By: Author John Cunningham. Published: 2020/03/10 at 8:34 pm
Running your chainsaw dry comes with some risks, but there’s another option that’s simple and inexpensive. You’ll be glad you read this.
Should I run my chainsaw dry? Never run your chainsaw dry; instead, use a quality gas stabilizer. A stabilizer will keep fuel fresh and protect a chainsaw fuel system from damage caused by stale gas.
In this guide, you’ll learn the risks associated with running your saw dry; you’ll understand what components are at risk and also a foolproof alternative to running your saw dry. This stuff is basic; you won’t need a degree in engineering to apply this knowledge.
Don’t Run a Chainsaw Dry
I know plenty of people who run their kit dry when not in use, and for most, it works out just fine. However, running your saw dry can cause the finely balanced and delicate carburetor components to become problematic.
Symptoms of bad gas, as you likely know, affect new saws and old saws alike. Although the gas may have been drained from the tank and the engine running to a stop. The carburetor components still have a residue, and that can cause problems as it crystallizes.
Carburetor Parts at Risk
Most small-engine fuel systems are operated by gravity, lawnmowers, snowblowers, tillers, etc. So long as the gas tank is higher than the carburetor, a constant gas flow is available.
Need info on a 2-stroke carburetor – check out – How does a 2-stroke carburetor work?
Small engine handheld equipment, however, isn’t always held with the gas tank above the carburetor, so a fuel pump is needed to ensure a constant gas supply. Your saw fuel pump is a diaphragm, basically, a rubber gasket cleverly designed to act as a pump. The pumping action is powered by the rotational movement of the engine; it creates a pulsing vacuum.
The pulsing is what moves the gas from the gas tank to the carburetor, no matter what level the gas tank is positioned.
The fuel supply is proportional to engine speed. More engine speed (revs) equals more fuel supply. A wonderfully clever system.
Carburetor Diaphragm Gasket
The rubber diaphragm is designed to be flexible; it’s mission-critical. The gas and two-stroke oil help keep the rubber conditioned. As you’ve likely guessed, running the fuel system dry dries out the diaphragm material, making it stiff.
You’ll find it difficult to start a chainsaw engine with a dry, stiff diaphragm gasket, and the only fix is to go ahead and replace it.
If the saw does start, you may find it bogs down when working.
There are lots of causes of bogging, but a diaphragm that isn’t supple enough to move a plentiful supply of gas is high on the list of suspects.
Carburetor Needle Valve
The diaphragm has two important functions: supply the gas to the carburetor, as you know, but it also helps control the needle valve. The needle has a rubber tip that seals a fuel inlet port inside the carburetor. When the needle tip is in the needle seat (default position), gas can’t flow to the engine.
The diaphragm’s second function is to press on the needle metering valve arm. The valve arm is a spring-loaded lever that pushes the needle into the needle seat (default position). As the diaphragm pulses, it presses on the lever, allowing the needle to lift and gas to enter the system.
So what’s the problem? The needle seal (rubber tip), like the rubber diaphragm, is designed to be submerged in gas and oil.
Allowing it to dry out may cause the needle to stick in the closed position, which, as you know, blocks the gas flow. A pink-colored needle tip means it’s worn.
Fixing a Sticking Carburetor Needle Valve
In theory, fixing a sticking needle valve is an easy enough problem to solve. The valve simply needs a little nudge to break the seal. Often, just filling the saw with fresh gas, turning it over a few times, and leaving it to sit for a day or so becomes a nonproblem. If that fails, you’ll need to roll up the sleeves and clean the carburetor.
Some carburetors are easy to access, and some will be a total pain in the jacksie. If you’re going to the trouble of removing the carburetor, you might as well clean it and replace all gaskets and needle valves. You can buy a complete gasket repair kit or just replace the whole carburetor; most aren’t that expensive.
Buying a Carburetor
Although some carburetors may look identical, they are calibrated to your engine size. The wrong carburetor will supply too much gas or not enough; be sure to fit the correct carburetor.
Your old carburetor will have a code cast or stamped into the carburetor body; use that code to order your new carburetor. Some saw manufacturers make their own carburetors, but most fit third-party carburetors. Walbro and Zama are quality, popular carb manufacturers.
I’ve listed all the most popular ones here, together with the tools you’ll need to fit; check out “Chainsaw parts & tools.”
Use a Gas Stabilizer
My top tip is to use a gas stabilizer. It offers the very best protection for your saw’s fuel system. It removes any risk of gumming, which, as you know, is nasty crap that will cost you a packet to repair. The stabilizer will keep your gas fresh and protect your carburetor from gumming.
You can use it in all your small engines, from lawnmowers to chainsaws, 2-stroke, and 4-stroke. It’s not a substitute for two-stroke oil; you still mix the oil and gas as per normal.
I’ve listed a gas stabilizer on my “Chainsaw parts & tools” page.
How To Use Gas Stabilizer
Simply mix the bottle of stabilizer in your refueling can to the ratio specified. Then mix it with two-stroke oil as per your saw user manual (stabilizer is not a two-stroke oil substitute). Your equipment won’t be protected until you run the engine for a while to distribute the mixed gas throughout the fuel system.
You may also find “Chainsaw trouble-shooting” section helpful.
How do I winterize my chainsaw? To winterize a chainsaw, follow these seven simple steps:
- Remove bar and chain
- Clean sawdust from the saw body, chain and bar
- Clean air filter
- Store saw with choke on
- Fill bar oil reservoir
- Fill tank with fresh gas, add fuel stabilizer and run engine
- Spray saw with WD40 and store in dry environment
- About the Author
- Latest Posts
John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.