Why Keeping Old Fuel in a Generator Is Bad

You invested in a generator to protect your family from the cold and dark during a power outage. But when the lights finally flicker out, and you hit the start button, nothing happens. The culprit is often simple: the fuel sitting in the tank. Learn the risks of stale fuel so you can ensure your generator runs when you need it most. Here’s why keeping old fuel in a generator is bad.

Fuel Degrades Over Time

Gasoline doesn’t get better with age. Modern fuel blends begin to break down in as little as 30 days. As the lighter, more volatile components evaporate, the fuel loses its ability to ignite easily. This degradation makes starting your engine difficult, or even impossible, during an emergency.

It Clogs Carburetors and Fuel Lines

As fuel deteriorates, it leaves behind sticky varnish and gum deposits. These substances coat the inside of your carburetor and narrow the fuel lines. This can cause restricted flow, engine surging, and costly repairs.

Gum buildup can prevent the proper amount of fuel from reaching the engine, and your generator may run unevenly or stall repeatedly. A mechanic must manually clean or replace these gummed-up components. Internal damage turns a reliable backup system into a frustrating lawn ornament.

Moisture Accumulation Causes Corrosion

Old fuel often attracts moisture from the air, especially in the damp climate of the Pacific Northwest. Water is heavier than gas, so it sinks to the bottom of the tank where the fuel pickup line sits. When your generator tries to burn this water-fuel mix, it creates internal corrosion and rust. That rust can flake off and travel through the engine, causing severe damage to pistons and cylinders.

Prevention Saves Money and Stress

You can avoid these headaches. Using a fuel stabilizer can extend the life of your gasoline for up to a year. However, the most effective strategy is to perform regular maintenance. Professional backup generator installers recommend scheduling annual service to drain old fuel and inspect the system.



Keeping old fuel in a generator is bad because it makes your generator unreliable. Don’t let a few gallons of bad gas leave your home without power. Make sure your generator starts every time by contacting NW Generators today to schedule your maintenance appointment.