Pull the string or turn the key and nothing... the lawn mower won't turn over? This seems like a disaster. Especially if it's the middle of summer, grass has grown thick and the weeds seem to sprout up in the yard right before your eyes. Before you go cutting the grass with pruning shears check out these possible reasons for why the lawn mower wont start. 


Push or Riding Lawn Mower Won't Turn Over 

There could be several reasons why your push mower or riding lawn mower won't start. Here are some of the most common reasons that may be causing it to not turn over.

Is there gas? Is the gas old? Gas can go stale losing its potency and making it impossible to start the mower. If this is the cause it will need to be emptied and replaced and the carburetor needs to be cleaned. 

Many riding lawn mowers come with built in safety features that can prevent the engine from revving up. One such feature requires that the driver be seated at start up so if you are trying to start cold before hopping on this could explain the lack of response.  Next is a feature that requires the clutch/brake to be completely depressed when the key is turned otherwise no signal is sent preventing it from cranking. Last but not least is the deck - some models will not turn over if the deck is engaged or set to on. 

Another potential reason  that the mower may not be starting is another safety measure that some lawn tractors have built in which requires the rider to remain seated while the mower deck is in the ON position. Ensure that you remain seated while the mower deck is switched to the ON position, if your riding lawn mower has this safety feature built in.  

If the problem lies in the safety circuits you will have to find out where the issue is stemming from by isolating them one at a time until you can identify the cause and replace the defective equipment, wires or switch. 

Check the cables and wiring for the ignition. Things happen and sometimes wires and cables can work themselves loose or be jarred out of place. Ensure everything is firmly connected. 

Check your battery: A volt meter can be purchased to check the charge on the existing battery. Many a time this is where the problem is stemming but short of changing it out the only way to really know is to test it and ensure the battery has the proper charge needed to start. 

Check your spark plugs. Sometimes the wires can loosen resulting in an inability to start the mower. You may also need to replace the plugs.  Attempt to start the mower a few times then check to make sure the carburetor is actually pumping fuel, this can be found by checking the tip of the spark plug for wetness (fuel) which indicates the carburetor should be working properly and the issue is elsewhere. 

Is there oil and is it good? A quick check of your lawn mowers oil can show if this is the cause of your difficulty in starting or keeping your lawn mower running. Oil will typically appear brownish in color when checked if your oil looks black that may be part of your problem. If there is no oil and there should be check for oil leaks, this can be indicative of a more serious problem. 

Are the filters clogged? Wet or dirty filters can prevent the lawn mower from starting or turning over. Double check and replace if necessary.

Are the vacuum lines intact and tight? Cracks can occur due to the excessive heat put off by the engine this causing inadequate air and fuel flow. If the hose appears damaged - replacing it may be the answer. 


More Serious Causes of why a Lawn Mower Wont Turn Over

The above causes are the most common things lawn tractor and walk behind mower owners come across however other more serious issues may be at hand. If you have tried and checked the above to no avail other more serious causes may include (but are not limited to): faulty or dirty carburetor, which you may be able to disassemble and clean or may need full replacement; fuel pump, clogged gas lines, water in the piston chamber or the engine may simply be blown. 

Most of these issues that will make it so the lawn mower won't turn over can be eliminated by simply replacing the defective part if it can first be identified. 


Note: If your lawn mower is under warranty from the retailer or manufacturer attempting to repair it yourself may make your warranty null. If it is covered under a warranty- take it in and let the professionals figure it out.