Are you frustrated because your generator won’t start when you need it most? Whether it’s a backup generator for emergencies or a portable unit for outdoor use, a generator that refuses to power on is a serious inconvenience. Fortunately, many common generator problems have simple fixes.
At Koch & White, we help homeowners across Ann Arbor with reliable generator repair and maintenance services. Here are the most frequent reasons your generator is not starting—and what you can do about it.
One of the top reasons a generator won’t start is a dead battery or loose battery cables. Like a car, most generators rely on battery power to start up. If the battery has lost its charge or the terminals are corroded, your unit might not respond at all.
Generator troubleshooting tip:
Use a multimeter to check for ~12.6 volts on a fully charged battery.
Ensure cables are clean and tight.
Replace the battery if needed—bring the old one to match specifications.
Wondering why your generator won’t start after sitting unused for months? Old fuel is a likely culprit. Common generator problems include stale gasoline that has lost its combustibility.
Generator maintenance tip:
Gasoline lasts 3–6 months; diesel can last up to a year.
Drain old fuel into a safe container and refill with fresh fuel.
For standby units connected to a permanent gas line, this isn’t an issue.
A dirty air filter restricts airflow and can choke your generator’s engine. While it might not fully stop the unit from starting, it can cause poor performance and fuel waste.
Generator maintenance tips:
Replace the filter once a year—or more often in dusty conditions.
If the engine starts but sputters or runs weak, the filter could be the cause.
A bad spark plug is another common reason a generator is not starting. If it can’t produce a strong enough spark to ignite the fuel, the engine won’t turn over.
Signs of a spark plug problem:
Black carbon buildup on the tip
Rough starts or failure to start
How to fix it:
Disconnect the plug wire, remove the old plug with a wrench, and replace it with a new one that matches your model.
If your generator starts but shuts down or won’t supply power, you could have a tripped breaker or blown fuse. This can happen during an overload, especially with standby models.
Check the manual for the breaker or fuse location.
Reset the breaker or replace the fuse if needed.
Some models may require a full system reset (battery disconnect).
Skipping regular service is one of the most overlooked reasons a generator won’t start. Preventive care keeps your system reliable and extends its lifespan.
Top generator maintenance tips:
Change the oil, oil filter, and fuel filter annually
Clean or replace spark plugs
Inspect the battery and cables
Run the generator monthly to keep components lubricated
Even if you handle basic tasks yourself, it’s smart to schedule professional generator maintenance every 1–2 years.
Tried the tips above, but your generator still won’t start? Or maybe you’re not quite comfortable checking the battery, draining fuel, or replacing spark plugs on your own—we get it. While some generator troubleshooting steps are safe and manageable for handy homeowners, not every fix is DIY-friendly.
That’s where we come in.
At Koch & White, we specialize in whole-home generator repair, diagnostics, and preventative maintenance. Our trained technicians have the experience and tools to quickly identify why your generator isn’t starting and get it back up and running fast.
We’re also here to help you stay ahead of future problems. With our generator maintenance services, we can:
Replace worn parts like filters and spark plugs
Test voltage and fuel system performance
Perform deep system checks that go beyond basic DIY steps
You rely on your generator for peace of mind—don’t wait until the next outage to find out it’s not working.
Contact Koch & White today to schedule your generator installation, repair, or routine maintenance in Ann Arbor. We’ll make sure your system is ready whenever you need it most.
