Snowblower Starts then Dies – Quick fix

By: Author John Cunningham. Published: 2023/06/15 at 4:29 pm

Nothing is more frustrating than the temperamental kit; not to worry, you are in the right place. I’m a mechanic, and we’ll get you fixed up and moving snow very shortly. Okay, let’s get stuck in!

The top three common causes of a Snowblower that start but then dies are:

• Stale gas
• Fuel starvation
• Fouled spark plug

In this post, we’ll cover the common causes of a start and immediate shutdown, and we’ll cover the less common reasons, too; we’ll cover the diagnosis process and the recommended repair for each.

Starting Procedure

Before we start diagnosis, covering the starting procedure for cold weather use is important. I know you know how to start your machine; you’ve likely been doing it for years. That said, here’s a quick 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 air-to-fuel ratio, and cold air carries a ton more oxygen than hot air. A cold-starting engine needs a little extra gas to get it running.

Snowblowers are designed to be used in low temperatures, so cold starting will always be a challenge for them. To that end, manufacturers offer two features to add extra gas for cold starting: the choke lever and the primer bulb.

The snowblower start process looks like this:

Move the choke back to half when the engine starts and turn choke off altogether when the machine is warm. That’s how to start a snowblower, and if your machine fails to start or stay running, then we’ll need to move on and do some diagnosis.

Stale Gas

Stale gas is a particular issue for all small engines and increasingly so over the last few years as ethanol-blended fuels are becoming mainstream.

Basically, blended gas goes stale quickly; how quickly depends on how the gas is stored. But when gas loses its vitality, your machine will struggle to start and stay running.

Stale gas diagnosis

Stale gas fix

If your gas tank level is low, I recommend adding just enough (about as much again) fresh gas to the tank to dilute the old gas and then try starting. It may take a few attempts to push the old gas through the system, but you may have some success. (don’t fill the gas tank, as this step may not work, and no sense wasting good gas)

It may take a few attempts to push the gas through the system.

Drain bowl as follows:

If you need more detail, check out – Carburetor bowl cleaning

Now go ahead and turn the fuel valve on again and attempt a start as before; if it now runs fine, great! (consider adding a fuel stabilizer to help prevent carburetor gumming and stale gas)

If, however, it won’t stay running, we’ll need to do a little more detective work.

Fouled Spark Plug

Okay, so why are we checking the spark plug?

Checking for a fouled spark plug eliminates it at an early stage which makes sense since checking it is easy and fast when compared to running carburetor checks.

Plug fouling diagnosis

To check for plug fouling, we’ll need to remove the spark plug, which with a plug tool, is a simple process.

To remove the plug:

• Locate the spark plug wire
• Remove the plug wire
• Fit the plug wrench
• Turn counter-clockwise

With the plug removed, check the color and condition of the electrode. A fouled plug may look wet, sooty, or possibly oily (see how to read a spark plug here). Either way, clean the plug with a wire brush, contact cleaner, or carb cleaner, or use a naked flame for oily plugs.

I’ve covered plug cleaning previously – Plug cleaning video.

Check the plug gap also – Gapping a spark plug

Before we refit the plug, we’ll check it’s making a good spark and doing so consistently.

Spark plug check

We’ll test the ignition spark in two ways: the DIY method, and I’ll cover using an inline ignition tester. An inline is the best way to check the spark as it stresses the whole system, great for finding intermittent ignition issues.

If the spark looks weak, try swapping out the spark plug (new or just a known good one), and if it still looks weak, replace the coil. I’ve covered replacing the coil previously, and you can check it out here – Coil/armature replacement

If all checks out okay with the spark, we’ll move on and check the fuel system.

Fuel Starvation

A fuel starvation issue is a very common reason for a start-stop symptom. The combination of blended gas, small engines, and summer or winter storage is a constant challenge for homeowners. It causes no end of problems.

As you know, blended gas in our machines goes stale and losses its potency but not only that, left long enough in damp cold storage conditions (pretty much every garage), the fuel evaporates and leaves behind a concoction of chemicals and water which blocks up the carburetor’s jets.

Heads up, that’s likely what we are dealing with here.

Fuel starvation diagnosis

If your carburetor is dirty, removing the bowl will reveal how bad it is. But just before we do that, we’ll check that our problem isn’t a fuel flow issue caused by a clogged fuel filter or bad gas cap.

We’ll test both first before removing the carburetor gas bowl.

Test fuel flow as follows:

• Turn gas valve off
• Locate the carburetor bowl
• Remove the bowl drain & drain into an old cloth
• Turn gas valve on and check flow

If the flow is good, you can jump to the gas bowl removal and inspection here.

If, on the other hand, the flow doesn’t improve, we’ll need to inspect the fuel system. Fuel feed systems are gravity systems; most use a filter or screen to remove dirt. Some filters are inline or maybe gas tank integrated.

Possible issues include:

• Filter blockage – remove and check the filter is clean.
• Tank debris – check tank for grit; rust in metal tanks is common.
• Collapsed fuel line – old lines may collapse or leak.
• Faulty carburetor valve – check for a faulty carburetor float valve, which often supplies too much gas or not enough.

Gas Bowl Removal & Inspection

If you need more detail on bowl removal, check out – Carburetor bowl and jet cleaning

Removal is as follows:

• Turn gas valve off
• Loosen & remove the bowl fastener
• Drain contents into old cloth

Inspect both the fastener and the bowl.

If, on the other hand, the contamination is mild, we can try cleaning the bowl and fastener if your fastener is jet integrated. Many carburetors employ the jet-integrated bowl fastener, and very often, just cleaning these jets, and the bowl is enough to fix our problem; I advise you to give this a try.

Here’s how I clean the bowl and jet.

If you need more detail on bowl removal & cleaning, check out – Carburetor bowl and jet cleaning

Go ahead and refit the bowl. Be careful not to pinch the bowl gasket and avoid over-tightening the bowl fastener. Now try and start your machine, remembering to turn on your gas tap.

If you are back in business, great! We had a pretty easy win. If that didn’t work, not to worry; it just means we need to remove and clean the carburetor.

Summary

Stale gas, fuel starvation, and a fouled spark plug are the three common reasons a snowblower may start but then die. The proper starting procedure for cold weather involves using the choke and primer bulb.

If the issue is stale gas, it can be diluted with fresh gas or drained and replaced. A fouled spark plug can be cleaned or replaced.

Fuel starvation is another possibility and is typically caused by a blocked fuel filter, a faulty gas cap, or problems with the carburetor. Cleaning or replacing the carburetor may be necessary to resolve the problem.

You may find the following posts helpful:

• Carburetor bowl cleaning
• Carburetor cleaning
• Carburetor cleaning (video)
• Carburetor faulty
• Carburetor float & needle test
• Carburetor float & needle replacement
• Choke repair