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A fuel shut-off solenoid is one of the key components that enable the engine to start and stop.

Common problems such as a stuck plunger, bad wiring, or failed internal components may cause various issues within the engine of your John Deere machine, whether riding or zero turn lawn mower.

Keep reading as I share troubleshooting tips to help you diagnose and fix your John Deere fuel shut-off solenoid problems and also, a step-by-step guide on how to test your John Deere fuel shut-off solenoid.

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What is a Fuel Shut-Off Solenoid?

A fuel shut-off solenoid is an electromagnetically controlled valve that allows fuel flow into the injector pump or carburetor.

It is used to remotely start and stop an engine’s fuel flow. Fuel is allowed to flow through the solenoid valve when the solenoid is activated.

Fuel flow is essentially stopped when the solenoid is disengaged because the valve spring forces the poppet back onto its seat.

The shut-off solenoid can be controlled manually or automatically as a component of an engine management system.

How Does the Fuel Shut-Off Solenoid Work?

A shut-off solenoid’s regular state is not activated (i.e. there is no power to it). When it is in this state, fuel cannot pass through.

The solenoid is activated/turned on before the engine starts when you turn the key, which allows fuel to flow into the engine. When this happens, the engine will begin to crank.

The power to the stop solenoid is cut off when the engine is stopped, closing the fuel line and bringing the engine to a complete stop.

To put it another way, if the solenoid loses power while the engine is operating, the fuel supply will be cut off, causing the engine to shut off immediately.

John Deere Fuel Shut Off Solenoid Problems, Diagnosis, and Fixes

If you discover that your fuel shut-off solenoid is defective, it may be caused by one of the following reasons:

1. Bad/Damaged Wiring

One of the most frequent problems with the John Deere shut-off solenoid is damaged wiring.

The shut-off solenoid receives power to activate when the engine is ignited from the wires connected to the ignition system.

One of the wires attached to the solenoid may get disconnected, split, broken, or damaged and stop it from receiving power to crank the engine.

Diagnosis:

Inspect the wires attached to the fuel solenoid. Look for cut, split, or damaged connections.

Fix:

Reattach/repair the disconnected wiring. Replace the solenoid if the wiring is damaged.

2. Stuck Plunger

The plunger can get stuck with debris from fuel debris or metal rust and remain in the closed position even when it has been activated.

This will prevent it from allowing fuel into the engine and your John Deere machine may not start as a result.

Diagnosis:

Turn the key or start switch and watch the solenoid plunger. It should open/move in to allow fuel flow.

If it doesn’t, try using your hand to move the plunger in. If there is resistance, the plunger might be stuck.

Fix:

Spray a penetrating fluid like WD-40 or carburetor cleaner around the plunger to release it.

3. Failed Internal Components

The solenoid may get worn out or damaged after many years of use. The internal electromagnetic system of the solenoid may fail completely making the plunger unresponsive.

Diagnosis:

Test the fuel solenoid. If the plunger doesn’t react after making contact with the battery, the solenoid may be worn or damaged.

Fix:

Replace the solenoid.

How to Test a John Deere Fuel Solenoid

Without the solenoid, your John Deere machine may not start or may shut down soon after starting.

Perform the following test to confirm if the solenoid should be replaced or not.

Tools You Need For This Job

Battery with a minimum output of 9 volts
9volts plug with two cables attached (positive and negative cables)

Step 1: Fiest, attach the plug to the battery terminals

Step 2: Touch the prongs/terminals of the solenoid with the positive and negative wires attached to the 9 volts plug

Solenoid functions similarly to light bulbs in that they work regardless of the direction they are connected.

Because polarity (+/-) can be produced in either direction, you’re unlikely to locate a +/- on the solenoid.

Step 3: As you make contact, watch the action of the solenoid plunger.

Step 4: The plunger should move in indicating that it has been energized. This will enable fuel flow into the engine.

Therefore, when there is a source of 9-volt minimum power to the solenoid, the solenoid magnet pulls up on the plunger and allows fuel into your machine.

The plunger of a bad/damaged solenoid will remain in the closed position. If this results, you will need to replace the solenoid.

What to Do If Your Fuel Shutoff Solenoid Stops Working

If your John Deere fuel shut-off solenoid stops working, it is best to replace it with a new one.

If for any reason, a new fuel solenoid isn’t accessible, you can temporarily bypass the solenoid by removing the solenoid plunger to allow fuel flow.

Then, insert a fuel shut-off valve in the fuel line to stop fuel flow when the engine is not in use.

Symptoms of A Failed Fuel Shut-Off Solenoid

How do I know if my fuel shut-off solenoid is failing or has stopped working?

Some symptoms you may notice when the fuel solenoid fails include:

1. Trouble Cold Starting The Engine

A defective solenoid might create problems starting the engine, which is most obvious when the engine is cold.

It may take some time for the solenoid to get fuel to the combustion chamber. After the engine has started, try turning it off and on again. If restarting it is difficult, the solenoid may be faulty.

2. The Engine Cranks But Does Not Fire

If your John Deere engine cranks but does not start, the solenoid might be to blame.

This is because fuel is required by the engine for it to start. A faulty fuel shut-off solenoid will restrict this fuel flow even after the ignition has been turned on.

3. Unsteady Idling

When idling the engine, you may notice that the engine stops and then emits a strange sound to alert you that there is a problem.

This is due to the solenoid becoming deenergized and suddenly switching off.

4. Power Loss

When driving or engaging the blades on the mower, you may notice a lack of power.

Solenoids do not always fail in the ON/OFF position; they can also become stuck in a halfway position and allow minimum fuel flow.

If the solenoid becomes stuck in the halfway position, you may discover that idling and lower RPMs are satisfactory. However, once the engine is loaded at maximum RPMs, it will become starved and slow down, indicating a faulty solenoid.

5. Engine Suddenly Shuts Down

The engine will shut down if it does not receive fuel. If the engine abruptly stops for no apparent reason, it is likely due to a lack of fuel.

A faulty solenoid may lose energy, causing it to return to the closed position and resulting in a lack of fuel.

Conclusion

The fuel shut-off solenoid may stop functioning effectively due to a wiring problem, failed internal electrical components, or a stuck plunger.

You can now apply the troubleshooting tips in this article to fix your John Deere fuel shut-off solenoid problems and get your engine started again.