Generator Surging or Hunting? Causes and Fixes
A generator that surges or hunts, its engine speed rising and falling rhythmically, usually has a dirty carburetor from stale fuel, a governor problem, or a fuel or air restriction, so it cannot hold a steady speed. A gummed carburetor is by far the most common cause. Stale fuel varnishing the carburetor causes most surging, so cleaning the carburetor fixes the majority of cases.
A generator that revs up and down on its own, called surging or hunting, cannot hold the steady speed it needs to make clean power, so tracing generator surging matters, especially before you rely on it in a Tampa storm outage. The governor tries to hold engine speed constant, and surging means it cannot, usually because a gummed carburetor from stale fuel is disrupting the fuel flow. Less often the governor itself or a restriction is at fault. This guide runs the causes and fixes.
What Surging Is
Surging is the engine speed rising and falling on its own.
The generator’s governor holds the engine at a set speed so the output stays steady. Surging, or hunting, is when the engine repeatedly speeds up and slows down instead of holding steady, so the power output rises and falls too. It usually means the engine is not getting a consistent fuel and air mix, most often because the carburetor is partly clogged, so the governor keeps overcorrecting.
The Carburetor Is Usually It
A gummed carburetor from stale fuel causes most surging.
Fuel and Air Restrictions
Anything restricting fuel or air can cause surging.
| Cause | Fix |
|---|---|
| Clogged carburetor jets | Clean the idle and main jets and passages |
| Dirty air filter | A clogged filter upsets the mix; clean or replace it |
| Restricted fuel flow | A clogged fuel filter, kinked line, or blocked cap vent starves it |
| Stale or wrong fuel | Old or ethanol heavy fuel; use fresh, treated fuel |
The Governor
If fuel and air are clean, the governor may be the cause.
The Takeaway
To recap: generator surging is the engine hunting up and down because it cannot get a steady fuel and air mix, most often from a gummed carburetor from stale fuel, and sometimes a dirty air filter, a fuel restriction, or a governor issue. Clean the carburetor and use fresh fuel first.
Because stale fuel and a gummed carburetor cause most surging, cleaning the carburetor fixes the majority, and fresh treated fuel keeps it from returning.
Before you need it in a Tampa storm, if your generator surges we can clean the carburetor and set the governor at your home. Our repair guide walks through the machine, and the output guide a related no power fault.
Frequently Asked Questions
Why does my generator surge up and down?
Usually a gummed carburetor from stale fuel disrupting the fuel flow, so the governor cannot hold a steady speed and hunts up and down. Less often a dirty air filter, a fuel restriction, or a governor problem. Cleaning the carburetor and using fresh fuel fixes most surging.
How do I fix a surging generator?
Clean the carburetor, especially the idle and main jets, since stale fuel varnish is the most common cause, and refill with fresh, treated fuel. Check the air filter and fuel flow too. If it still surges with a clean carburetor and fresh fuel, the governor adjustment or linkage may be at fault.
What causes a generator to hunt?
Hunting, or surging, is the governor overcorrecting because the engine is not getting a consistent fuel and air mix, most often due to a partly clogged carburetor from old fuel. A dirty air filter, a restricted fuel supply, or a sticking governor linkage can also cause it.
Can stale fuel cause a generator to surge?
Yes, it is the leading cause. Fuel that sat and degraded varnishes the carburetor’s small passages, disrupting the fuel flow so the engine cannot hold a steady speed and surges. Cleaning the carburetor and running fresh, stabilized fuel resolves most of these cases.
Is it safe to run a surging generator?
It is best not to, since unstable engine speed means unstable voltage and frequency that can harm sensitive electronics, and it signals a fuel or governor fault. Fix the surging, usually by cleaning the carburetor, before relying on the generator, especially for a storm outage.
