If a generator runs out of fuel, it simply stops running and your home loses the backup power it was providing, returning you to the outage. What actually happens depends on your generator’s fuel type, since a natural gas generator connected to a utility line does not run out under normal conditions, while propane and other tank-fueled generators run only until their tank is empty. Understanding this helps you avoid being caught without power.

Here is what happens to a generator if the gas runs out.

It shuts down

At the basic level, when a generator runs out of fuel, the engine stops and it can no longer generate electricity. Since a standby generator only runs during an outage, this means your home returns to being without power until the fuel is replenished and the generator restarts. The generator is not powering your home once it has no fuel to run on.

By fuel type

The likelihood and behavior of running out of fuel depends on what the generator runs on:

• Natural gas. A generator connected to your utility natural gas line has an essentially continuous supply, so it does not run out of fuel under normal conditions. It would only stop if the gas supply itself were interrupted, which is uncommon.
• Propane. A propane generator runs until its tank is empty, then shuts down. During a long outage, the tank level needs to be monitored so it can be refilled before running dry.
• Diesel or gasoline. These run until the fuel tank is empty and then shut down, requiring refueling to continue.

This is a major reason natural gas is popular for home standby generators, since a continuous supply avoids the risk of running out.

Restarting after refueling

Once fuel is restored, a standby generator can start running again. Depending on the model and setup, it may restart automatically when it senses fuel and the outage is ongoing, or it may need to be restarted. Modern standby generators are designed to shut down and start up in a controlled way, which protects the engine.

Does running out of fuel damage the generator?

Simply running out of fuel and stopping does not typically damage a well-maintained standby generator, since it is designed to stop when fuel is unavailable. However, running dry is not ideal as a routine occurrence, and for diesel systems in particular, running completely out can require additional steps to restart. The best practice is to avoid running out in the first place.

How to avoid running out

To keep your generator running through an outage:

• For propane, monitor the tank level during extended outages and arrange refills before it runs low.
• For diesel or gasoline, keep the tank adequately fueled and refuel as needed.
• For natural gas, you generally do not need to worry about running out, since the supply is continuous.
• Have your generator and fuel system professionally maintained so it runs efficiently.

If a generator runs out of fuel, it shuts down and stops powering your home until it is refueled. Natural gas generators connected to a utility line do not run out under normal conditions, while propane, diesel, and gasoline generators run only until their tank is empty. Running out simply stops the generator rather than typically damaging it, but the best practice is to monitor tank-fueled units during long outages and keep them supplied.

Stella Electric installs and services standby generators, including natural gas units with continuous fuel, for homeowners across the Baltimore area and throughout Maryland, with flat-rate pricing and no overtime charges. We will help you set up reliable backup power. Financing is available on qualifying projects.