- Check the fuel system. Fuel-related problems are often the reason why a ATV won’t start. Look for kinks or leaks in the fuel lines and check that the fuel filter is clean. Try draining the carburetor bowl to get rid of any water that might have accumulated. Ensure the fuel valve is open.
- Check the ignition system. Make sure the spark plug is installed correctly and is gapped correctly. Check the ignition coil and spark plug wire for damage.
- Check the air filter. A dirty or clogged air filter can restrict airflow and prevent the engine from starting. Clean the air filter and ensure that it is seated correctly in the airbox.
- Check the compression. Low compression can prevent the engine from starting. Use a compression tester to measure the compression in the cylinder. If the compression is too low, it may indicate a worn piston ring, damaged cylinder, or other engine problems.
- Check the battery. A weak or dead battery can prevent the engine from cranking over. Check the battery voltage and charge it if necessary.
If you have tried all of these steps and your TRX250 still won’t start, you may need to take it to a mechanic for further diagnosis and repair.
