Lawn Mower Won’t Start When Hot – What to do

It doesn’t matter if you have one of the highest-rated lawn mowers, such as Briggs and Stratton. Or your mower is a few years old.

Hot engine starting problems can fall on any gardener at any time. You see this most of the time, after mowing for a while, and you stop to fuel up or empty the bag of cuttings.

Regardless of what you try and check, like your oil level, air filter, plug wire, and such, it just won’t start until it’s cold down a little.

Large red lawn mower on the grass

Here, you can learn all you need to know, and ultimately by the end, you’ll know why my lawn mower will not start.

Why Lawn Mower Will Not Start When Hot?

Apart from a failing ignition coil, you can find many issues you need to check. Your mower can also have faulty plugs and plug cables from an engine overheating up to a broken carburetor.

Depending on the surroundings, you could even have a vapor barrier or solenoid coil that is damp or defective.

You will find a list of things to check, no matter how simple they appear. There are many things you need to check, and here are the key areas that often cause these mower starting issues when it’s hot.

Engines Overheating

With all types of motor engines, you will find this problem common. Sometimes engines run good when cold and possibly start again once or twice before you get going. However, once you run for a while, then you run into these problems.

Although your lawnmower has a small engine, while in use, it produces an immense amount of heat, although it has passive cooling fins to disperse heat, you can find grass clippings or debris clogging the fins as you mow the lawn.

Because sufficient heat can’t be gotten rid of from clogged cooling fins, your engine gets hot when running and ultimately stops. Before the engine cools, your engine won’t restart. The plastic covers can also collect dirt and debris and lead to a shutdown of your engine.

Wait until your mower engine is cool; check and clean the plastic housing and the cooling fins on your motor to fix the issue here. (Read How to Sharpen Lawnmower Blades)

Oil Levels to High or Too Low

Some mower engines won’t start when they have low or high oil levels. If the levels are extremely low or overfilled, it won’t let your engine start. Also, while checking this, check the gasoline; you never know when it will run out.

These features are there to protect your engine, such as in some Briggs & Stratton engines. Make sure always to check your oil levels when checking your fuel.

Spark Plug Issues

You can find many spark plug varieties, they come with different heat ranges, sparking gap, and the length. You can find issues such as hot start failures when putting the wrong type of spark plug into your mower.

Make sure to check the spark plug model number or plug code you require. You will need to check you have a spark from the plug before replacing it. If you get a good spark, then the issue maybe something else.

A poor spark can be a sign of a worn plug; the gap is too large or an issue with the plug wire. The plug wire will lead back up toward the flywheel and ignition coil.

The flywheel makes contact each time it goes round to create a spark. You can also have a large gap here, as in your plug. You may need to replace the flywheel or the coil as often they are not adjustable.

The coil would cause the bigger problem of the two as the coil is often a sealed unit, and there is no repair possible.

It may be wise to purchase two plugs when you know you have the same model when you need a new spark plug. (Find the Best Electric Lawn Mower)

Air Leaks

If you never tightened bolts that hold engine components together and the motor to the frame. The bolts will be loose. This would cause your mower engine to shut off.

Small red lawn mower hidden by long grass

Loose bolts would cause air leaks, which cause the engine to suck in excess air. Check for any loose bolts after your maintenance to fix the problem.

Compression Issues

You can spot these issues right away. If your mower starter rope moves easier, it is an indication you have lost compression and may have a large valve clearance. The compression issue is common for Briggs and Stratton mowers.

Sticking Choke

The choke is a part of your carburetor and is used to feed enough fuel to your engine on the first ignition. If your choke sticks on in the carb, it will cause your properly running engine to get flooded without enough air.

Replace your air filter and check inside the carb to see if the choke is sticking and causing the problem. Using your choke too much and your engine starts to burn more fuel, and then it can’t run without it.

Alternative Starting Issues

Besides these reasons here, there are a few others you can find. However, these aren’t as common. You can find the alcohol in the oil causes problems because it has a low boiling point. You can correct this with a shim (non-metallic) between your engine and your carb.

Simple issues can be something, such as the wrong fuel mixture. Your engine may also be running lean, which means it lacks fuel or there is too much air getting in. Turn the fuel mixture up a little.

You can also cause issues with the wrong fuel, where some engine manufacturers could recommend regular gas or other Ethanol levels. Some burn hot and will void a warranty.

Many gardeners like to do with their mowers to turn it on its side as they check the blade. Having your mower on this level can cause fuel to run into your engine, fill the one cylinder, and flood it as the choke problem will. (Find out the best time to buy a lawn mower)

You will never get your engine to restart when it is flooded with gas. You may think this is a problem and you may need a small repair.

There is no problem, and it’s because the gas would run past the valve while you are checking underneath. If you would need to do this, turn off the small fuel tap as this would stop the gas flowing past the shutoff valve. Stand it up and let the fuel run out until it starts again.

Lawn Mower Won't Start When Hot - What to do

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