ultimate OFF-GRID Generator
The Ultimate OFF-GRID Generator is an untapped source of on-demand electricity that runs quietly, produces no emissions, and never needs refueling. It’s ideal for keeping essentials like lights, phones, and medical devices running indefinitely, while the GP15000E handles high-wattage jobs when fuel is available.
Combining the two creates a layered backup power strategy — renewable, fuel-free electricity for continuous needs, and powerful gasoline-driven output for peak demand.
The Bottom Line
The Generac GP15000E is a powerhouse portable generator, but it’s not without its challenges. Expect high fuel use, loud operation, and heavy weight — all trade-offs for its massive capacity. With proper maintenance and load planning, it can be a dependable workhorse for years. For true long-term resilience, pair it with a renewable option like the Ultimate OFF-GRID Generator.
Click here to learn more about the Ultimate OFF-GRID Generator and see how it can complement your GP15000E for complete outage protection.