How to Bench Test a Lawn Mower Starter?

Sliver Lawn mower - man using lawnmower mowing lawn

It is the start of the mowing season, and it’s time to cut the lawn, so you reach for your lawnmower and try to turn it on, but there you go, nothing happens. This could mean that there are a few problems with the electrical starting system on your lawnmower. Most of the usual electrical problems are normally due to a faulty battery or corroded or loose wires.

Some of these problems are even due to electrical connectors and damaged electrical components like the starter solenoid. Some of the major parts that fail on electrical starter motors include the springs, the magnets, and brushes that provide the electromagnetic turning force of the engine starter.

How to Know if Your Lawnmower Starter Is Faulty?

Before you replace your lawnmower starter, you need to first be sure that the current one is damaged. There are a few components to examine before you conclude that the starter is faulty.

Battery

The first component that should be checked when you want to identify engine starter problems is the battery because engine starter problems cannot be diagnosed without sufficient electricity. If you want the starting, charging and electrical system of your lawnmower to be in optimal shape, then you need to make sure that the battery is properly charged.

Ensure that you charge the battery of your lawnmower fully using a 6 amp battery charger before you carry out any diagnostic test on the starter motor. Generally, lawnmower batteries are 12-volt batteries, and they normally have a voltmeter reading of 12.7 to 12.9 volts after a full charging session. So, if you fully charge the battery of your lawnmower and you get a voltmeter reading that is below 12.4 volts, then you should consider replacing the battery.

Electrical Connections and Wiring

The mechanical connections that involve a metal connector being soldered to a wire that is bolted to a part of an electrical component of the lawnmower such as the engine starter motor, starter solenoid or switch are electrical connections and wiring. If the electrical connectors and wiring are loose, corroded or broken, then the flow of electricity will be interrupted, and then a reduced voltage will be supplied to the electrical components, which will result in improper operation. Ensure that you clean the electrical connectors with a wire brush.

Starter Solenoid

When the key is turned, voltage from the battery starts the starter solenoid which is basically a remotely mounted switch that starts the motor. You can examine the starter solenoid by connecting a jumper wire from one large lug to the other. The battery cable is attached to one large lug while the engine starter cable is attached to the other. If the engine starter motor turns over, then the starter solenoid is faulty and needs to be replaced.

Starter Motor

This component is an electrical motor that is attached to the engine crankcase. The starter starts the lawnmower engine by turning the engine flywheel teeth with the teeth on the starter motor plunger.

Once you have checked all the other components and they are in perfect working condition, then the problem is definitely with the starter. It is likely that the brushes, spring, and magnets that contact the wire winding inside the motor are dirty or worn down.

Symptoms of a Bad Lawnmower Starter

  • Once the connection between the battery and the solenoid becomes loose, and you hear only a clicking sound, then the starter is bad.
  • When a whirring sound made by the lawnmower when you try to start it up is not followed up by the rumble of the engine, then it means there is a problem with the starter.

Bench Testing a Lawnmower Starter

If you need to replace the starter on your lawnmower, then check out the new starter motor that can fit a Briggs and Stratton engine.

After you have gotten a new lawnmower starter and installed it, it is now time to test it. The starter gets its electricity from the onboard battery, so make sure that the battery is fully charged, and all connections are tight. The circuit starts from the ignition key, and just as it is with starting a car when you turn the key, the circuit is completed through the solenoid that acts as an electrical connector sending power to the starter which causes it to spin the flywheel, and then finally starts the engine. In order to test your starter, you would need to bypass the ignition circuitry.

  • First, ensure that you take safety measures before carrying out any of these tests. Wear a pair of gloves and goggles
  • You need to locate both the battery and starter, which is located under the hood of the lawnmower. Raise the hood to uncover them.
  • Next, locate the electrical posts; this is where the wires are attached to both the battery and the starter. You should see two wires; the red wire represents “hot” while the black wire represents “ground.”
  • Then proceed to brush off the posts with a stiff-bristled brush, making sure that you get all the dirt and debris off. This is to make sure that you establish a solid connection.
  • This is the step where the rubber gloves come in hand, connect one end of the black cable from the jumper to the black wire or negative terminal of the battery. Then attach the other end to any metal part of the lawnmower.
  • Next, attach one end of the red cable to the red wire or positive terminal of the battery. Then connect the other end of the red cable to the positive side of the starter. If there is no problem with the starter, then it will turn over. But if it is a faulty starter, then it will not turn over, consider replacing it immediately.

Summary

A starter problem is not so hard to identify; you can do it yourself without having to call a technician. You can now check where the problem is coming from and if your starter needs to be replaced.

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