Snowblower Runs Better On Half Choke? Solved

A snowblower that only runs on choke is irritating and besides it’s potentially bad news for the engine. You are correct to deal with this issue right now, it’s not a problem that will fix itself and will eventually result in a, no start, at best.

A snowblower that runs better on half choke likely suffers from a contaminated carburetor or a faulty carburetor. Cleaning or replacing the carburetor will fix the issue.

In this post you’ll learn how to successfully diagnose the root cause of the problem. You’ll learn how to clean the carburetor, together with tools and cleaning products needed. You’ll also learn when and how to replace the carburetor, including ordering the correct carburetor.

Mower gas cap

Vented Gas Cap

Diagnosing Snowblower Runs Better On Choke

Snowblowers like lawnmowers and most other small engine garden equipment are only employed for a few months of the year. Problems often arise at the beginning of the new season especially when the kit hasn’t been serviced or stored correctly.

I don’t blame equipment owners, we all live busy lives and servicing or storage preparation often isn’t high on the list.

Although when we need equipment, we need it now and it needs to be reliable. A little later in this post I’ll share a mechanics top tip for a trouble free start to the new snow season.

So what’s the problem, why does the snowblower run better with choke? Well the problem likely began at the end of last season. Gas goes stale and when it does, it often congeals inside the carburetor.

The old gas turns to gummy mess which easily clogs the fine fuel feed ports of the emulsion tube. Less fuel equals less power, however as you found out, applying choke makes the engine run smoothly.

The reason for this is simple and you’ve likely guessed it already, applying choke adds gas. Applying the choke replaces the missing fuel caused by the partially blocked carburetor.

A carburetor is a finely balanced component and although the engine may seem to run well on the choke, it isn’t designed to.

An engine that runs rich (getting too much gas) can cause more serious problems, like engine oil contamination which can result in crankshaft bearing damage.

An engine that runs lean (not enough gas) can cause excessive heat, valve damage which may result in engine seizure.

Diagnosing is easy, your description of the problem is pretty conclusive with gas starvation (not enough gas).

In order to confirm our suspicion we’ll need to remove the gas bowl and check for sludge. But just before we do that we’ll need to shut off the gas to the carburetor.

Removing the gas bowl before shutting off the gas will cause the gas to leak from the gas tank.

Most snowblowers are fitted with a fuel valve. Its function is to control gas flow, turning the tap clockwise to shut off the gas. Not all snowblower engines are fitted with a tap but if yours is, it will be fitted between the gas tank and carburetor.

If you don’t have a tap fitted, go ahead and use a fuel line clamp or needle nose vice grips to gently pinch the fuel line.

Removing the gas bowl before shutting off the gas will cause the gas to leak from the gas tank.

Now we are set to remove the gas bowl. Go ahead and locate the carburetor gas bowl, it’s fitted behind the air filter housing. It’s usually fixed in place with one fastener at its base.

Have a rag handy and wear gloves, the contents of the bowl will leak when the fastener is loosened.

Check the bowl for sludge and grit, finding contamination in here means you have confirmed your suspicion. The best fix is to remove and clean the carburetor. And that’s exactly what we’ll do in the next section

Mower gas tank

Winged & Threaded caps

How To Clean Snowblower Carburetor

In some cases removing the bowl, cleaning, refitting and turning the gas back on fixes the problem. Refitting the bowl after cleaning is worth a try. However, for most, carburetor removal and cleaning is the only fix.

tools you'll need

Most snowblower engines are easy to work on and you’ll likely already have all the tools you need to nail this repair. You will however require carb cleaner, this stuff is chemically engineered to remove gumming and so I’d say carb cleaner is mission critical to nailing this job.

You can check out the carb cleaner I use here on the “Snowblower maintenance tools page”.

In addition you’ll need the following:

  • Grips or fuel line clamp
  • Pointy nose pliers
  • Screwdrivers flat and Philips
  • Small socket set
  • Wrench set
  • Carb cleaner brush

removing snowblower carburetor

Removing the carburetor is usually pretty simple. Follow these basic steps:

  • Begin by turning off the gas tap or clamping off the fuel line as before
  • Remove the air filter cover and air filter. A couple of fasteners usually hold the air filter housing to the engine, these fasteners often double as the carburetor fasteners too.
  • Remove the crankcase breather pipe from the rear of the air filter housing and remove the housing and set it aside
  • With greater access to the gas line, go ahead and maneuver the gas line clamp using a pliers and use a flat driver to pry off the gas line
  • Before removing the choke arm from the carburetor take a picture of it routing and connection point
  • Before removing the governor arm take a picture of the routing and connection point. Turning the carburetor sideways when removing often helps unhook choke and governor arms
  • Before removing the carburetor take a picture of the gasket orientation and location. Incorrectly refitting gaskets will cause the engine to surge.

cleaning snowblower carburetor

As said earlier to nail the cleaning procedure we’ll need carb cleaner and some small carb cleaning brushes would be nice but not essential.

Before cleaning the carb we’ll need to strip it.

Follow these steps:

  • Remove bowl
  • Remove float and needle
  • Remove jet
  • Remove Emulsion tube (some may be fixed)Remove fuel adjustment screw (If possible) – Important to count & note the number of turns to remove the screw
  • Use carb clean on all carb components, all ports of the carburetor and use a wire to clean Emulsion tube (I use a wire brush strand)
Vented mower gas caps

Vented gas caps

Mechanics tips when rebuilding & refitting carburetor

  • Before refitting the clean or new carburetor, it’s best to check gas flow from the tank. Poor flow indicates a bad gas cap or fuel filter blockage. Most engines will have a bottle gas filter in the gas line which is easily changed. Others may use a filter concealed in the fuel line at the tank and others still may employ a mesh screen at the bottom of the gas tank. Use a sealable container to catch the stale gas, release the fuel line clamp to test flow.
  • If your snowblower gas is older than one month, now’s the time to drain it off and change that gas filter.
  • Rebuilding the carburetor isn’t much of a challenge, it’s the reverse of what we just did. However, refitting the gaskets and seals to their correct location and refitting the fuel adjustment screw to the correct number of turns is very important
  • Use your phone pictures as a guide when refitting the choke and governor arms, these arms are easy to get wrong
  • Turning the carburetor sideways will help with attaching both the governor and choke arms
  • When fitting the gas bowl, be careful to check the bowl seal is in place and resist over tightening the bowl fastener
  • Attach the fuel line, fill the tank with fresh gas, turn gas on and check line and bowl for leaks
  • Remember to refit the breather hose to the rear of the air filter housing before fitting
  • Clean or replace the air filter

How to avoid carburetor gumming

To avoid the problem of stale gas next season? Easy! simply add a gas stabilizer to your snowblower gas tank towards the end of the season.

Gas stabilizer is an additive for the gasoline. It keeps the gas fresh for up to 2 years and can be used in all small engine kit Lawnmowers, outboard motors, dirt bikes, ATV’s and two stroke engines like hedge trimmers, chainsaws and weed eaters etc.

Every year I see more and more problems with stale gas. The issue is blended gas, the alcohol in the fuel is causing the fuel to degrade and it also attacks the rubber components like seals and fuel lines.

A gas stabilizer will protect the rubber components also, it’s important to use it in ALL of your small engine kit. You are welcome!

Gas stabilizer is an additive for the gasoline. It keeps the gas fresh for up to 2 years and can be used in all small engine kit Lawnmowers, outboard motors, dirt bikes, ATV’s and two stroke engines like hedge trimmers, chainsaws and weed eaters etc.

When To Replace Snowblower Carburetor

Sometimes just looking at a carburetor is enough to let you know it needs replacing, but it’s not always apparent.

So here’s a short list of scenarios where I’ll pull the trigger and fit a new carburetor:

  • I removed the carburetor, cleaned it, refitted correctly and the engine still requires choke to run smoothly
  • I remove the bowl and it’s filled with rust
  • I remove the bowl and it’s thick with white chalk, congealed or gummed gas
  • If the carburetor is about the same or less than the cost of the labor and materials to clean it
  • If the carburetor is more than 10 years old

How To Order Replacement Snowblower Carburetor

The obvious way to order a new carb is to contact your local dealer with the snowblower product number and year of manufacture, but there is another way.

Many manufacturers don’t actually make their own carburetors, they in fact buy them from carburetor manufacturers like Walbro, Zama, Tillotson etc. Carb manufacturers make carburetors to suit many machines.

You likely don’t need to find a main dealer for your snowblower in order to buy a replacement carburetor Many online retailers offer the same parts at better prices and delivered to your door.

Identifying your carburetor is easy, they are all marked with a part number, simply match the part number.

I’ve listed many of the most common snowblower carburetors on this page, “Carburetor types” all conveniently delivered by Amazon.com.

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Auto Technician and Writer at Lawnmowerfixed | Website

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.