How to Fix a Lawnmower Throttle Cable. Here is how to diagnose and fix it


The lawnmower Throttle cable is responsible for controlling the speed of the engine. If the mower doesn’t respond or the engine dies down when using the throttle, the cable needs to be checked. In most modern push mowers, a throttle cable is connected to the carburetor’s intake valve. When the throttle cable breaks, the intake valve will stay put, and it is hard to start. Over time the cable gets stretched, worn out, and eventually can break. When broken, you can not really use the lawnmower anymore. In all cases, the cable needs to be fixed or replaced.

How to fix a lawnmower throttle cable. Here is how to diagnose and fix it:

The first step is to check the condition of the cable. Is the cable snapped? In that case, it needs to be replaced with a new one. If it is just hard to move, you can use some WD-40 to lubricate the cable. If the Z-tip is broken, replace it with a Z-end created from 7-inch #16 wire.

My throttle cable does not work. What is wrong?

Your lawn mower’s throttle cable controls the throttle of the engine. It’s the part that kickstarts the engine and also commands the speed of your mower’s blades. If the mower doesn’t respond or the engine dies down to the throttle handle’s adjustments, it is a clear sign that something’s wrong with the throttle cable, and you may want to find out what’s wrong. A throttle cable may be very tiny, but it coordinates your mower’s engine parts’ functioning the moment you pull it. Modern lawn mowers have automatic throttle cables.

Before starting with the more detailed procedure to replace or fix the cable, you first need to diagnose the problem. First, check if the cable is broken. In that case, you can pull the cable out of the outer tube. If the cable is broken somewhere in the middle, it is simple. There is no other option than to replace the cable. If the Z-tip is broken, it may seem that the whole cable is broken. But that is not the case. If you pull the cable out of the outer tube, you can see that the whole cable length is still in one piece. If that is the case, probably the Z-tip is broken. That is something we can fix with a new Z-tip.

In case the throttle cable does not work well but is not broken, it can mean that it is just stuck. This is possible if the inner cable starts rusting or dirt has entered the outer tube. The best fix you can try is to use some WD-40 to lubricate the inner cable. Spray it and then try to move the cable a couple of times. If you notice that it works better, you can repeat the same process a couple of times. If it does not work, you should replace the throttle cable.

How does a Lawnmower Throttle Cable Break?

As you use your lawnmower over time, the cable gets stretched or worn out, resulting in breakage. A broken throttle cable is difficult to push, giving you an idea that it’s time to change the throttle cable. When the cable breaks, there won’t be enough power supplied to the mower’s engine, so a broken cable has to be replaced at the earliest.  

When the throttle cable gets worn out, you may order a new cable for your lawnmower model. A throttle cable is quite easy to get. You can order it online or find one at a nearby hardware store.

Guide for Fixing the Z-tip from a Lawnmower Throttle Cable

● Locating the throttle cable on your lawnmower

The throttle cable of a modern lawnmower can be found running from the throttle lever to the carburetor’s intake valve. You may consult your mower’s manual for the most accurate info in this regard for your model.

● Collect the tools you need: 

You will need some measuring tools, a z-bending tool, a new throttle cable, wire cutters, and a needle nose plier to complete this task for the Z-tip replacement.

With the right tools gathered, you may start the Z-tip replacement procedure, which is as follows:

  • Step 1: Get a 7-inch #16 wire size cable.
  • Step 2: Twist the new cable on one end. Twist it enough but make sure not to break it. Make a Z-bend of your cable. It should be the same as the original already installed throttle cable.
  • Step 3: Snip off Z-bend ends of the wire
  • Step 4: Combine the new Z-bend with the old throttle cable. Before combining, make sure to make new and old Z-bends are of the same size. So, if you have a long Z-bend, trim it from one of the ends to make it similar in size to the Z-bend of the old cable.
  • Step 5: Replace the broken Z-tip of your original throttle cable with the Z-tip of the wire using a wire union device or a hammer if you don’t have a union device.

We will now look at the various steps in more detail:

● Step 1: Get a 7-inch #16 wire size cable:

Get a 7-inch #16 wire size cable and bend it in half. We recommend getting an aluminum cable since it will be easier to twist and turn. Flatten the aluminum wire using a pair of needle-nose pliers. If you have any other wire flattener device, use it to press the two bent halves together even more.

● Step 2: Twist one end of the new cable:

In this step, you’ll create two Z-bends, one on each end of the wire. To do this, hold the bottom two inches of the wire to a wire flattener device, or you can use any device that can hold a #16 wire upright so that you can twist the free length of the wire a few times. You may hold the wire using a couple of sturdy needle nose pliers if you don’t have a wire flattener. Twist the wire enough but make sure not to break it. Create a Z-bend on the wire by bending the top of the wire at a 90-degree angle using a pliers pair. Then, take a couple of needle-nose pliers to hold the first 90-degree bend with one as you try to make a second 90-degree angle on the other end using the other pair of pliers. You may copy the Z-bend on the original throttle cable for this step.

● Step 3: Snip off the Z-bend ends of the wire:

Snip of the Z-bends of the aluminum wire.

● Step 4: Combining new and old throttle cables:

The next step is to combine the old throttle cable with the Z-bend of the aluminum wire. Put the original wire above the Z-bend on a table so that both of their Z-tips are parallel. Use a marker to mark the part that you need to cut.

Cut the original cable just right at the tag. For the Z-bend of the aluminum wire, snip 1-2 centimeters extra from the marked point.

● Step 5: Replace the Z-tip of your original throttle cable:

Carefully insert your original throttle cable into one of the holes of a wire union device, then insert your Z-bend aluminum wire into the other hole. Tighten up the device to secure the merger of the two cables.

If you don’t have a wire union device, you can use a hammer or a wire flattener for this step.

With this done, you have successfully replaced the broken Z-bend tip of your original throttle cable.

Lawnmower Throttle Cable Replacement and Adjustment

If you have observed a faulty throttle cable’s signs, the best solution will replace it with a new one. You may need to adjust the new throttle cable based on your mower’s behavior.

Replacing and adjusting the cable involves the following steps:

  • Step 1: Remove the faulty throttle cable.
  • Step 2: Place the new cable on the handle.
  • Step 3: Connect the new cable.
  • Step 4: Adjust the new cable. Check if your mower is always idle or running at high speed with the new cable. Based on that, you will have to stretch or relax the newly installed throttle cable.
  • Step 5: A test drive

● Step 1: Remove the old throttle cable:

Turn off your lawnmower and take off the old throttle cable by removing the cable casing with a pair of needle-nose pliers. Free the throttle cable from the throttle arm by opening the unit and pull and removing the lock screws on the handle. Pull out the freed throttle cable.

● Step 2: Place new cable on the handle: 

Place the new throttle cable on your mower’s handle. Look at the engine’s back for the wire base. Insert the cable through the base and the throttle arm. When installing the new cable on your lawnmower’s handle, you may need to drill new holes if there aren’t any holes already and a bolt to fasten the new cable.

● Step 3: Connect the new cable:

Calculate the size of the cable and give it an extra inch for allowances. The allowance will also make the cable a little loose, allowing the handles to be folded down.

Slip the new cable through the housing and fasten it to the throttle handle. The cable should be tight enough for you to have the throttle down. Tighten the lock screw and reinstall the housing.

● Step 4: Adjust the new cable:

Once the old cable has been replaced, you need to adjust the new throttle cable based on your mower’s behavior. For this purpose, restore the throttle to check if the tension is right. Now turn on the mower. If the mower is running too high in idle status, it means that the cable’s tension is too much, and the cable needs to be loosened.

● Step 5: Test Drive:

Once the replacement and adjustment are made, try your mower and see if all works fine. If everything works fine, it means that the replacement has been done successfully.

Precautions

  • Unplug the spark plug before starting any repair. 
  • Wear such as safety gloves and safety goggles to avoid any injury. 

Final Remarks:

Fixing a throttle cable is not difficult. First, diagnose the problem, and then fix or replace the cable. This blog post will take you through the process. Take precautionary measures and always work in a well-lit environment. Please consult the user manual if you are confused about the location of any of the parts mentioned, or consult a professional.  

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