Troubleshooting a Toro Lx420

The LX420 is a tractor mower designed for cutting grass released by the Toro company in 2010. The tractor features an 18-horsepower Kohler twin-cam engine with automatic transmission and cruise control. It has a maximum speed of 5.5 miles per hour (mph) with a 3-gallon fuel capacity and can cut grass up to 50 inches high. Occasionally, the tractor may encounter problems with starting, stalling or cutting. Simple troubleshooting can sometimes prevent costly repairs, allowing you to diagnose and fix a minor problem associated with your LX420.

Engine Stalling/Not Starting

Step 1

Place the power take-off (PTO), also known as the blade engage lever, in the "Off" position to prevent the engine from starting for safety reasons. Check the parking brake; if you have not applied it, do so and restart the engine.

Step 2

Check your spark plugs to ensure they are all connected. Inspect the spark plugs, and change them if they appear worn or you have yet to change them after more than two years of consistent use. Get back on the tractor, move the throttle/choke control into the "Choke" position and restart the engine.

Step 3

Inspect the fuel lines if the engine still fails to start. A crimped or leaking fuel line is not only dangerous but can prevent adequate gas to flow into the engine for it to start. Check the fuel level as well, and fill the tank if it appears too low.

Step 4

Turn the engine on with the throttle in the "Fast" position as your last resort. The engine may have flooded; to start it again, you must apply the throttle in this fashion.

Step 5

Replace the engine oil if the motor smokes and begins to overheat. The airflow to the engine may also be clogged and restricted. Clean the areas of debris near the cooling fan, located in the front of the mower's engine block.

Mowing Problems

Step 1

Sharpen or replace the blade if it is not cutting through the grass. Inspect the blade for rust, which may indicate the need for a replacement if sharpening fails to fix the problem.

Step 2

Increase the engine speed if the mower does not mulch the grass. Place the throttle in the "Fast" position to attempt to fix the problem. Do not attempt to cut wet grass; the mower will not cut it properly.

Step 3

Perform a deck adjustment as indicated in your owner's manual if the tractor appears to cut grass unevenly; the cutting deck may be improperly balanced. Tighten the blade if the mower seems to vibrate as it cuts.