Why is My Lawn Mower Turning Over But Not Starting?

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Perhaps you could be wondering why is my lawn mower turning over but not starting and it is not very old.

Well, the problem may be due to a few different causes and the good thing is that some require an easy fix…..

Let me take you through these and their possible fixes in a way you will easily understand- and I hope that your mower will be back up again and mowing from these solutions!


Why is my lawn mower turning over but not starting?

Now, the most common causes of the issue are old fuel(or fuel delivery problem), a clogged carb, and possibly spark plug issues.

So you can perform your troubleshooting by trying the following repairs/procedures:


Add fresh gas

The most basic reason why it could be having problems is old gas so you want to be sure you are not starting it with old gas.

So the very first thing you should do is drain old gas and add fresh gas (if you had not) to the tank and then try to start it afterward.

Go on with the next steps if not successful.


Try to start it with starting fluid

The next best step is to attempt to start your lawnmower with spray starting fluid.

john deere riding lawn mower turns over but wont start

Just to be clear, a starter fluid is beneficial when the mower engine isn’t used for a long period and for random cold-starts(due to low temperature).

So try to give your lawn mower a blast of the spray into the carb for 2-3 seconds(you have to remove the air filter cover and the filter before) and see if it will jump to life.

The stuff often works and also provides cylinder lubrication but what is more important to note is that if it starts with starter fluid, you probably have decent compression -and voltage too to the spark plug.

And that leaves a gummed-up carb that needs cleaning.

So let us learn how you can do that:


Clean the carb

Your next step should be cleaning the carb……there’s always a chance you might be having a clogged carburetor(and your mower won’t always start, if that’s the case).

And we are talking about clogged jets (in the carb) due to the engine having sat during the off-season.

Do not also forget that when you tilt your mower for a long time oil tends to go into the carb, clogging the jets.

And the thing is most small engine techies usually recommend that you prioritize cleaning the carb whenever troubleshooting a mower engine that turns over but won’t start.

Here now is how to go about this:riding mower turns over but wont start

  1. Go get a good carb cleaner [the B-12 Chemtool cleans the fuel system great not to mention that it is super inexpensive]
  2. Remove the carburetor.
  3. Submerge the carb in B-12 (pour into the bowl) for a couple of hours to dissolve all debris out of the carb.
  4. Remove it from B-12 and then allow it to dry overnight.
  5. Re-install the carb and start your mower- it could roar back to life.

It’s worth mentioning that you might see a tiny hole if you are able to see into the carburetor..

Now, that small hole is where fuel comes in through, and may be clogged so try to bend either a paper clip or a safety pin and use that to also clean it out.


Alternative cleaning method

You can as well get a good spray carb cleaner(like this) and some needle jet cleaners (here is a good set).

You then ream those clogged jets plus any small passages(with the needle cleaner).

Keep in mind that you’ll need to spray again and then blow out with air and reassemble.

And if your mower has welch plugs, you might need a re-build kit if you’re not able to flush behind them.

Quick Note: If, after several attempts, the mower still doesn’t start, then you likely have a bigger issue…and the main suspect is a bad fuel line (we look at what to do about it next)..


Check the fuel line

The other possibility is a blockage in the fuel line including the line connecting the mower’s fuel pump to valve cover.… You could have a blockage/damage somewhere that you need to remove.

You might even have to replace the entire fuel line (and your fuel pump) to get it to start starting instantly once more.

Besides, it is occasionally good to drain the tank a bit as whatever is running in the gas line can be contaminated with water (for example, if the mower had ethanol fuel, ethanol usually attracts water).


Riding mower turns over but wont start -More potential fixes

Check for Spark – take spark plug out while leaving the wire attached. You then lay it against bare metal surface and crank the engine to see if there’s a spark. Clean/replace the spark if you see no spark.

Also, consider replacing air filters.


A dirty air filter(It could be contaminated either with grass or dirt) does not let enough air into the motor leading to combustion issues so find the air filters and clean/replace them.

Also, check the choke setting…it is, from time to time, the cause.

If not luck yet, blow into the fuel tank too(to pressurize it to an extent)-as the fuel pump could be losing prime.

Oh, and check that all the battery connections are tight and clean.


Why is My Lawn Mower Turning over but Not Starting: Related questions people also ask….

Will low oil cause lawn mower not to start?

The answer is yes- low oil level can sometimes make a lawn mower fail to start (this is typically thanks to the integrated safety circuit cutting engaging- some mowers have a low oil switch that engages)

So you should always check if the oil is at the required level using a dipstick.

why will my lawn mower turn over but not start

Why is my lawn mower turning over but not starting? –Recap

Overall, if your mower won’t start, try draining the fuel and try some fresh gas first.

Then, if that doesn’t help check for a spark- and if it has a spark, clean the carb.

In fact, it is often because of a gummed-up carb so clean it and see if it will crank to life.

Needless to say, if you find yourself still stuck and unable to fix the problem, you can always consult a lawn mower repair expert and have the issue sorted.

Most importantly, regular maintenance is important if you want to avoid future starting problems.



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