Toro Lawn Mower Repair – Carburetor Replacement

The Story:

When we purchased our house nearly two years ago we were faced with a decision that every homeowner has, to mow our own lawn or hire a lawn guy. Clearly, I’m not the type to hire something out if I can do it myself. And quite frankly mowing one’s own lawn is an enjoyable and therapeutic exercise. The key word there being exercise. Our lawn is not huge, but at a quarter acre it’s not tiny either. Plus, as a corner house, we have relatively large swales. All in all, it takes me a good three to four hours to get it all nice and tidy, assuming, of course, my equipment wants to cooperate.

As luck would have it while we were in the process of purchasing the house, my wife’s Aunt was moving out of her’s. Given that she was downsizing into a townhouse she hooked us up with a fairly new Toro Recycler lawnmower (Toro Recycler (22″) 190cc Personal Pace Lawn Mower w/ Blade Override – 20333) and a Ryobi handheld gas trimmer. I’ll write about the Ryobi in a separate post as that one has been a bit of a problem child. The Toro though is wonderful. The recycler feature works incredibly well at mulching up your clipping and dispersing it across the lawn. I prefer this option to that of picking up the clipping as 1) it’s easier and 2) I’m naturally adding a layer of compost to the lawn. The other feature which makes the Toro so great is the front wheel drive. At first I thought the idea of having the two front wheels help pull the mower forward was a bit gimmicky, but it truly works wonders. Once you get a nice rhythm going you barely have to touch the mower at all, just squeeze down on the handles and hold on as she plows through your grass.

Of course, I wouldn’t be writing this article if the Toro didn’t have a couple of drawbacks. That drawback though is simply maintenance. Once I brought the mower home she ran great her first time out. A little put-put if anything, but generally speaking, the engine was smooth. Unfortunately the second time out she wouldn’t start. You’d crank her over and she give you a couple of turns but ultimately dies. I decided then to give her a general once over.

The engines on Toro mowers are one of several Briggs & Stratton models. These engines are relatively quiet, efficient and powerful 4-stroke power plants. My model has a single side draft carburetor with no throttle. The fact that the carburetor has no throttle is what I found most interesting. The lever on the handlebar of the motor is not controlling the speed of the engine. Instead, it is releasing a friction stop. As such, when you press the lever the engine is free to run as it should, and when you release the lever it will bring the engine to a halt. What determines the engine’s rpm then? Well, first you have a heat actuated choke, which will open up once the engine reaches operating temperature. Otherwise, the carburetor is basically running wide open. Air is restricted given the shape and opening on the sealed air filter housing, while fuel is delivered through a siphon hole. The size of the siphon hole only allows a set amount of fuel to enter at a time. Once you combine these three features you have an engine that will run at the same rpm all the time, with no external adjustments needed. Quite ingenious.

The setup does leave you with a couple of shortcomings. First, you must maintain your air filter clean (Toro Recycler with Briggs & Stratton Engine Tune-Up Kit). And secondly, you must maintain the siphon hole on the carburetor clean. After analyzing the setup I decided to install a new filter, clean & ultimately replace the carburetor, and install a new spark plug for good measure. The whole process can be accomplished with a simple set of hand tools and shouldn’t take more than an hour.

The Fix:

To remove the air filter you have to remove the top screw holding the housing in place. After loosening the screw the lid to the housing will swivel out and you can pull her up and loose. From there you can just pull out the filter and install a new one. If you’re only removing the filter try and clean the air filter housing as much as possible.

With the filter out of the way, I kept going deeper to remove the carburetor. You’ll have to remove the remainder of the air filter housing, which is held on with three screws. With those removed, you can pull out the air filter housing to reveal the carburetor behind it. The carburetor itself will be held on with two bolts, but before you remove those you’ll need to pull off the fuel line. In order to avoid spilling fuel all over the place, your best bet is to have a stop ready to plug the gas line. You can either pinch the gas line, or plug it. I like to use a wine stopper and just shove it into the hose. With the gas line detached you can now unbolt the carburetor and remove. Take care to unclip the choke lever as it is attached to the top of the carburetor.

Originally I planned on purchasing a rebuild kit for the carburetor, but after checking Amazon, a new carburetor was only $3 more than the rebuild kit… $3! So I purchased a new carburetor (NEW TECUMSEH CARBURETOR 20016 20017 20018 6.75 HP TORO LAWNMOWERS RECYCLER). So, with the old carburetor removed I cleaned up the mounting flange on the engine and installed the new carburetor. Installation is simply the reverse of the removal process. Make sure to use the new gaskets provided for each of the mounting points (carburetor to engine & air filter housing to carburetor).

With all that sorted I went ahead and replaced the spark plug and got to mowing the lawn. As expected she ran great. The mower sounded smooth and powerful with zero hesitation. For the next two months she continued to work flawlessly, and then one day we were back to not starting.

Knowing that everything was basically new, I was a little perplexed as to what the problem could be. I went ahead and took everything apart, cleaned it and put it back together, but still she wouldn’t run. After rummaging around the internet a bit I found a source that showed the issue. Within the carburetor there is a metering needle which controls the amount of fuel that flows through the siphon hole. Since we are dealing with such a small amount of fuel with this engine, the needle is rather small, and as such can be easily clogged.

Luckily, cleaning the needle is very easy, and can even be accomplished with the carburetor still on the mower. The lower portion of the carburetor is comprised of the fuel bowl. Right in the center of the fuel bowl, you’ll notice a brass colored bolt. The metering needle is actually incorporated into this bolt. Cleaning it is a simple as removing the bolt and spraying the tip down with some carburetor cleaner, which is exactly what I did. I reinstalled the needle/bolt combo and sure enough, she fired right up. The needle didn’t even look dirty or clogged, but it’s such a small amount of fuel that almost any microscopic particle can clog the system. 

The Result:

The Toro Recycler Lawnmower is a great piece of machinery. The hardest part of this was simply figuring out what exactly was wrong. Armed with the knowledge that the carburetor will, in fact, get clogged, I’ve simply continued to clean it out every few months when she starts to hesitate. It takes less than 5-minutes and gives you a smooth mowing experience. If you’re mowing your own lawn the least you can do is take a few minutes to make sure your machinery is up to snuff. It’ll let you do a better job and make the experience a whole lot more rewarding.

Useful Parts & Tools to Help you with this DIY Project: