42 in. Deck 19.5hp Lawn Tractor

Experienced gardeners share their insights in answering this question :
If the engine run erratically until it has a load on it you may have bad rings or leaky valves.

How to Identify and Fix Common Gardening Problems ?

We provide a variety of viewpoints on how to identify and fix common gardening problems. Our sources include academic articles, blog posts, and personal essays from experienced gardeners :

The most common reason for a surging lawn mower engine is a blockage in the fuel supply, but there are other possibilities: Bad gas. Bad spark plug. Dirty/faulty carburetor.
If your lawnmower`s engine is surging it could be a problem with the carburetor. The carburetor mixes air and fuel to the perfect ratio for combustion. There are passages and nozzles (called jets) that route the fuel through the carburetor. The jets meter the precise amount of fuel that is needed for combustion.
The mower surges when the carburetor sucks air through an unsealed gap in the air intake manifold instead of through the air filter. Dirty carburetor. Clogged fuel jets inside the carburetor commonly cause the lawn mower engine to surge. Clogged jets can`t provide the right mix of air and fuel to the engine.
Check for bent or damaged belt idler brackets, a missing, broken, or worn idler tension spring, and service as needed. If these do not resolve the situation, the problem may be with internal components of the transmission.
Loose, Dirty or Disconnected Spark Plug in Your Lawn Mower: Check it out, clean off debris, re-connect and tighten. Dirty Air Filter: Clean or replace. Fuel Not Reaching the Engine: Tap the side of the carburetor to help the flow of gas. If this doesn`t work, you might need a new fuel filter.
Engine Surging Can Be an Early Warning Sign of Ignition Problems. Engine surging is usually a warning sign that your car or truck is having combustion problems. Since a vehicle`s ignition wires and spark plugs play a major role in proper engine performance, it is likely time to check your engine`s electrical components …
Surging and Lagging

Another good indication that your spark plugs are dirty or worn is if your vehicle experiences surges of speed, resulting in a jerking acceleration. These surges occur because your spark plugs are not igniting the fuel in your engine at the proper rate, resulting in an uneven speed.

Lawn equipment (including lawn mowers, lawn tractors, and even trimmers and blowers) is designed to run at full throttle to give the best performance. Your blade will turn faster at higher throttling, which is essential to proper cutting.
To control engine speed, a mechanical governor uses gears and flyweights inside the crankcase to detect changes in the load and adjusts the throttle accordingly.
What is Bogging? When a dirt bike bogs, it simply means it`s not getting enough fuel and the engine sputters or stalls at full throttle. There are two common types of bogging: lean bog and rich bog, distinguishable by how the bike sounds when you throttle.
Spark Plugs

When a spark plug becomes fouled, the tips become coated with fuel, carbon, oil or dirt. This interference limits the ignition power needed for mowing on level or uphill surfaces. Maintain your spark plugs by changing them every season or regularly removing and cleaning the tips.

How Mechanical Governors Work. A mechanical governor uses flyweights to create a force based off of crankshaft speed which is balanced by the force of the governor spring. The top engine speed is varied by increasing the spring force to run faster or decreasing the force to run slower.
No. It`s not a good idea to defeat the governor on your MTD riding mower.
Engine hunting and surging at idle is usually caused by a fuel delivery, air leak, or governor system problem. Cleaning/overhauling the carburettor, adjustment of the governor, and/or changing the air filer may be required.
If your lawn mower starts, runs briefly, then dies these are the four most common reasons that`s happening: Dirty carburetor / clogged carburetor bowl. Old gasoline that has gone bad. Dirty or defective spark plugs.
If your lawn mower starts, runs briefly, then dies these are the four most common reasons that`s happening: Dirty carburetor / clogged carburetor bowl. Old gasoline that has gone bad. Dirty or defective spark plugs.
If your lawn mower starts, runs for a while, then dies, check the ignition coil, gas cap, and spark plug. One or more of these parts could be causing your problem. Follow our repair and symptom guide to help you fix this.
The problem may involve an annoying change (up/down) of engine speed while cruising at a steady pace, a low drop (or even cut-out) at idle or when approaching a stop, a wild high engine speed of several thousand rpm followed by a drop to near zero, etc.
The problem may involve an annoying change (up/down) of engine speed while cruising at a steady pace, a low drop (or even cut-out) at idle or when approaching a stop, a wild high engine speed of several thousand rpm followed by a drop to near zero, etc.

Discover Relevant Questions and Answers for Your Specific Issue

the most relevant questions and answers related to your specific issue

Lawn mower motor runs good, the drive wheels run good but the blade won’t stay enguaged. Thanks
ANSWER : Check your cable that controls the blade engagement.

Lawn mower will start and run for 5 seconds and shut down
ANSWER : Will it stay running with your choke on? if so then clean your carb. if not then look for a blockage from tank to carb. ie fuel shut off, deteriorated fuel line. plugged filter etc

I have a Poulan push mower that after mowing in a ditch started making a loud noise and running rough. It almost sounded as if metal was hitting metal. The mower was vibrating more than normal. I checked under the mower and nothing is hitting. After a few times of stopping the mower engine because it sound as if it is going to die down the mower will not start now. The shaft does not appear bent and the blade appears ok. The mower has oil, a good spark plug and a clean air filter. It was running fine until that moment. I did not see anything that I hit but it is possible I hit something in the ditch like a pine cone or branch. What could the problem be and how would I go about fixing it?
ANSWER : If you are sure the oil level is correct then it sounds like it’s about to die, unfortunately. A pine cone shouldn’t cause any damage, but a large branch may do so. Was it smoking before you shut it down? The vibration could be caused from a bent blade. It could also be caused from a part breaking in the motor. I wish I could have given you better news!

Good Luck,

Jim

Carb problems wont stay running unless i unplug and plug in the anti diesel switch the plug on the fuel bowl
ANSWER : Check and see if all your carb jets or clean sound like some dirt got into one

I can’t start it because the pull cord is stuck and it happened after I installed a new blade.
ANSWER : If the recoil assembly has three screws holding it in place, remove them, lift the recoil assembly off and see if it works off the mower. If it does, reassemble.
Gary

Lawn mower cranck but wont start…
ANSWER : Since you already checked for spark and air I would drain all the fuel out of it and check that fuel for water. Over time some lawn mowers end up with contaminated fuel. You can see the water sitting on the bottom of the fuel if you let it stand for a bit in a small plastic bowl.

Be sure to empty and dry out you fuel can as well. Especially if the mower stopped running right after a refuel. Which is a good sign your gas can is contaminated too.

MTD Yard Machines 22” mower, pull cord won’t extend
ANSWER : Found out that after unboxing the mower you have to pull the handle out 8 inches to a second set of holes for the T-bolts near the frame. Up under the frame of the mower the handles go down and block the blade from turning.

I have trouble starting a toro walk behind mower
ANSWER : All, I thought my carb was shot, so I replaced it. Still, start but no run (and had to use starting fluid). THEN!!! I noticed the spring to the “rev limiter” (just below and towards rear of carb) was not “tight”. The stupid bracket that holds the end of that spring had been bent down ~1/16″ and that caused all this heartache. CHECK YOUR REV LIMITER!!!