Lawn Mower Blows Fuse When Starting – 5 Things To Identify and Fix

You were peacefully mowing your yard, and suddenly, you heard a loud noise, and your mower stopped working! Is this what brought you here today? Don’t worry. You didn’t break the machine; you just blew a fuse!

Now there can be a lot of reasons why it happened, starting from overheating to your mower’s old wiring. But we are focusing on something else right now. We need to get your mower fixed and a half-cut lawn finish.

So keep on reading to understand how you can find the issue with your mower’s fuse and how you can replace it yourself.

Understanding Why Your Lawn Mower Blows a Fuse

There can be several reasons why your lawn mower’s fuse blew, but here are some of the most common ones and how to fix them.

1. Overheating

If your lawn mower’s fuse gets blown quite often, that can mean that you are overusing your mower, causing overheating and therefore blowing the fuse.

Now apart from using it too much, overheating can also result from debris build-up, and grass clippings getting stuck in the airflow of the motor can restrict the engine from cooling down.

To solve that,

• Clean the engine’s cooling fins and remove any dirt and debris build-up.
• Check near the spark plug for dir and build-up and clean that.
• Check the air filter. You may need to replace it if it’s non-functional.
• Check the fuel lines and see if there are any blockages or leaks.
• Check for any damage or corrosion in the fuse box.

2. Circuit Overload

It’s a highly likely reason why most lawn mower fuses blow up. Circuit overload mainly happens when the lawn mower starts drawing too much current than it requires or the circuit itself is overloaded.

It can happen due to a faulty component, such as the motor, the belt, or the spark plug. On the other hand, a circuit can get overloaded if too many items are connected to the same course.

To fix that,

• Check the wiring and see if there is any loose or frayed wiring.
• Check if the circuit breaker is faulty or not and is properly rated.
• The power cords can be the reason for drawing more current, so see if the cables are alright.

3. Faulty Solenoid Starter

If your lean mower is old enough, then the eroded solenoid starter can also be the reason for blowing the fuse of your lawn mower. The starter solenoid provides the electrical power necessary for starting the engine. Therefore if it is defective, it can cause a short circuit and tripped fuse.

To solve that,

• Check if the starter solenoid shows any sign of damage or corrosion.
• The wiring connected to it is secure and in good condition.
• To check the efficiency of the starter solenoid, connect it with a jumper wire and see if it gets activated. If it does not, you need to replace it; if it does, the problem is with something else.

4. Faulty PTO Switch

A faulty PTO switch can also be the reason for your mower’s fuse blowing up. The Power Take-Off Switch connects the mower to the engine, allowing it to start when the blades rotate.

If the switch is damaged, the blades cannot move, resulting in an electrical short that blows the fuse.

To identify that,

• Start by checking the wiring connection for the PTO switch and look for any loose and frayed wires.
• Replace the fuse with one that is the same as the original one.
• Remove the PTO switch and check it individually to ensure it works properly.

5. Damaged Wiring

Faulty or frayed wires can cause your mower’s fuse to blow up. It mostly happens if you have used your mower for quite some time. But it can also occur with a new model if there are any manufacturing defects.

Or you recently repaired your mower, and they have done incorrect wiring or a loose connection there. In that case, it can also lead to a short circuit and, consequently, blow your fuse.

To know if your mower’s wiring is fine,

• For old mowers, check for signs of damage or loose wiring. Broken insulation can also be an issue.
• In the case of a new mower, if all the other components are working well and the wires look fine from the exterior, there can be a possibility that some wires may be broken internally. In that case, it is hard to identify, and it is easier to change the entire wiring.

Troubleshooting and Fixing the Fuse Blowing Issue Cause By Short Circuit

A short circuit is one of the most common reasons for blowing a fuse, especially in riding mowers, so it will be helpful if we elaborate on it in detail for you.

Firstly, to troubleshoot a lawn mower fuse blowing issue, here are things you would need:

• New Fuse
• Ignition switch
• Engine wire harness
• Chassis wire harness
• Wiring diagram of the mower
• A couple of extra fuses
• Multimeter
• Work gloves

The short circuit in a mower often results from a damaged component or hindered current flow. But now that your mower has already had the fuse blown out let’s focus on fixing it rather than looking for its reason.

Start by Finding the Short

Start by taking the blown fuse out of the fuse holder. To find the short, we will be using a multimeter. We will isolate branches of a circuit in the lawn mower’s wiring and then test each part.

We will first disconnect the wires and use the ignition switch for testing. Don’t worry if you think it’s getting very technical! Follow the steps below, and you’d easily detect the short.

• Step 1: Turn off the ignition key to isolate the section you want to check
• Step 2: Adjust your multimeter to measure DC voltage and insert a one-meter probe on one side of the fuse holder and the other on the opposite side.
• Step 3: read the voltage results. If the multimeter shows no voltage, you can skip the section and move on to the next. But if the multimeter reads voltage, there is a short in the red between the fuse holder and the ignition switch. However, it can also mean an issue with the ignition switch.
• Step 4: To check if the ignition switch is working fine, unplug the switch and check the voltage again. If the multimeter shows no voltage while the ignition switch is unplugged, the problem is with the switch.

But if the multimeter still shows voltage even after unplugging the switch, there is a short in the red wire circuit.

Likewise, you’d also need to check the run circuit and the wire harness to check whether they are damaged or not to find the actual cause of the fuse. Keep the wiring diagram handy throughout the process so you can get everything right.

How To Replace The Lawn Mower Fuse?

If you want to avoid diving deep into the issue and getting a quick fix to continue lawn mowing, follow the steps below to replace your lawn mower’s fuse quickly and easily.

• First thing first! Unplug the mower from the power source!
• Remove the outer cover of the mower.
• Find the fuse holder in the wiring harness. If you need to know what that is, take the help of the wiring diagram of your mower.
• Disconnect the wiring harness from the fuse holder.
• Remove the old fuse and install a new one in its place.
• Reconnect the wiring harness to the fuse holder.
• Put back the mower’s outer covering and plug it into a power source to test whether it works.

When to Call a Professional?

Do you still need clarification on whether you can fix your mower’s blown fuse yourself? If you don’t have much experience with electrical devices like mowers, and the problem doesn’t go just by replacing a new fuse, ask the professionals.

FAQs

Conclusion

The fuse of a lawn mower doesn’t blow that often or easily. So if it happens to you regularly, you must check the machine thoroughly for underlying issues. And if everything is good with the mower, you may be making it overwork, leading to overheating and fuse damage.