22 Reasons A Lawnmower Won’t Start After Winter
It’s frustrating, isn’t it?
You put your lawnmower away at the end of the cutting season in perfect working order and just a few short months later it doesn’t show any signs of starting whatsoever.
But how can this be?
Don’t worry it’s a common problem.
I have repaired hundreds of lawnmowers for-profit and have come across nearly every reason a gas lawnmower won’t start.
There are many common reasons a lawnmower won’t start after winter and in this article, I’m going to cover them all and help you get your lawn mower running again no matter what the issue.
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I’m going to also include what to do if your lawnmower doesn’t start at all, what to do if your lawnmower starts then dies instantly and even what to do if your lawnmower starts and cuts out when it gets warmed up.
We’ll start with the simple things and I do suggest you try all these in the order given no matter how simple they may sound.
This is the exact blueprint I use when repairing lawnmowers for profit.
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Let’s Start Simple!
Please don’t ignore the first few tips as 90% of the time this is why a gas lawnmower won’t start after winter.
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Old Fuel
Fuel is referred to as petrol, gas etc. In most cases, fuel (gas) simply does not last as long as it used to.
If I refer to fuel I mean petrol or gas.
Just because you only filled up the lawnmower tank at the end of the cutting season does not mean the gas is new.
Ask yourself how old the fuel is that is in the storage container? Has it been there more than 3 months?
Modern fuel used by cars is designed to be used almost straight away.
Stale fuel is the number one reason a lawnmower won’t start after winter so be absolutely sure that you aren’t trying to start a lawnmower with stale fuel. If in any doubt replace the fuel.
You can do this using an oil/fuel extractor or by simply syphoning the old fuel from the lawnmower. Do not tip the lawnmower over to drain out old fuel as it will cause further starting issues.
Is The Fuel The Wrong Type?
Believe me, I’ve seen it all.
Once I picked up a lawnmower to repair for profit and the whole fuel tank was filled with oil!
On most modern 4 stroke lawnmowers, there is no mixing required. Many people get confused and mix oil and petrol together. This is only necessary on 2 stroke lawnmowers.
Although mixing may not be a major problem with starting up after winter it certainly won’t help.
Fuel Tap
Does you lawnmower have a fuel tap?
Many Honda Lawnmowers have a fuel tap that sits between the petrol tank and the carburettor.
Just because you didn’t turn the fuel tap off doesn’t mean someone else hasnt! Take the time to check it is turned on.
The tap should lie horizontally allowing the fuel to flow to the carburettor when turned on.
I have picked up many “broken” lawnmowers from auction only to find the simple reason they didn’t run was that the fuel tap was turned off.
Does The Carburettor Have Any Fuel
There are two basic types of carburettor. One that looks like it has a bowl at the bottom and one that has a bright red primer bulb on the side.
I’m going to tell you how to see if either type has fuel.
If your carburettor isn’t receiving fuel from the petrol tank there is obviously no way your lawnmower will start.
This is a very simple procedure.
Let’s start with a lawnmower with a primer bulb. (That’s the bright red button you push before you attempt to start the lawnmower)
Take a flathead screwdriver and remove one screw on top of the air filter.
With the air filter removed press the primer bulb and look to see if any fuel is being pumped across towards the engine. If you see fuel being pumped across then your carburettor is capable of starting the lawnmower.
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Bowl Style Carburettor
Take a look at the bottom of the bowl.
You will see a drain plug in the form of a bolt. Undo the bolt slightly and see if any fuel flows out. If it does it obviously means fuel is being supplied to the carburettor properly.
Spark
Now we know the lawnmower is capable of receiving fuel and nothing has bitten through a fuel line or nested during the winter months let’s check for spark.
If a lawnmower has fuel spark and compression 90% of the time it will start.
Remove the spark plug lead and unscrew the spark plug. Re-connect the lead and set the tip of the spark plug against something metal. Ask a friend to pull the starter recoil and visually inspect for spark.
If you see a spark jump across you know you have spark but if it’s difficult to see you can purchase a spark plug tester that lights up when the plug sparks.
If you are unsure replace the spark plug with a good quality NGK plug.
If you don’t have spark there could be a problem with the ignition system and I will cover this later in the article.
You can purchase spark plugs here https://repairlawnmowersforprofit.com/recommended-products/spark-plugs/
Check The Blade
With the spark plug removed tip the lawnmower slightly with the exhaust facing the ground and the carburettor facing up.
Take a look underneath to make sure nothing is obstructing the blade. Often there can be something between the end of the blade and the cutting deck.
If the blades don’t turn when pulling the starter rope, the lawnmower won’t gather enough momentum to start.
Choke
If your lawnmower has a throttle (speed control setting) make sure it is set to choke to start the lawnmower.
If you are unsure where this setting is it’s usually just above the fastest speed setting. This choke should close of a butterfly valve on the carburettor to choke the air and help start your lawnmower.
Check The Lawnmower Choke Setting
If your lawnmower has a throttle and a bowl style carburettor it will likely have a manual choke.
To check this is operating correctly remove the air filter and take a look through the air filter box into the carburettor.
Ask a friend to operate the throttle lever. You will see a gold/silver valve open and close.
When the throttle is set to the choke position the valve should be completely closed. If it isn’t you can adjust the throttle cable by loosening the cable that usually runs below the carburettor and repositioning it.
This is, of course, unlikely to have moved during the winter months when the lawnmower isn’t in use but something may be obstructing the choke if it’s decided to nest in there.
Try and Start The Lawnmower
Now we know that we have fuel to the carburettors, spark and the choke mechanism working correctly you should attempt to start the lawnmower.
You will now have one of three things happen.
- Nothing at all
- Lawnmower starts briefly then dies.
- Lawnmower runs for a minute then dies when it gets hot
Kill Switch And Micro Switch
One thing to check if your lawnmower won’t start after winter is the kill switch or microswitch.
Your lawnmower will have one of these fitted.
Here’s a video showing how to check the kill switch.
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Kill Switch
Most Briggs And Stratton Engines have a kill switch fitted. If it does not disengage the lawnmower will not get a spark and therefore not start.
When you operate the safety lever take a look at the cable that moves. This cable runs to a kill switch. Remove the cover and operate the safety lever on the handle. You should see a definite disconnection of the kill switch when the cable is operated.
If you don’t have a disconnection or anything has obstructed the operation of the kill switch over winter the lawnmower will not start.
On the other hand, if this switch is permanently disconnected the lawnmower will run but it won’t stop!
Microswitch
Many lawnmowers use a microswitch instead of a kill switch. Honda regularly uses a microswitch.
Operate the safety cable and listen for the click of the microswitch. I have picked up lots of lawnmowers to find the only fault was the microswitch wasn’t getting the correct connection from the cable.
Some microswitches are designed to click and some aren’t, so follow the safety cable and ensure the microswitch is being activated correctly.
Here’s a video on how to check the microswitch on a Honda Petrol Lawnmower
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How To Tell If You Have A Fuel Starvation Problem
You may have fuel successfully flowing from the tank to the carburettor but how do you know if the fuel is actually reaching the spark plug?
One way I like to check for fuel starvation is with a can of easy start fluid.
Here’s how to check.
Remove the spark plug and spray some easy start fluid directly into the engine. Quickly replace the spark plug and attempt to start the lawnmower.
If the lawnmower starts and dies after a few seconds you can be sure you have a spark and a fuel starvation problem. I like doing this as it tells me a lawnmower will run once it receives the correct fuel and because it briefly runs I can be sure I have spark.
At this point I would recommend servicing the carburettor, however, there is one quick fix we can try.
Drain The Carburettor Fuel Bowl
If your lawnmower has a bowl-style carburettor it will have a drain plug on the underside. Look for a bolt around 10mm wide.
Take a small tub and place it below the carburettor. Slightly undo the drain plug until fuel starts to appear. This will drain any stale fuel from the carburettor and allow new fresh fuel from the tank to replace it.
I suggest trying this procedure first as it may eliminate the need to fully service the carburettor.
Electric Start
I’m quickly going to state the obvious. If your lawnmower has an electric start make sure the battery isn’t flat and use the starter recoil to start the lawnmower.
Ignition Coil Failure
I have repaired hundreds of lawnmowers with ignition coils and only once has the ignition coil been faulty.
There are other reasons you may not get a spark. Make sure the ignition coil wire isn’t damaged.
You will see the wire if you remove the starter recoil. The wire runs right around the flywheel and often gets damaged when the recoil cover has been incorrectly re-fitted. Look for splits or damage to the wire.
Take a look at the spark plug lead that connects to the spark plug.
When this is connected properly it should snap on. I have seen the inside of the spark plug wire become damaged and not make a good connection with the spark plug. If you have had the lead removed over winter be sure to take a look inside it.
Here’s a video on how to set the Ignition Coil.
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Split Primer Bulb
Primer bulbs often become split during winter months especially if the lawnmower is stored outside or somewhere with no warmth.
Never use aftermarket primer bulbs when replacing as they really don’t last very long.
Take a look at your primer bulb and make sure there are no splits or leaks. I have even seen them with holes in due to being bitten by mice!
Hydrolocked Lawnmower
If your lawnmower feels incredibly difficult or impossible to pull over it could by hydro-locked. Luckily this is an easy repair.
Remove the spark plug and pull the lawnmower over 10 times without the spark plug fitted. This will unlock the lawnmower. Re-fit the spark plug afterwards.
This often happens when a lawnmower has been tipped up whilst in storage.
Governor Springs
Governor springs are fitted to most lawnmowers. If they don’t move freely you will have difficulty starting your lawnmower.
Remove the air filter or look around the carburettor at all the springs and linkages. Make sure that nothing is obstructed and all the springs are able to move back and forth.
Many lawnmowers have governor springs that are exposed to the elements and often parts can become obstructed or even frozen.
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Pull Start Problems After Winter
If your lawnmower seems to have lost all its compression over winter you may have a pull start problem.
Of course, no lawnmower is going to lose compression from being stored but I have experienced using the pull cord only to feel no resistance. This can be mistaken for loss of compression.
What frequently happens after winter is that when pulling the starter rope two wing pawls fail to engage with the engine itself.
They are designed to spring out when the pull cord is activated but often fail to do so after winter.
If this happens then remove the starter recoil and spray with some penetrating fluid. After a few more pulls of the starter rope, the wing pawls will spring to life.
Re-fit the starter recoil and start the lawnmower.
Lawnmower Starts Then Dies
If you have a lawnmower that started up fine after winter but cuts out after a few minutes you need to clean the cooling fins.
Nests tend to appear over the winter months so remove the starter recoil and blow out all the cooling fins until they are completely free of grass or nests.
Most lawnmowers that run fine for a few minutes then cut out usually have an overheating problem. I would fit a new NGK spark plug also as overheating won’t have done it any favours.
White Smoke Problem After Winter
I pick up lots of lawnmower with white smoke problems. This happens when a lawnmower has been tipped up the wrong way or tipped over completely.
If you have had your lawnmower tipped up during the winter months it will smoke when it first restarts. White smoke is quite dramatic at first and many people usually part ways with their lawnmower at this point.
If you leave the lawnmower running for five minutes the white smoke problem will disappear.
If you need to, just run the lawnmower a minute at a time but eventually all the oil that’s been tipped into the wrong places will burn off and the lawnmower will be fine. I’ve done this many times.
Unfortunately, there isn’t a more environmentally friendly way of doing this.
Governor Flap
Remove the starter recoil and take a look for a plastic flap the runs part way around the flywheel. Make sure this part moves freely and is bounced back into position by the governor springs.
When re-fitting the starter recoil and any other covers or guards be sure to use the correct length screws as occasionally I have seen screws be too long and stop the governor flap moving freely.
Fill Up The Tank
Most lawnmowers start more easily with a full tank of fuel. I honestly don’t know why but I can tell you from experience they definitely do.
I can only imagine it’s the sudden replenishment with fresh gas into the tank. It definitely helps though.
I really do hope this article helps you gets your lawnmower up a running after winter.
One final thought is that if a lawnmower won’t start it’s usually an inexpensive repair to get it running again.
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Take a look at this article and you too can start repairing lawnmowers for profit. https://repairlawnmowersforprofit.com/how-to-make-money-selling-lawnmowers-my-complete-guide/
You can find lots more information and start repairing lawnmowers for profit by checking out my online training here https://repairlawnmowersforprofit.com/recommended-products/lawnmower-repair-training-products/
Happy Mowing.