By: Author John Cunningham. Published: 2023/06/15 at 7:12 pm
A snowblower won’t start when cold isn’t an unusual complaint. I’m a mechanic with 20-plus years of experience, and very shortly, you’ll be moving snow.
A snowblower that starts fine when hot but won’t start when cold likely suffers from a choke or primer bulb issue; adjusting the choke plate or replacing the primer bulb will likely solve the problem.
In this post, you’ll learn why your snowblower refuses to start when it is cold and what you can do to diagnose and fix it right now.
If this is your snowblower’s first start of the season, your machine may be suffering from the effects of stale gas; if that is the case, I wrote a post all about a snowblower no-start, and you can check it out here – Won’t start after summer.
Snowblower Cold Starting Procedure
Before we start diagnosis, I like to ensure we are on the same page; I don’t want to waste your time. It is important to cover the starting procedure for cold weather use. You likely know how to start your machine; you’ve been doing it for years. That said, here’s a fast guide for those unfamiliar with choke or primer operation for cold starts.
A cold engine needs extra gas to help it start; it’s all about the optimum oxygen-to-fuel ratio (known as an air-to-fuel ratio or AFR), and cold air carries more oxygen than hot air; that’s why we need to add a little extra gas to start a cold engine.
Your car or truck does this automatically, and some lawnmowers do too, but on snowblowers, the operator must know how to use the machine’s cold start controls.
Starting a snowblower will always be challenging since we only use them in the cold.
To that end, manufacturers offer two features to make cold starting easier.
They are the choke lever and the primer bulb.
While manufacturers recommend you start your snowblower cold using the choke and primer bulb, some folks found they don’t need to; their snowblower will start just fine with one or other. That is, until the temperatures get properly low, then both controls are required.
Using cold weather starting controls look like this:
- Engine On
- Gas valve On
- The throttle is set to High
- Choke On Full
- Press Primer 4 times
- Pull start or electric start the machine
When the engine starts, move the choke back to half and turn the choke off altogether when the machine is warm.
Now that’s out of the way, let’s get into some proper diagnosis.
Snowblower Primer Bulb
The primer bulb, typically located on the plastic carburetor shield, allows the operator to add raw gas directly into the carburetor’s mouth, where it stands, ready to be sucked into the combustion chamber on the next intake stroke.
The primer bulb is great for quick starts but lacks fuel enrichment continuity.
Prinmer Bulb Diagnosis
While starting a snowblower without a functioning primer bulb is possible, it requires more effort and a longer crank. And in really cold conditions, it may not be possible at all.
Primer bulb diagnosis can often be made by examining the rubber bulb; as you can imagine, they wear out, perish, crack, and tear.
So a thorough examination of the bulb is our first check. Next, we must examine the air hose from the bulb to the carburetor. To do that, we’ll need to remove the plastic carburetor shield if not already removed. Check for disconnected ends, hose splits, or perished ends.
With the primer bulb assembly loose but connected, try priming the bulb and check the carburetor for raw gas. Raw gas should acuminate inside the carburetor. If that’s not happening, and the primer bulb and hoses look good; then it’s likely your carburetor will need to be removed and cleaned.
I’ve covered that previously in this post – Remove & clean carburetor
The snowblower choke is, as you know, required to help start a cold engine. We learned that the primer bulb is great for quick starts and gives the engine a fast shot of gas, but it lacks any follow-up; for that, we need an adjustable constant enrichment control, and that’s what the choke is all about.
The choke control is located on the plastic cover close to the carburetor.
Manufacturers use the word choke or a choke plate symbol to identify the choke lever control.
It’s called a choke because it’s a metal plate that, when in use, closes off the air intake to the carburetor restricting or choking off the supply of air to the engine and increasing the ratio of gas in the engine – exactly what a cold engine needs.
But the choke only adds extra gas as you crank over the engine, so getting it to fire with a choke alone will typically take longer and more effort.
The choke on most snowblowers is so simple it is hard to imagine an issue with them. It is possible, especially if a choke control is handlebar dash mounted. Those types may use a braided cable to apply the choke, and those guys require adjustment occasionally.
Let’s do some basic choke tests. The first thing we can do is check the choke control, and check whether it moves to the full-on position and feels normal. If the answer is no, we must remove the carburetor plastic shields and examine the choke plate in operation.
With the carburetor shields removed, check operation.
Move to choke to fully “On” position.
It should look like this image. If the plate doesn’t close or is restricted somehow, investigate it.
Otherwise, all is good here.
Other possible causes
There are always other possible causes for your hard or no cold starts; here are a few of them.
- Bad gas – fresh gas is critical. Bad gas will cause hard starting, no-start, and a range of running issues.
- Faulty carburetor – a faulty carburetor is temperamental, and symptoms range from no-start to rough running.
- Spark plug issues – a bad plug or coil can cause issues; that said, an ignition issue is more likely to show up with a hot start than cold, but still a possible contender.
If your snowblower doesn’t start when it’s cold, there are a few common issues to check. It could be a problem with the choke or the primer bulb. Adjusting the choke plate or replacing the primer bulb may solve the problem.
Stale gas can also affect the first start of the season. Make sure to follow the correct starting procedure for cold weather, which involves using the choke and primer bulb.
Other possible causes include bad gas, a faulty carburetor, or spark plug issues.
You may find the following posts helpful
- About the Author
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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.