Lawn Mower Won’t Start -Your Troubleshooting Guide

Lawn Mower Won't Start

“I just went to start my mower and it won’t start.” Have you ever said or heard this. Do you want to save time and money? A little preparation will help you do My walk behind lawnmower stopped cold while I was cutting the grass. It appeared to be out of gas, so I filled it. 

The return of warm weather signals lawns to come out of dormancy and spring into action. But if your lawn mower won’t start, you could quickly drown in a knee-high sea of green.

Dan Hale, owner of highly rated Broad Ripple Lawn Equipment in Indianapolis, says most mower problems are the direct result of failure to perform routine lawn mower maintenance at the end of the mowing season.

“People don’t really address the standard maintenance issues that are important to keep a mower running,” he says. “It’s a piece of equipment that nobody wants to own for a job nobody wants to do.”Mowing the grass is one of the rites of summer, but now your mower won’t start. There are many things that can cause a riding mower to refuse to fire up. This is a guide about troubleshooting a riding lawn mower that won’t start.

Mower engine

For those who don’t like getting grease under their fingernails, Hale recommends a professional lawn mower tuneup, which involves replacing the spark plug and air filter, sharpening the mower blades and changing the oil and gasoline.For optimal performance, schedule the tuneup at the end of the season.Then, all it should take is some fresh gasoline in the spring to get it started again.

If you do find yourself with a dead lawn mower and need a professional tune up, expect a wait.The huge influx of needed mower repairs in spring because most people don’t realize their mower won’t start until their grass has already started to grow.

Engine will not start or is hard to start. 

Possible causes:

1.Fuel tank is empty or shut off valve is closed, or fuel cap vent is plugged 
2.There is water in the fuel. 
3.Carburetor is over choked. 
4.Carburetor is improperly adjusted or needs service. 
5.Ignition system or its wiring is defective or ignition switch is off. 
6.Dead man or other cutoff switch is open or defective. 
7.Spark plug is fouled, improperly gapped, or damaged. 
8.Engine compression is poor. 
9.Operator needs to read user manual.

Engine starts easily but dies after a few seconds.

Possible causes:

1.Fuel tank is empty or shut off valve is closed, or fuel line or fuel cap vent is clogged 
2.Carburetor is over choked. 
3.Carburetor is improperly adjusted or needs service.

Engine misses under load.

Possible causes:

1.Spark plug is fouled, improperly gapped, or damaged. 
2.Breaker points are pitted or improperly gapped, breaker arm is sluggish, or condenser is bad. 
3.Carburetor needs adjustment or service. 
4.Fuel line, fuel filter, or fuel tank cap vent is clogged, or fuel shut off valve partially closed. 
5.Valves not adjusted properly or valve springs weak. 
6.Exhaust ports blocked (2 stroke).

Engine idles roughly, unevenly, or surges

Possible causes:

1.Carburetor is dirty.
2.Air leak in carburetor or intake manifold (e.g., bad O-ring, gasket, primer).
3.Carburetor is improperly adjusted or needs service.

If the previous information was of help to you and you would like to view the entire article please click here .By having a basic guide when Lawn Mower Troubleshooting Guide-Engine you may save yourself many hours of anger and disappointment when you find out that it was something as simple as water in the gas that been preventing the mower from starting.

The assumption is that the engine started and ran normally prior to the incident

Now, no matter how many times you yank the starter rope or run the electric starter, it will not start at all, bucks, kicks back, backfires, or fails to develop enough power to keep going on its own.

If the blade struck a solid boulder while the engine was set on ‘high’, more severe damage is possible as even with soft metal keys locking the blade and flywheel to the crankshaft, the inertia of the rotating blade is acting sideways against the crankshaft in addition to suddenly stopping its rotation.

This can result in a bent crankshaft. The end of the crankshaft with the blade adapter could be bent without affecting the bearings or internal parts. This would need to be tested for as well. Not that such an occurrence is that much better – the crankshaft would still have to be replaced but at least the bearings in the crankcase will not be damaged.

If the starter will not turn the crankshaft (assuming you remembered in your haste to engage the safety bar) – it is seized or will only rotate part of a revolution before hitting against something solid inside – then you probably have serious internal damage that will require a complete strip down and replacement of some (expensive) parts. 
lawn mower flywheel

If it turns but much more tightly than you recall (assuming you do have the safety bar engaged!) then the crankshaft may be bent – again very expensive.Repair may not be worth it.However, in most cases, what has happened is that either or both of the blade lock key and/or flywheel key have sheared to protect the crankshaft from serious (and terminal) damage.

If the blade lock key broke, the blade will no longer turn rigidly with the crankshaft and provide the inertia required by many small engines with undersized flywheels.In this case, the engine may try to start but die out with a few “putt-putts” or even kick back on the starter cord. 

(As a side note, attempting to use a lawn mower engine as a replacement on a piece of equipment that doesn’t have something to substitute for the blade’s inertia may not work for this reason.) If the flywheel key broke, the ignition timing will likely be totally wrong and the result may be no ignition, backfiring, kickback, or weak or total loss of power.

To check and diagnose your lawn mower,proceed as follows:

First, pull off the spark plug wire and tie it securely away from the spark plug terminal (several inches minimum) or remove the spark plug entirely so that there is no chance of the engine accidentally starting. Even though it will not start now no matter what you do, the underlying problem could actually be a flooded carburetor or something else which may correct itself while you are working. Never take chances.

Drain the gas or remove the fuel tank. This will prevent gasoline from spilling out the gas cap vent hole or flooding the engine through the carburetor since you will need to tip the mower to get underneath.


Set the mower on its side (carburetor side up)

CAUTION: Immediately check for oil leaks at the oil filler pipe or elsewhere.

The mower can usually be set on its side for a few minutes without harm but if these occur – you will have to work with it tipped less than 45 degrees or so – propped on wood blocks. Or, use this as a good excuse to perform an oil change and drain the oil (even if the engine is cold, most of the oil will drain out – it will just take a little longer). 

Just don’t forget to refill the crankcase with fresh oil once you have completed your work!Using an old rag and/or proper work gloves, grasp the blade and attempt to rotate the blade and crankshaft.

CAUTION, despite your lack of maintenance, the blade may be sharp!.

The blade and crankshaft should rotate together.If there is slippage, the key has broken and will require replacement of just the key or the entire blade adapter plate depending on design. If it appears to be intact, then you can assume the flywheel key has broken.The blade key may be broken as well but it is not likely the reason for your failure to start.You should remove the blade to determine this for sure before restoring the mower to service in any case.

You can possibly avoid removing the flywheel for inspection of the key by unscrewing the sparkplug, rotating the crankshaft so the piston is at TDC, and noting the location of the magnet on the flywheel relative to the magneto coil pole pieces.The magnet should be pretty close to the magneto in that position.If this is not the case or just to be sure, the flywheel will have to come off to inspect and possibly replace the key.

How to start a lawn mower

  • Check the gasoline. Is it the same gas you used last year? If the gas is older than 30 days, empty it from the mower and start fresh.
  • Check the oil. Each mower is different, but you should measure the amount of oil and check color consistency. Change the oil if it appears dark black in color.
  • Check the air filter. Clean or replace your mower’s air filter annually.A new air filter typically costs $3 to $10.
  • Check the spark plug. Your lawn mower won’t start if the spark plug becomes disconnected from the lawn mower. A new spark plug costs around $5.



Eien Find

Single mother

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