Graham FisherBy Graham Fisher

Updated November 2026

A TB230 lawn mower that won’t start usually comes down to one of a handful of causes: stale fuel, a fouled spark plug, a clogged air filter, or a safety interlock that isn’t engaged. This guide walks through those checks in the order that solves the problem fastest, so you can get the mower running without guessing. Work through the steps in sequence and stop as soon as the engine fires.

Check the Fuel and Oil First

Most no-start complaints on Troy-Bilt walk-behind mowers trace back to fuel. Gasoline that has sat for more than about 30 days can turn varnishy and block the carburetor jets, and ethanol-blended fuel absorbs moisture over time. Look at the fuel tank before anything else.

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  • Confirm the tank has fresh gasoline. If it smells sour or looks dark, drain it into an approved container and refill.
  • Check the fuel shutoff valve, if your model has one, and make sure it is open.
  • Check the oil level on the dipstick. Many mowers have a low-oil shutdown sensor that stops the engine before it starts.

Inspect the Spark Plug and Ignition

If the fuel is fresh, the next suspect is the spark. Remove the spark plug boot, unscrew the plug, and look at the electrode. A black, sooty tip suggests a rich fuel mixture or a dirty air filter. A white or blistered tip suggests overheating. Both mean the plug should be replaced.

  1. Disconnect the spark plug wire and pull it firmly from the plug.
  2. Remove the plug with a spark plug socket and inspect the tip.
  3. Clean or replace the plug, then set the gap to the value listed in your owner’s manual.
  4. Reconnect the wire, make sure it is seated, and try to start the mower.

If the plug looks healthy and does not spark when you ground the body against the engine, the ignition coil or wiring may be at fault. That is a job for a small-engine technician.

Clear the Air Filter and Choke Settings

A restricted air filter starves the engine of air, so the mixture runs too rich and the engine bogs or refuses to fire. Remove the filter cover and check the element. Paper filters should be replaced when dirty, and foam filters can be washed and re-oiled.

Next, check the choke. A cold engine needs the choke closed to start, but once it has fired, the choke should be opened quickly. Leaving the choke closed on a warm engine floods it with fuel and causes the same no-start symptom. Try starting with the choke at the position your manual specifies for a cold start, then move it to run as soon as the engine catches.

Verify the Safety Interlocks

Push mowers with a bail or blade-engagement system will not crank unless the controls are in the correct position. Make sure the bail is pressed firmly against the handle and that any blade-engagement lever is in the off position before you pull the starter cord. A switch that is out of adjustment or a loose connector can also prevent starting, so inspect the wiring near the switches for damage.

Common Mistakes

  • Pulling the starter cord repeatedly with a flooded engine. Wait a few minutes, remove the spark plug, and dry it before trying again.
  • Replacing the spark plug without checking fuel first. Fresh fuel is the cheaper test.
  • Ignoring the air filter because it looks clean on the outside.
  • Leaving old gasoline in the tank over winter. Use fuel stabilizer or run the carburetor dry before storage.

A basic spark plug socket with a rubber insert makes plug removal much safer on a hot engine and prevents the porcelain from cracking. View on Amazon

A fuel stabilizer helps keep gasoline usable between seasons and reduces the chance of carburetor gum. View on Amazon

FAQ

How old can gasoline be before it stops working?

Gasoline older than about 30 days can start to degrade, especially ethanol blends. If the fuel has been sitting over a season, drain it and refill with fresh fuel before troubleshooting further.

Can I start the mower with the spark plug removed to check spark?

You can ground the plug body against the engine while cranking to see if a spark jumps the gap, but keep your hands clear of the plug and wire. If you are unsure, have a technician check the ignition.

Why does my mower start and then die right away?

This usually points to a choke left closed, a clogged carburetor jet, or a fuel delivery problem. Open the choke after startup and check fuel freshness and the air filter.

Conclusion

Most TB230 no-start problems come down to fuel, spark, air, or a safety switch, and you can check all four with basic tools. Work through the checks in order and you will usually find the cause within the first two or three steps. For related models with similar symptoms, see Troy Bilt TB210 Lawn Mower Won't Start: 8 Causes and Fixes and Troubleshooting a Lawn Mower That Won't Start: 8 Steps to Fix It.

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Graham Fisher

About Graham Fisher

Graham Fisher is part of our editorial team and reviews and edits our lawn mowers guides, checking product details against manufacturer specifications and owner feedback.