Troy Bilt Snowblower Surging? Stop Engine Pulsing NOW!
There are few things more frustrating than firing up your Troy Bilt snowblower on a snowy morning, only to hear the engine start pulsing and hunting. That unmistakable surge, where the engine revs up and down on its own, is not just annoying; it’s a clear sign that something is wrong. This surging is your engine’s way of telling you it’s struggling to maintain a steady speed.
Fortunately, this is a very common issue with a handful of well-known causes. In most cases, you can fix a surging Troy Bilt snowblower with some basic tools and a little bit of patience. This guide will walk you through everything you need to know to diagnose and solve the problem for good.
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What Causes a Troy Bilt Snowblower to Surge?
Engine surging, also known as “hunting,” happens when the air-to-fuel ratio in the engine is incorrect, typically running too lean (too much air, not enough fuel). The engine’s governor tries to compensate by opening the throttle to add more fuel, causing the RPMs to jump. Once it gets fuel, it over-revs, and the governor closes the throttle, starting the cycle all over again. The primary culprit behind this lean condition is almost always a fuel delivery problem.
The overwhelming number one cause of surging is a clogged carburetor. This is especially true for equipment that has sat for months with untreated gasoline in the tank. Modern ethanol-blended fuel can absorb water and degrade, leaving behind gummy varnish deposits that clog the tiny fuel passages inside the carburetor.
The Usual Suspects: Fuel System Breakdown
When your snowblower starts surging, the fuel system should be the very first place you investigate. The problem almost certainly lies in one of these areas:
- Clogged Carburetor Jets: The main jet and the pilot (or idle) jet have minuscule openings that are easily blocked by varnish from old fuel. A clogged idle circuit is a very frequent cause of surging.
- Old or Contaminated Fuel: Gas that has been sitting for more than 30-60 days can go bad. Water contamination, often from ethanol attracting moisture, can also lead to poor engine performance and surging.
- Dirty Fuel Bowl: The carburetor bowl can accumulate sediment and water over time, which then gets drawn into the carburetor jets.
- Clogged Fuel Filter: If your model has one, a clogged fuel filter can restrict the flow of gasoline to the carburetor, leading to fuel starvation.
Step-by-Step Guide to Fixing Your Surging Troy Bilt Snowblower
Follow these steps in order, starting with the easiest and most common fixes first. For any work on the engine, always disconnect the spark plug wire first as a critical safety measure to prevent accidental starting.
Step 1: Replace the Fuel
Before you start taking anything apart, eliminate the simplest cause. Drain all the old fuel from the tank and the carburetor. The easiest way to drain the carb is to loosen the bolt at the bottom of the float bowl.
Once empty, refill the tank with fresh, high-quality gasoline (87 octane or higher). For best results and to prevent future issues, use ethanol-free gasoline or add a quality fuel stabilizer to every tank. This is the single most important preventative step you can take.
Step 2: The Carburetor – Your Most Likely Solution
If fresh fuel doesn’t solve the problem, it’s time to address the carburetor. A dirty carburetor is the cause of surging engines more than 90% of the time. You have two options here: a quick clean or a full deep clean.
Method A: The Quick Clean (No Removal)
Sometimes, a minor blockage can be cleared without removing the carburetor. With the engine running, spray short bursts of carburetor cleaner directly into the air intake. This can sometimes dissolve small deposits in the main jet. However, this is often a temporary fix and is not effective for more stubborn clogs, especially in the idle circuit.
Method B: The Deep Clean (Full Carburetor Removal)
For a permanent fix, you need to remove and thoroughly clean the carburetor. While it may seem intimidating, it’s a straightforward process.
1. Remove Covers: You’ll likely need to remove a plastic engine cover or shroud to access the carburetor. This usually involves removing a few 10mm bolts.
2. Take a Picture: Before you disconnect anything, take a clear photo of the carburetor with your phone. Pay close attention to how the throttle linkages and governor springs are connected. This will be an invaluable reference during reassembly.
3. Disconnect Lines and Linkages: Clamp the fuel line to prevent gas from spilling, then disconnect it from the carburetor. Carefully unhook the governor rod and any springs from the throttle plate.
4. Remove the Carburetor: Unscrew the two bolts or nuts holding the carburetor to the engine block and remove it.
5. Disassemble and Clean: Place the carburetor on a clean workbench. Remove the float bowl nut and the bowl. Carefully remove the float pin, float, and needle valve. Unscrew the main jet from the center tube. Also, locate and remove the smaller pilot jet, which is often under a plastic screw on top of the carb.
6. Spray and Clear Passages: Using carburetor cleaner with a straw, spray through every single hole and passage you can find—the main jet, pilot jet, fuel inlet, and the emulsion tube (the tube the main jet screws into). Make sure the tiny holes on the sides of the emulsion tube are perfectly clear. For stubborn clogs, you can gently poke a thin wire (like a single bristle from a wire brush or a bread tie wire) through the jets to clear them. Never force the wire, as you can damage the brass jets.
7. Reassemble: Carefully put everything back together in the reverse order of disassembly. Use your photo as a guide to reconnect the linkages and springs correctly. A misconfigured governor linkage is also a cause of engine issues, something you can explore if cleaning the carb doesn’t solve the problem. Checking into something like a governor adjustment can sometimes be the final piece of the puzzle.
Step 3: Inspect the Governor System
The governor is responsible for maintaining a constant engine speed under varying loads. If the springs are stretched or the linkages are bent or binding, it can cause erratic engine behavior and surging.
Visually inspect the governor springs; they should be taut but not stretched out of shape. Move the throttle linkage by hand to ensure it moves freely without catching on anything. If a spring looks damaged, replacing it is an inexpensive and easy fix.
The Secret Culprit: A Clogged Emulsion Tube
Beyond the Main Jet
Many DIY repair guides focus solely on the main jet and pilot jet, but often the true cause of persistent surging lies deeper within the carburetor, in the emulsion tube. The emulsion tube, or main nozzle, is the hollow brass tube that the main jet screws into. Its job is to pre-mix air and fuel before it enters the engine’s throat.
This tube is perforated with a series of tiny, cross-drilled holes. When old fuel turns to varnish, these tiny holes become clogged. This disrupts the proper mixing of air and fuel, creating a lean condition that the governor constantly tries to correct, resulting in the classic surging sound. Even if the main jet itself is clear, a clogged emulsion tube will still cause significant running problems.
Troubleshooting Quick Reference Table
Use this table to quickly diagnose the potential cause of your surging issue.
| Symptom | Most Likely Cause | Recommended Solution |
|---|---|---|
| Engine surges at full throttle, no load | Clogged main jet or emulsion tube | Remove and deep clean the carburetor |
| Runs smoothly with choke on, surges with choke off | Clogged pilot jet (lean condition) | Thoroughly clean the carburetor’s pilot circuit |
| Engine hunts and RPM is erratic | Governor linkage binding or spring issue | Inspect linkages for free movement and check springs |
| Surging started after long-term storage | Old fuel and varnished carburetor | Drain all fuel and perform a deep carburetor cleaning |
Preventing Future Surging Problems
Once you’ve fixed the surging, you’ll want to make sure it doesn’t happen again. Prevention is simple and saves you from having to do these repairs every season. This is a common issue across many brands, even famously reliable ones like those covered in our Honda 828 guide.
Use Fuel Stabilizer: Add a high-quality fuel stabilizer to your gas can every time you fill it up. This will keep the fuel fresh for up to two years and prevent the formation of varnish and gum.
End-of-Season Prep: At the end of winter, don’t just put the snowblower away. Either run the engine completely out of fuel until it stalls or drain the tank and carburetor bowl. An empty fuel system can’t get clogged. Proper storage is key, whether for a workhorse machine or a classic like the Honda HS55.
When Should You Call a Professional?
While fixing a surging snowblower is a very manageable DIY task, there are times when it’s best to seek professional help. If you have performed a thorough carburetor cleaning, replaced the fuel, and checked the governor system, but the engine still surges, there could be a more complex issue, such as an air leak from a cracked intake gasket. If you’re not comfortable performing these steps or if the problem persists, a qualified small engine mechanic can diagnose and fix it efficiently.
