How To Troubleshoot a Riding Mower That Won’t Go Uphill

Have you ever noticed that your riding mower works just perfectly when you mow on level grass, but as soon as you try to go uphill, it visibly struggles, loses power, or stalls and won’t go uphill? If yes, you must have been eager to find out whether it is possible to troubleshoot such failure and, if possible, how to do so?

First, thoroughly inspect the current state of the gas, carburetor, spark plugs, muffler, and blades. Repair or replace the faulty elements.

Initially, this process might seem a little confusing or complicated. But you can easily fix the problem by simply following all the instructions given below. So, read and learn how to troubleshoot a riding mower won’t go uphill.

What Causes the Problem?

There can be one or multiple reasons to cause your lawn mower trouble going uphill.

A riding mower might struggle or fail to go uphill if the mower is starving for enough gas in the tank or the fuel is badly contaminated.

It can also fail due to problems with the carburetor, fouled spark plug, clogged muffler, or defective blade.

Your lawn mower won’t go uphill if there’s a lot of dirt, debris, and corrosion that can cause the air filter to turn bad.

5 Steps To Troubleshoot A Riding Mower That Won’t Go Uphill: 

Nothing can be more discouraging and annoying than encountering such a situation while you have to stop middle of your task because your mower suddenly not responding and giving you a hard time mowing uphill areas.

However, if you go through available online consumer forums, blogs, and YouTube vlogs, you will find several DIY ideas to fix such issues. Remember, not all of those ideas are reliable. Most of them are not even confirmed by the users, whether those tricks actually worked or not.

That’s why you need an effective and easy-to-do method to troubleshoot when it refuses or fails to go uphill:

Things you will need to troubleshoot the riding mower won’t go uphill:

Look at the checklist of the required tools or materials:

Standard Mechanical Tool BoxStiff Metal Brush
Ratchet SetGarden Hose
Safety Goggles & GlovesVegetable Oil

Step 1- Check the Gas level and condition:

Remember, your riding mower’s gas tank needs to be filled with an adequate amount of gas while going uphill.

Otherwise, the mower will eventually slow down, power will start draining or the mower will stall while you try going up.

Your riding mower might still start with a low gas level, but it will not last much longer and ultimately you will see the failure.

Riding Mower Won't Go Uphill

Also, if the fuel or gas tank of your riding mower is located near the mower’s back, pushing the mower can drive low gas levels to the gas tank’s back and away from the carburetor. So, your mower won’t run much longer in such a condition.

That’s why the first thing you need to do is check the gas level and its condition. If the gasoline seems dirty, contaminated, or old, you should change it with the correct fuel and fully fill the tank before starting the mower.

To learn the easiest way to change the gas or fuel of your mower, watch and follow this video.

If you are not sure how to confirm whether the gas is old or contaminated and not usable, see the below picture to understand the difference between usable gas and unusable one:

Check the Gas level and condition

In case you are wondering about how to choose the right fuel for your riding mower, see this video.

Step 2- Inspect the condition of the Carburetor:

Some riding mower models feature a choke switch for additional fuel supply to the carburetor, and when this choke turns bad or malfunctions, such commotions can arise.

Inspect the condition of the Carburetor

To troubleshoot the choke and repair it, follow each instruction given in the Lawn Mower Choke Repair guideline video.

Inspect the condition of the Carburetor 2

It can also occur if the carburetor is dirty because a defective or faulty carburetor will fail to supply enough fuel vapors to the engine for extra push support required for hill climbing.

So, clean the carburetor by following the instruction given here.

If the carburetor’s condition seems too bad and you need to replace it, follow the Riding Lawn Mower Engine Carburetor replacement instruction thoroughly.

Inspect the condition of the Carburetor 3

Even damaged carburetor seals or gaskets can also interfere in the mower’s operation and cause such trouble.

Step 3- Make sure the spark plugs are not fouled:

Next, you need to check whether the internal spark plugs are working correctly or not and none of the plugs is fouled.

These spark plugs are supposed to fire up approximately 1,000 times a minute when the engine operates by pistons moving upward and igniting fuel vapors.

Make sure the spark plugs are not fouled

To confirm the issue, you need to break into the mower’s internal ignition system and test the spark plug.

Make sure the spark plugs are not fouled 2

For regular servicing or maintenance of your riding mower’s spark plug, follow this DIY technique.

Step 4- Inspect the Muffler:

Such issues can also arise due to a clogged muffler because when the mower gas burns, it needs to exit properly.

Otherwise, it can cause engine seizing trouble, and the muffler is the exit point for the gas.

If the muffler turns blocked due to excess debris or fluids spilling, the engine will eventually malfunction and lose significant power.

Inspect the Muffler

First, locate the muffler near the cylinder head and determine whether the muffler needs to be replaced or cleaned.

Then, take the necessary action accordingly.

Watch this video and follow the DIY technique precisely.

Step 5- Look for Dirty Blades & Clean:

Blades with significant corrosion or interference can cause the riding mower to lose power while going uphill.

Look for Dirty Blades & Clean

First, disconnect the spark plug wire and use a ratchet set to remove it to clean them thoroughly.

Look for Dirty Blades & Clean 2

Use a Garden Hose to spray on the mower underneath and the blades to remove all the grass, dirt, and other debris.

Look for Dirty Blades & Clean 3

Use a stiff metal brush to scrub away the stubborn dried grass.

After that, soak each blade in soapy water for ten to fifteen minutes and rinse them.

Next, coat each blade with vegetable oil or spray them with WD-40®. Then reinstall the blades accordingly.


Undertaking such maintenance can be hazardous. Thus, always remember to read your riding mower’s instructions manual first before operating, servicing, or troubleshooting it.

Watch this video.

Frequently Asked Questions

Why does my riding lawn mower stall while mowing uphill?

If your mower is visibly stalling while you try to mow uphill, can be a sign that your mower is not powerful enough to perform the task at hand. This could be caused by defective spark plugs, faulty ignition coils, a clogged carburetor, or a worn-out transmission.

Why does my riding mower tend to lose power while cutting?

This could be due to a blocked air filter, staled or contaminated gas, plugged fuel filter, excess or insufficient engine oil, clogged carburetor, dirty or damaged spark plug, choked cutting deck, or a dull blade.

How to improve a riding mower overall performance?

Use a clean fuel filter & air filter, change the oil as per schedule, as well as inspect the current state of the spark plugs, blades, tire pressure, and undercarriage. Repair or replace them as required.

Final Verdict

If the riding mower fails to move or go uphill, there must be some parts and systems to troubleshoot. Fortunately, a few adjustments or minor replacements can fix the issue. Now that I have explained all the steps to troubleshoot your riding mower that won’t go uphill, you can easily get your mower back in perfect uphill mowing condition.

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