Replacing Kohler Fuel Solenoid: Step-By-Step Guide For Diyers

Kohler fuel solenoids are an essential component of small-engine machinery, such as lawn mowers, preventing engines from backfiring during shutdown. When the ignition is turned off, the solenoid blocks fuel flow to the carburetor, preventing excess fuel from entering the combustion chamber and causing an explosive backfire. While Kohler fuel solenoids are generally reliable, they may occasionally need to be replaced due to wear and tear or malfunction. Replacing a Kohler fuel solenoid can be a straightforward process, but it requires careful handling of fuel and battery sources to avoid accidents. This involves testing the solenoid, battery, and fuel supply, and, if necessary, purchasing and installing a replacement solenoid.

How to test a Kohler fuel solenoid

To test a Kohler fuel solenoid, you can follow these steps:

Firstly, lower the throttle to the mid-range position just before shutting down the Kohler engine. For the fuel shut-off valve to work properly, the throttle position should be in the full to mid-range position.

If a backfire occurs despite following the correct shutdown procedure, check for the proper voltage. Test for a minimum of 7 Volts DC at the fuel solenoid terminal using a Volt-Ohm meter. Place one of the meter leads to the solenoid terminal and the second lead to the engine case. Power from the battery shuts the fuel flow off to the carburettor. No power is present on the solenoid while the engine is running.

If there is no (or low) voltage at the solenoid, check the battery for a proper charge and a good battery connection. Test the battery for voltage using the Volt-Ohm meter. Attach the Volt-Ohm meter across the positive and negative battery posts while the engine is shut down. Crank the engine and observe the voltage drop across the battery posts. If the voltage drops below 9 Volts DC, apply a battery charger and bring the battery back to its appropriate charge. Replace the battery if it will not accept a charge.

If these tests do not reveal any problems, remove the fuel shut-off solenoid from the carburettor for further testing. Connect 12 Volts DC power to the solenoid. Connect the negative (ground) lead to the solenoid case and apply the positive (red) lead to the solenoid terminal. If the solenoid does not shift to the "Off" position, the solenoid is faulty and needs to be replaced.

You can also test a Kohler fuel solenoid by removing it from the carburettor and bench-testing it with 12 Volts. It should pull the plunger back with 12 Volts applied and release when you remove the power.

Troubleshooting a faulty Kohler fuel solenoid

Firstly, it is important to understand the function of a fuel shut-off solenoid. This component interrupts the fuel flow from the injection pump when the ignition is switched off, preventing the engine from backfiring and becoming flooded. By blocking the fuel flow to the carburetor when the ignition is off, excess fuel cannot enter the combustion chamber, eliminating the potential for backfiring.

If you are experiencing backfiring, ensure that you are following the correct shutdown procedure by lowering the throttle to the mid-range position before turning off the engine. If backfiring persists, check for proper voltage at the fuel solenoid terminal using a Volt-Ohm meter. Place one of the meter leads to the solenoid's terminal and the second lead to the engine case. If there is no or low voltage, check the battery for a proper charge and a good connection.

Next, test the battery for voltage using the Volt-Ohm meter. Attach the meter across the positive and negative battery posts while the engine is shut down, then crank the engine and observe the voltage drop. If the voltage drops below 9 Volts DC, apply a battery charger to restore the battery's charge. If the battery will not accept a charge, it may need to be replaced.

If the above tests do not reveal any issues, remove the fuel shutoff solenoid from the carburetor for further testing. Connect 12 Volts DC power to the solenoid, connecting the negative (ground) lead to the solenoid case and the positive (red) lead to the solenoid terminal. If the solenoid does not shift to the "Off" position, it is faulty and requires replacement.

Before troubleshooting the fuel shutoff solenoid, it is also recommended to check the fuel supply and fuel filter if the engine fails to start.

Additionally, there are several symptoms that may indicate a faulty fuel shut-off solenoid:

• Engine Shutting Off: A faulty solenoid can cause the engine to shut off unexpectedly due to a disruption in the fuel supply.
• Smoke and Noise: Excessive smoke and noise during engine operation may indicate a faulty solenoid or impaired valves, leading to an abnormal amount of fuel entering the combustion chamber.
• Unsteady Idling: The engine may stall during the idling phase, accompanied by unusual sounds, due to insufficient fuel entering the combustion chamber.
• Cold Start Issues: Difficulty in starting a cold engine may be attributed to the fuel shut-off solenoid not receiving enough current to activate the solenoid plunger.
• Buzzing Sound: A buzzing sound during engine ignition may indicate a problem with the solenoid, requiring prompt attention.
• Trouble When Accelerating: If the mower struggles to receive an adequate fuel supply at maximum RPM, it could be due to a faulty solenoid.
• Valve Malfunction: If the valve fails to open or close properly, it may be due to corrosion, rust, power failure, or dirt within the solenoid system.

To summarise, troubleshooting a faulty Kohler fuel solenoid involves checking for proper voltage, testing the battery, removing the solenoid for further testing, and being mindful of various symptoms that indicate a faulty solenoid, such as engine shutdowns, smoke, and noise.

How to prevent backfiring when shutting down a Kohler engine

Kohler engines are known to backfire when shut down, and this is due to the way the fuel is shut off on the high idle circuit and not the low idle. When the engine is shut down, the fuel solenoid blocks the main jet of the carburetor but not the low-speed idle circuit. As a result, the engine can still pull fuel from the low-speed jet when shut off, causing the backfire.

To prevent backfiring when shutting down a Kohler engine, Kohler recommends shutting down at 1/2 to full throttle. This is because, at the high-speed position, the governor opens the throttle when shut off because the engine is slowing down and tries to get fuel through the high-speed jet, which is blocked by the solenoid, preventing fuel from getting through to the muffler and causing a backfire.

• Bring the throttle down to about 1/4 open, let the engine stabilize, then turn the key off.
• Bring the throttle down to just above idle, let it stabilize, throttle down to idle, let it stabilize, then turn the key off.
• Use non-alcohol fuel or try fuel from a different gas station.
• Change the spark plugs and try using 93 octane fuel.
• Clean the carburetor and add a little Seafoam to the fuel.
• Check for a bad exhaust valve or a too-lean fuel mixture, as these can also cause backfiring.

How to replace a Kohler fuel solenoid

A Kohler fuel solenoid prevents the engine from backfiring by blocking fuel flow to the carburetor when the ignition key is switched to the "Off" position. If your Kohler engine is backfiring, you may need to replace the fuel solenoid. Here's a step-by-step guide on how to replace a Kohler fuel solenoid:

Step 1: Lower the throttle

Before shutting down the Kohler engine, lower the throttle to the mid-range position. The throttle position should be in the full to mid-range for the fuel shutoff valve to work properly.

Step 2: Check for proper voltage

Use a Volt-Ohm meter to test for a minimum of 7 Volts DC at the fuel solenoid terminal. Place one of the meter leads to the solenoid's terminal and the second lead to the engine case. If there is no or low voltage, check the battery for a proper charge and good battery connection.

Step 3: Test the battery

Using the Volt-Ohm meter, check the battery for voltage. Attach the meter across the positive and negative battery posts while the engine is shut down. Crank the engine and observe the voltage drop. If the voltage drops below 9 Volts DC, apply a battery charger to restore the battery to its appropriate charge. Replace the battery if it won't charge.

Step 4: Remove the fuel shutoff solenoid

If the above tests do not reveal any problems, remove the fuel shutoff solenoid from the carburetor for further testing.

Step 5: Connect to a power source

Connect 12 Volts DC power to the solenoid. Connect the negative (ground) lead to the solenoid case and apply the positive (red) lead to the solenoid terminal.

Step 6: Test the solenoid

If the solenoid does not shift to the "Off" position when connected to the power source, it is faulty and needs to be replaced.

Step 7: Replace the solenoid

Purchase a replacement Kohler fuel solenoid that is compatible with your engine model. You can find these at authorised dealers, online stores, or Amazon. Carefully install the new solenoid, ensuring all connections are secure.

Safety Precaution:

Use extreme caution when working around fuel and a battery source. Even a small spark can ignite the fuel.

Where to buy a replacement Kohler fuel solenoid

Kohler fuel solenoids are available from a number of online retailers, including Amazon and Walmart.

Amazon offers a wide range of Kohler fuel solenoids, with prices starting from $9.89. Many of the solenoids are eligible for free delivery on orders over $35. It is worth noting that one customer has warned about the presence of "knock-off parts" on the site.

Walmart also offers a selection of Kohler carburetor solenoids, with prices ranging from $9.89 to $86.84.

Another option is OPEengines.com, which offers free shipping and no tax on orders over $100. The site also includes testimonials from customers who have purchased Kohler fuel parts.

Frequently asked questions