How to Troubleshoot a Faulty Commercial Standby Generator

How to Troubleshoot a Faulty Commercial Standby Generator


Standby generators are essential backup systems that provide emergency power when the main power source fails. Commercial standby generators are large units designed to supply emergency power to businesses, hospitals, data centers, and other facilities. Like any complex machine, standby generators can develop issues that prevent them from operating properly when needed. As the owner or operator of a commercial facility, it's important to understand how to troubleshoot common standby generator problems so you can quickly restore backup power if the main utility supply goes down. This article provides a step-by-step guide to diagnosing and resolving the most frequent causes of standby generator failures.

Safety Precautions

Before beginning any troubleshooting or repair work on a commercial standby generator, it's critical to follow safety protocols. Generators contain dangerous high voltages and moving parts that can cause severe injury if proper precautions aren't taken.

Basic Troubleshooting Steps

Begin basic generator troubleshooting by following these steps:

Inspect the Generator Exterior

Check All Fluids

Review Maintenance Records

Inspect Batteries

Check Control Panel

Common Standby Generator Faults

If basic troubleshooting steps don't uncover the issue, consider these frequent generator malfunctions:

Failure to Crank

The starter motor fails to turn over the engine when the generator is signaled to start.

Failure to Start

The starter motor cranks but the engine doesn't start.

Surges and Fluctuations

Engine runs irregularly with oscillations in voltage and frequency.


Engine constantly runs hot; temperature gauge in red.

No AC Output

Generator runs but won't supply AC power.

Unusual Noise/Vibration

Generator has grinding, knocking, squealing, or shaking while running.

When to Call for Generator Service

For major generator problems like seizing engines or significant electrical faults, the best option is to contact the generator manufacturer or an authorized service dealer. Most manufacturers provide 24/7 emergency service for critical standby power systems. Trained technicians have the expertise to fully evaluate and repair complex generator malfunctions beyond typical operator troubleshooting capabilities.


Regular standby generator testing and maintenance is the best way to prevent failures when emergency power is needed. But even well-maintained generators can experience issues. Knowing how to perform basic troubleshooting steps can help minimize downtime. For significant generator problems, don't hesitate to call the manufacturer's service department to get your backup power running again quickly. Proper generator maintenance and servicing will ensure your system provides reliable emergency power for years to come.