7 Signs of Bad Fuel Injectors on a John Deere Tractor

A John Deere diesel can run for thousands of hours, but the fuel injectors do wear. When they start to fail, the tractor usually gives you clear warning signs.

The seven signs

1. Hard starting

If the engine cranks for a long time before it fires, especially on a cold morning, leaking or clogged injectors are a common cause.

2. Black smoke

Black smoke usually means too much fuel is being sprayed or not burning cleanly, which points to a worn or dirty nozzle.

3. White or grey smoke

Unburnt fuel passing through the engine can show as white or grey smoke, often from an injector that is stuck open or dribbling.

4. Rough idle

If the engine shakes or hunts at idle, one cylinder may not be getting a proper spray.

5. Loss of power

A tractor that struggles on a hill or under load, when it used to pull easily, may have weak injectors.

6. Poor fuel economy

Burning more diesel for the same work is a sign the injectors are not atomising fuel properly.

7. Diesel knock

A sharp knocking sound can mean an injector is delivering fuel at the wrong moment or in the wrong pattern.

What to do next

Check your fuel filters first, since dirty fuel damages injectors quickly. If the symptoms continue, have the injectors tested. Worn injectors are best replaced as a set so all cylinders stay balanced.

See our John Deere parts page or the general diesel fuel injectors page.