Replacing Fuel Solenoid In Takeuchi: Step-By-Step Guide

If you're experiencing issues with your Takeuchi vehicle, you may need to replace the fuel solenoid. This component is responsible for controlling the flow of fuel to the engine, and a faulty solenoid can cause a range of problems, from difficulty starting the engine to decreased fuel efficiency. While replacing the fuel solenoid may seem like a daunting task, it is a process that can be completed with the right tools and knowledge. Online forums and video tutorials can provide step-by-step guides and tips for this procedure, ensuring you're well-equipped to tackle the job. Additionally, there are aftermarket fuel solenoids available for purchase that can serve as replacements for your original equipment.

How to access the fuel solenoid

To access the fuel solenoid on a Takeuchi TL 140, you will need to raise the cab. The solenoid is located on the left side of the engine if you are under the cab and looking towards the rear of the machine.

There are two bolts holding the solenoid to the bracket, which can be removed with a 10mm socket. There is also a linkage rod going from the shutoff solenoid to the shut-off lever on the pump, with tiny E-clips that can be tricky to remove and reinstall. It is recommended to have the machine on blocks and drop the bottom pan under the engine for more access and to catch any dropped parts.

Additionally, removing the belly pan panel will grant access to the solenoid from underneath the vehicle.

Removing the old solenoid

To remove the old solenoid, you will need to locate it first. On a Takeuchi TB 175 Excavator, the fuel shut-off solenoid is located on the left side of the engine if you are standing under the cab and looking towards the rear of the machine.

Once you have located the solenoid, you can begin the removal process. The first step is to disconnect the solenoid from the S/O shaft. Pull the SOL shaft until it bottoms out in the case. Now, pull the S/O shaft into the OFF position and check that the holes line up. If they do not, you will need to adjust the shaft by loosening the jam nuts and turning it until the holes are aligned.

Next, remove the linkage rod that connects the shut-off solenoid to the shut-off lever on the pump. This rod has tiny E-clips that can be tricky to remove and reinstall, so it is recommended to have some extra E-clips on hand in case they get damaged or lost during the process.

With the linkage rod removed, you can now detach the solenoid from its mounting bracket. There are typically two bolts holding the solenoid in place, which can be removed using a 10mm socket.

Finally, carefully lift the old solenoid out of the engine compartment and set it aside. Be cautious, as the solenoid may still contain some fuel or oil, which could leak out during this process.

At this point, the old solenoid has been successfully removed, and you can now proceed to install the new solenoid.

Installing a new solenoid

To install a new fuel solenoid on a Takeuchi, you will need to follow these steps:

Firstly, locate the fuel solenoid. On a Takeuchi TL 140, it is on the left side of the engine, underneath the cab. There should be two bolts holding the solenoid to the bracket, which you can remove with a 10mm socket. There may also be a linkage rod going from the shut-off solenoid to the shut-off lever on the pump, which you will need to remove. This can be tricky, as it has tiny E-clips which can be difficult to detach and reattach.

Once you have removed the old solenoid, you can install the new one. Ensure that the new solenoid is the correct fit for your machine by checking the serial number. The parts book for Takeuchi TL 140 lists two different solenoids, which are serial number specific.

When installing the new solenoid, pay attention to the wiring. There should be three wires: red, black, and white. The black wire is the ground, the red is constant 12 volts, and the white is only momentary 12 volts for the pull. Ensure that the white wire does not have constant 12 volts, or the solenoid will burn up within minutes.

Finally, you will need to adjust the new solenoid. If it has a rubber boot and two jam nuts on the shaft, you will need to adjust it to make sure the plunger can bottom out in the case. Loosen the jam nuts and turn the shaft to meet the shut-off lever holes. Check and re-check your adjustment before testing the machine.

If you are installing a new solenoid because the old one was burning up, there may be another issue causing this. Ensure that the linkage allows the plunger to bottom out and open the internal switch for the pull winding. If not, the solenoid will generate a lot of heat and burn up quickly.

Adjusting the linkage

When adjusting the linkage of a fuel solenoid on a Takeuchi machine, it is important to ensure that the solenoid plunger can bottom out completely in the case. This may require disconnecting the solenoid from the shaft and pulling the shaft until it bottoms out, and then adjusting the shaft to meet the s/o lever holes by loosening the jam nuts.

To do this, first pull the SOL shaft until it bottoms in the case. Then, pull the s/o shaft to the OFF position and check if the holes line up. If they do not, adjust by loosening the jam nuts and turning the shaft. It is important to ensure that the plunger has fully bottomed out, as it may look like it has to the untrained eye, but it may not be fully bottomed.

Additionally, when adjusting the linkage, it is important to allow the solenoid to bottom out and to fully open the bellcrank, as this allows for full throttle. The length of the solenoid plunger shaft should be adjusted so that the bellcrank is fully open when the solenoid is bottomed out. This can be done by putting key power to the solenoid, pulling it against its spring so it bottoms and holds, and then adjusting the rod in the plunger until the bellcrank is fully open.

Furthermore, the fuel shutdown solenoid linkage adjustment should be checked to ensure that the governor section of the pump can control the fuel rack effectively. The shutdown linkage (internal) can sometimes interfere with the throttle linkage (internal), preventing the throttle from opening fully. To check this, remove the shutoff solenoid and hold the bellcrank at its full open position, and then operate the throttle to see if it feels normal. If the throttle feels normal when the solenoid is removed, then the internal linkage was likely interfering.

Testing the new solenoid

Step 1: Safety First

Before beginning any testing procedures, it is crucial to prioritize your safety and the safety of those around you. Ensure the engine of your construction machinery is turned off, and disconnect both the power and fuel supply to avoid any accidental startups or fuel leaks.

Step 2: Identify the Solenoid Wires

Fuel solenoids typically have three wires with distinct colors: red, black, and white. Confirm that you have correctly identified each wire by color before proceeding with the testing process.

Step 3: Prepare the Testing Equipment

You will need a multimeter or a test lamp to test the solenoid. Connect the positive terminal of your chosen testing device to the red wire and the negative terminal to the black wire.

Step 4: Test the Suction Function

With the test equipment connected, you should hear the solenoid valve sucking closed, and the tester should indicate that current is passing through it. This confirms that the solenoid valve is functioning correctly and can close when it receives the appropriate signal.

Step 5: Test the Release Function

Now, disconnect the negative connection from the test device and connect it to the white wire. During this step, you should not hear any sound of the fuel solenoid shut-off suctioning, and the tester should not show any current passing through it. This indicates that the solenoid can release properly when triggered.

Step 6: Verify Test Results

By following the above steps, you have tested the essential functions of the fuel solenoid. If the solenoid engages and releases as expected when receiving signals, then it is in good working condition. However, if you observe any abnormalities, such as a malfunction in either the engage or release function, it may be an indication that the solenoid is faulty and requires repair or replacement.

Additional Troubleshooting:

• Check Power and Wire Connections: Before concluding that the solenoid is defective, ensure that the power connection to the solenoid is secure and that there are no loose or broken wires. If you find any issues, reconnect or replace the damaged wires.
• Inspect the Relay and Control Unit: If the solenoid tests fine but the engine still won't start or stop, the issue may lie with the control unit or relay. Inspect the relay for good connections and check for any damage or burns. Also, ensure that the control unit is sending the correct signals without any errors or interference.
• Examine the Fuel Supply System: If the problem persists, move on to checking the fuel supply system. Assess the status of the fuel pump and high-pressure fuel injector to ensure that fuel can flow properly. Additionally, check if the fuel filter is clogged, which could result in insufficient fuel supply.

Remember to consult a professional mechanic or a trusted heavy equipment forum if you have any doubts or concerns during the testing process.

Frequently asked questions