Small Engine Tools
I’m always suspicious when a job goes smoothly, in fact, I prefer a mower to put up a bit of a struggle. But when it does go smoothly, it’s usually because you’ve got the right tool for the right job.This page is dedicated to those tools.
fuelling system tools
A fuelling system fault, hands down is the most common fault a lawnmower will have. The reasons are simple, carburettors are small and block up with crap easily, check out this post “Lawn mower starts then dies”.
The second reason, people (including me) forget to use a fuel stabiliser in the gas tank over the winter (Keeps gas fresh). Check out this post “How to winterise your mower”.
Cleaning the fuelling system in most cases fixes the problem, Check this post out, “Carburettor cleaning”, but sometimes you’ll need to bite the bullet and fit a new carburettor.
Anyway here’s a list of the tools you’ll find really helpful if your troubleshooting your fuelling system.
Some of the pictures on this page link to Amazon.com where you can check price and delivery of products. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Stabil Fuel stabiliser
Mix this with the gas when winterising your small engine. Gas isn't what it used to be, it goes stale, in some cases after just one month. Bad gas causes gumming and that's a carburettor killer. Stabiliser will save you money and stress in the long run. Picture links to Amazon.com
Carburettor cleaner
When cleaning your carburettor you'll need this stuff. Gumming is a sticky substance that's hard to shift. The carb cleaner will remove it, however if your carb is really bad, save yourself some work, go ahead and buy a new carburettor. Picture links to Amazon.com
Oil extractor
You'll find this tool really useful if you need to drain the gas tank, and you will if the gas is stale. The siphon will remove it without fuss or mess and it can be used for extracting the oil too. Picture links to Amazon.com
Fuel line clamp
Some small engines will have a gas tap, which is really handy when removing the carburettor, stops gas flowing all over the shop. However most engines won't have one, these useful clamps simply squeeze the fuel line and prevent a spill while you perform surgery. Picture links to Amazon.com
Carburettor cleaners
You'll find these nylon brushes super useful when it comes time to clean those tiny passageways of the carburettor and jet. Use these in conjunction with the WD Carb cleaner. Picture links to Amazon.com
Ignition system tools
The ignition system of all small engines give plenty of trouble, after the fuelling system it’s the next most likely area to fail. Checking for spark is often the very first test we do. Check out this post “How to check spark”. Common problems include:
- Plug dirty
- Plug gap off
- Armature/Coil failure
- Broken flywheel key
The kind of tools we’ll need when working on an ignition system range from spark testing to measuring tools. I’ll list the most common tools together with what they do and a link to Amazon.
Spark Tester
This tool is used to check both the spark plug and the coil for spark. Sure you can check the spark without the tool, but it's not as good, the tool is designed to stress the whole ignition system. Picture links to Amazon.com
Spark plug gapper
This tool isn't strictly necessary if you have a feeler gauge, but it's a lot easier to handle. If you haven't guessed, you use this tool to check the gap of your spark plug, simple effective tool. Picture links to Amazon.com
Fly wheel puller
Now this tool is a must have if you're removing the flywheel. Why would want to remove the flywheel? Sometimes the flywheel key shears, it stops your engine starting. The key is really cheap and it's easy to fix when you've got this tool. Picture links to Amazon.com
DVOM
Every home needs a Dvom (Digital Volt Ohm Meter). It's used to check for continuity in lawn mower wiring, and for voltage when there's a battery fitted. But don't use this tool to check spark, that will kill it. I use mine everyday. I have the previous model to this and it's still doing its job. Picture links to Amazon.com
Jumper cables
Smart charger
Testing Compression
If you’re reading this section, you might have a more serous problem. But it doesn’t mean you can’t fix it. Small engines are really simple, they need 3 things:
- Gas/air mix
- Spark
- Compression
This tool will test compression, that in turn will help you identify common issues like head gasket failure, sticking valves or worn/broken piston rings.
Modern lawn mower engines use a compression release valve which help them start. Trouble is, a compression release valve will give you incorrect compression test readings.
So if your riding mower or walk behind mower was made in the last 15 years or so, you’ll need the leak-down tester.
It allows you accurately measure pressure loss in the cylinder (you’ll access to compressed air). But more importantly, it allows you listen for the tell tale leaking of air.
- Air from the dipstick indicates a broken or worn rings.
- Air leaking from exhaust/muffler suggests a exhaust valve issue.
- Air leaking from carburettor suggests an intake valve fault.
- Air from the cylinder head suggests a head gasket fault.
Compression tester
This is a compression tester, it's fitted in the plug hole using the adaptor. The engine is cranked over and a reading of how much compression the cylinder makes is captured on the gauge.
A low reading can be caused by a simple fault such as a sticking valve. Picture links to Amazon.com
Leak-down tester
Feeler gauge
John Cunningham is an Automotive Technician and writer on Lawnmowerfixed.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write "How to" articles that help fellow gear-heads with all aspects of mechanical repairs, from lawn mowers to classic cars.