Generator Won't Stay Running
In This Guide
A generator won't stay running is one of the more maddening faults, the machine fires up willingly, runs for a few seconds or minutes, then quits just when you need it. That behaviour is telling you something specific: it can get started but cannot sustain itself, and that points almost entirely at the fuel supply. Here is how to find which link in the fuel chain is failing.
The Telltale Clue: It Runs on Choke
Here is the single most useful diagnostic. Does the generator keep running as long as the choke is on, then die when you turn the choke off?
If so, that is almost a definitive sign of a partially blocked carburetor. The choke restricts air, creating a richer mix that compensates for a fuel passage that is partly clogged. Turn the choke off, the mix leans out, the blocked jet cannot supply enough fuel, and the engine starves and dies.
Cause 1: A Partially Blocked Carburetor
The leading cause by a wide margin. Stale fuel leaves varnish that partly blocks the carburetor jets. There is enough flow to start, particularly with the choke's help, but not enough to keep the engine running once it is warm and the choke is off.
The fix is a carburetor clean, clearing the jets and passages so full fuel flow returns. Our carburetor cleaning guide covers the process.
Cause 2: The Low Oil Shutdown
Almost every generator has a low oil sensor that stops the engine to protect it. If the oil is low, or the generator is on a slope that makes the sensor read low, the engine will start then cut out after a few seconds.
Check the oil on level ground and top it up if needed. This is a genuinely common and easily missed cause.
Cause 3: A Clogged Fuel Cap Vent
This one surprises people. The fuel cap has a small vent that lets air into the tank to replace the fuel being used. If that vent is blocked, a vacuum builds in the tank as the engine draws fuel, until fuel can no longer flow and the engine starves and stops.
Cause 4: Fuel Delivery Restrictions
Anywhere the fuel is restricted on its way to the carburetor can cause the same starvation: a clogged fuel filter, a kinked or perished fuel line, or debris in the tank. Each limits flow enough to start but not to sustain running.
Cause 5: A Dirty Air Filter
Less common for an outright stall, but a badly clogged air filter chokes the air supply, upsets the fuel-air mix, and can cause rough running and stalling. It is quick and cheap to check, so rule it out early.
The Order to Check In
1. Check the oil level
On level ground. Rules out the low oil shutdown.
2. Try loosening the fuel cap
Rules the vent in or out in seconds.
3. Check the air filter
Quick and cheap.
4. Does it only run on choke?
If yes, clean the carburetor. This is the most likely fix.
5. Check fuel filter and lines
For restrictions if the carburetor is clean.
Rather Have a Real Technician Handle It?
A Wildwood technician comes to your home, diagnoses the generator on site, and gets it running, usually in about an hour. More than 10,000 repairs completed since 2019, with flat rates quoted before we arrive so there are no surprises. When you need power back, you need it back now.