Your lawnmower starts then cuts out after just a few minutes. There are many reasons your lawn mower might stop running. We will explore 10 potential causes for your lawn mower cutting out on you and show you how to fix it.
What Causes A Lawnmower To Randomly Cut Out?
Quick fix: To fix your lawn mower, investigate and identify the root of the issue. Check to see if there is a loose spark plug and inspect the connection for the spark plug to see if it has become disconnected. Clean or replace a dirty air filter. If fuel won’t reach the engine, use a wrench and apply gentle tapping on the side of the carburetor to assist the flow of fuel. Check all areas including a clogged fuel filter or blocked or crimped fuel lines.
1. Full bag shuts off mower
If the lawnmower bag gets too full, the lawnmower will shut off. Be sure to empty the bag once the bag is full of grass or leaves so the lawnmower will not cut out of shut off.
2. Bad fuel
You may be using old fuel or the gas has water in it. This can cause the mower to run for a few seconds and shut off. If this happens with your lawnmower, add a high quality fuel stabilizer and let sit for a few minutes before starting your lawnmower. If a fuel stabilizer does not fix the issue, try draining the fuel from the mower and add new high quality fuel. After priming or choking, try starting a few times to get the newer fuel into the fuel system.
3. Air filter dirty
Lawnmower air filter may be clogged. If the air filter is dirty, take out the air filter and remove any debris. Wash the air filter with soap and water to clean. Once the air filter is clean reinstall it in the mower. Try starting the mower to see if a dirty air filter was the issue.
4. Spark plug problems
The spark plug in the lawnmower may need to be replaced even if it looks to be in good shape. Spark plugs generally last for two years, but a spark plugs lifespan depends on how often you use them. Inspect and change a spark plug when there are any signs that it needs to be changed such as hard starting or rough running. Lawnmower spark plugs are a few dollars and can be found at almost any auto parts store or home improvement store. A spark plug is one of the most common reasons a mower cuts out.
5. Carburetor clogged
Mower carburetors may be clogged with dirt and debris. Carburetors need to be clean and free of gunk to work properly or the engine runs then dies. If clogged or dirty, a carburetor will not let the fuel flow through properly and this causes the mower to stall out or not start at all. When a carb is clogged or not working properly, the lawnmower will sometimes start and run normally for about 30 seconds, then shut off but may start back up right after. At times, you can prolong the running time by putting the choke on. If this happens to your lawnmower, it is a sign of a carburetor problem. The carburetor should be removed, inspected, cleaned, and or replaced if issues are found. If the carb is clogged, clean it, remove it from the lawnmower and let sit in cleaner overnight to remove any debris. NOTE: Dirty air filters can also cause lawnmowers to stall out since the air filter acts as an intake for airflow into the carburetor.
6. Oil issues
The lawnmower engine needs the proper amount of oil to run properly. If the oil gets low, gets water in it, or never gets changed, it can cause issues with the engine and cause it to cut out. Check the lawnmower oil level and age and determine if this could be your issue. Check the lawnmower oil filter is applicable. Change the oil in your lawn mower if you find any issues with the oil quality such as water or if the oil has never been changed.
7. Fuel line/filter clog
A fuel line that is clogged can also cause a lawnmower to cut out. The fuel line carries the gas from the fuel tank and delivers it to the engine. If a clog or blockage is in the fuel line, this results in not enough fuel pressure and will result in the mower turning off or cutting out. The fuel filter may also be blocked or clogged and causing the engine to be starved of fuel. Check both the fuel lines and fuel filter.
8. Engine kill switch
Most lawnmowers has an intermittent engine kill switch that may malfunction. This can cause the mower to shut off after running for a few seconds. The engine kill switch is usually located on the handlebar. When the kill switch malfunctions, you will need to remove and replace it.
9. Exhaust clog
A lawnmower with a clogged exhaust system may cause cut outs. If the opening of the lawnmower muffler is blocked with debris, the engine cannot properly exhaust and the lawnmower will cut out. Remove any debris clogging the exhaust.
10. Compression issues
Poor compression in the cylinder head gasket can cause engine cut outs. A lawnmower with poor compression is due to a leaky cylinder head gasket. Compression problems can cause the lawnmower to cut out when placed under heavy demand such as extra tall grass or large amounts of leaves.
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This is a list of 10 potential causes for your lawnmower to randomly cut out. Lawnmowers are durable machines, but occasionally they can start acting up and cutting out. The quick fixes and solutions will help you to maintain your lawnmower and get it back running as soon as possible.
We can provide tips on what to do if your lawn mower suddenly cuts off or stops running during use. Leave your question below in the comments section and someone can assist you.
Please supply us with the model number of your lawnmower such as “Honda Model #HRN216VKAA – HRN 166-cc 21-in Self-Propelled Gas Push Lawn Mower” and we can find the most probable solution to get your lawnmower running again.
2 thoughts on “10 Issues That Cause A Lawnmower To Randomly Cut Out”
We have Troy-Bilt XP zero turn rider with Kohler twin cylinder engine runs good for two or so hours then starts cutting out and chokes out. We have had 2 different mechanics check it out and no luck. Any ideas ? Model SV7308.
I’ve been trying to figure out why my sister’s Craftsman riding mower shuts off when hot. It has a 19hp B&S 33R877-0002-G1 single cylinder OHV engine. My first thought was a bad ignition coil but I replaced that and the spark plug with no change. I also tried running it with the gas cap off, still no change.
Right now I have the engine cover removed so I can watch the throttle and governor linkages. What I noticed is that after about five minutes of full throttle the throttle linkage starts fluctuating and if allowed to continue it eventually sputters and dies. If I hold the governor linkage steady it continues to run smooth. Could it be a weak or missing spring or is something else causing it to fluctuate?
This is an OHV engine and I also noticed a small oil leak near the valve cover which drips on the muffler and causes some smoke when it burns off. I don’t think it is a bad head gasket but if it was could that be causing the governor and shut-off issues? The engine note doesn’t seem to change once it gets hot unless the throttle linkage is allowed to flutter.