Briggs and Stratton 675 Engine Troubleshooting (5 Pro Fixes)

Ever notice how a perfectly running engine can suddenly decide to throw a wrench in your wood-splitting plans? I’ve been there, staring at a silent Briggs & Stratton engine on my log splitter more times than I care to admit. It’s like the machine knows you’re finally free for the weekend and decides to take a break of its own. But don’t worry, I’m here to share my years of experience troubleshooting these reliable workhorses. We’ll dive into some common issues and the pro fixes I’ve learned along the way, so you can get back to turning logs into cozy winter warmth.

Briggs & Stratton 675 Engine Troubleshooting: 5 Pro Fixes to Get You Back in Action

The Briggs & Stratton 675 series engine is a popular choice for many outdoor power equipment applications, including log splitters, lawnmowers, and pressure washers. Its reliability is generally good, but like any engine, it can experience problems. Understanding the common issues and knowing how to address them is essential for keeping your equipment running smoothly, especially when you’re relying on it for crucial tasks like preparing firewood.

1. Engine Won’t Start: The Fuel System Deep Dive

This is probably the most common complaint I hear and have personally experienced. You pull the cord, and nothing happens. Or maybe it sputters and dies. Nine times out of ten, the issue lies within the fuel system.

Understanding the Fuel System

Before we start wrenching, let’s understand how the fuel system works. It’s a simple system, but each part plays a critical role:

• Fuel Tank: Holds the gasoline.
• Fuel Line: Carries fuel from the tank to the carburetor.
• Fuel Filter: Removes debris from the fuel.
• Carburetor: Mixes fuel with air to create a combustible mixture.
• Fuel Shut-Off Valve (if equipped): Controls fuel flow from the tank.

Step-by-Step Troubleshooting

1. Check the Fuel Level: This might seem obvious, but I’ve been caught out by this more than once! Make sure you have enough fresh fuel in the tank. Old fuel can degrade and cause starting problems. I recommend using fuel stabilizer, especially if the equipment will sit unused for extended periods.
2. Inspect the Fuel Line: Look for cracks, kinks, or leaks in the fuel line. Replace the line if you find any damage. A cracked line can introduce air into the fuel system, preventing the engine from starting.
3. Clean or Replace the Fuel Filter: A clogged fuel filter restricts fuel flow. Disconnect the fuel line at both ends of the filter and remove the filter. Inspect it for debris. If it’s dirty, try cleaning it with carburetor cleaner. If cleaning doesn’t work, replace it. I usually keep a spare fuel filter on hand.
   • Tool Specification: Fuel filter pliers or small hose clamps.

4. Check the Carburetor: This is where things get a little more complex, but don’t worry, I’ll guide you through it.

   • Carburetor Cleaning: The carburetor is responsible for mixing air and fuel. Over time, it can become clogged with varnish and deposits, especially if using fuel that contains ethanol.

     • Step 1: Remove the Air Filter: This gives you access to the carburetor.
     • Step 2: Spray Carburetor Cleaner: Spray carburetor cleaner into the carburetor throat while attempting to start the engine. If the engine starts briefly, it indicates a clogged carburetor.
     • Step 3: Remove and Disassemble the Carburetor: This requires some mechanical skill. Take pictures as you disassemble it, so you know how to put it back together.
     • Step 4: Clean the Carburetor Components: Use carburetor cleaner and small brushes or pipe cleaners to clean all the jets and passages. Pay particular attention to the main jet and pilot jet.
     • Step 5: Reassemble the Carburetor: Reassemble the carburetor carefully, referring to your photos.
     • Step 6: Reinstall the Carburetor: Reinstall the carburetor on the engine.

   • Case Study: I once had a log splitter that wouldn’t start after sitting idle for the winter. After checking the fuel line and filter, I suspected the carburetor. Upon disassembly, I found the main jet completely clogged with a green, gummy substance. After a thorough cleaning, the engine started on the first pull.

   • Check the Fuel Shut-Off Valve (If Equipped): Make sure the fuel shut-off valve is in the “on” position. It’s easy to overlook this simple step.

Strategic Insights

• Fuel Stabilizer is Your Friend: Always use fuel stabilizer, especially when storing your equipment for extended periods. It prevents fuel degradation and keeps the carburetor clean.
• Ethanol-Free Fuel: If possible, use ethanol-free fuel. Ethanol can damage small engine components and cause carburetor problems.
• Regular Maintenance: Regularly inspect and clean the fuel system components to prevent problems before they occur.

Relevant Technical Details

• Fuel Filter Replacement: Replace the fuel filter annually or after every 100 hours of operation.
• Carburetor Cleaner: Use a high-quality carburetor cleaner specifically designed for small engines.
• Tools: Screwdrivers, pliers, carburetor cleaner, small brushes, pipe cleaners.
• Cost: Fuel filter (around $5-$10), carburetor cleaner (around $5-$10).

2. Engine Starts But Runs Rough: The Ignition System Investigation

So, the engine starts, but it sounds like it’s gargling gravel? This is a common sign of an ignition system problem. The ignition system is responsible for creating the spark that ignites the fuel-air mixture in the cylinder.

Understanding the Ignition System

The key components of the ignition system are:

• Spark Plug: Creates the spark.
• Ignition Coil: Generates the high voltage needed for the spark plug.
• Spark Plug Wire: Connects the ignition coil to the spark plug.
• Flywheel: Contains magnets that interact with the ignition coil to generate electricity.

Step-by-Step Troubleshooting

1. Check the Spark Plug: This is the first place to start.

   • Step 1: Remove the Spark Plug: Use a spark plug wrench to remove the spark plug.
   • Step 2: Inspect the Spark Plug: Look for cracks, carbon buildup, or oil fouling. A healthy spark plug should have a light tan or gray color.
   • Step 3: Clean the Spark Plug: If the spark plug is dirty, clean it with a wire brush or spark plug cleaner.
   • Step 4: Check the Spark Plug Gap: Use a spark plug gap tool to ensure the gap is within the manufacturer’s specifications. The correct gap is usually printed on the engine’s shroud or in the owner’s manual. A typical gap for a Briggs & Stratton 675 engine is 0.030 inches.
   • Step 5: Test for Spark: Reconnect the spark plug wire to the spark plug. Hold the spark plug against the engine block (making sure the metal part of the plug is touching metal on the engine) and pull the starter cord. You should see a strong, blue spark. If you don’t see a spark, the ignition coil may be faulty.
   • Step 6: Replace the Spark Plug: If the spark plug is damaged or heavily fouled, replace it with a new one.
     • Tool Specification: Spark Plug Wrench (typically 13/16 inch), Spark Plug Gap Tool, Wire Brush.

   • Check the Ignition Coil: If the spark plug is good, but you’re still not getting a spark, the ignition coil may be the problem.

   • Step 1: Disconnect the Spark Plug Wire: Disconnect the spark plug wire from the spark plug.

   • Step 2: Test the Ignition Coil with a Multimeter: Use a multimeter to test the resistance of the ignition coil. The resistance should be within the manufacturer’s specifications. Consult your engine’s service manual for the correct resistance values.
   • Step 3: Check the Air Gap: The air gap between the ignition coil and the flywheel magnets is crucial for proper ignition. Use a feeler gauge to ensure the air gap is within the manufacturer’s specifications. A typical air gap for a Briggs & Stratton 675 engine is 0.010-0.014 inches.
   • Step 4: Replace the Ignition Coil: If the ignition coil is faulty, replace it with a new one.
     • Tool Specification: Multimeter, Feeler Gauge, Screwdrivers.

Strategic Insights

• Spark Plug Maintenance: Replace the spark plug annually or after every 100 hours of operation.
• Correct Spark Plug: Use the correct spark plug for your engine. Using the wrong spark plug can damage the engine.
• Air Gap Adjustment: Ensure the air gap between the ignition coil and the flywheel magnets is properly adjusted. An incorrect air gap can cause weak spark or no spark at all.

Relevant Technical Details

• Spark Plug Torque: Tighten the spark plug to the manufacturer’s specified torque. Over-tightening can damage the cylinder head.
• Ignition Coil Resistance: Consult your engine’s service manual for the correct ignition coil resistance values.
• Tools: Spark plug wrench, spark plug gap tool, wire brush, multimeter, feeler gauge, screwdrivers.
• Cost: Spark plug (around $5-$10), ignition coil (around $20-$50).

3. Engine Overheats: The Cooling System Checkup

An overheating engine is a serious problem that can cause significant damage. It’s like running a marathon without water – eventually, something’s going to break down. The cooling system is designed to dissipate heat and keep the engine running at a safe temperature.

Understanding the Cooling System

The main components of the cooling system are:

• Cooling Fins: Located on the cylinder head and cylinder block, these fins dissipate heat into the air.
• Air Shroud: Directs airflow over the cooling fins.
• Flywheel Fan: Creates airflow to cool the engine.

Step-by-Step Troubleshooting

1. Check for Obstructions: The most common cause of overheating is obstructions blocking airflow over the cooling fins.

   • Step 1: Inspect the Cooling Fins: Check the cooling fins on the cylinder head and cylinder block for debris such as grass clippings, leaves, or dirt.
   • Step 2: Clean the Cooling Fins: Use a brush or compressed air to clean the cooling fins.
   • Step 3: Inspect the Air Shroud: Make sure the air shroud is properly installed and not damaged. The air shroud directs airflow over the cooling fins.
   • Step 4: Check the Flywheel Fan: Make sure the flywheel fan is not broken or damaged. The flywheel fan creates airflow to cool the engine.

2. Check the Oil Level: Low oil level can also cause overheating.

   • Step 1: Check the Oil Level: Use the dipstick to check the oil level.
   • Step 2: Add Oil: If the oil level is low, add the correct type of oil to the engine. Refer to your engine’s owner’s manual for the correct oil type and capacity.

3. Check the Carburetor: A lean fuel mixture (too much air, not enough fuel) can cause the engine to run hot. Refer to the carburetor troubleshooting section above to ensure the carburetor is properly adjusted.

Strategic Insights

• Regular Cleaning: Regularly clean the cooling fins to prevent overheating.
• Proper Oil Level: Maintain the correct oil level to ensure proper lubrication and cooling.
• Air Shroud Inspection: Inspect the air shroud regularly to ensure it is properly installed and not damaged.

Relevant Technical Details

• Oil Type: Use the correct type of oil for your engine. Refer to your engine’s owner’s manual for the correct oil type and viscosity.
• Oil Level: Maintain the oil level at the “full” mark on the dipstick.
• Tools: Brush, compressed air, screwdrivers.
• Cost: Minimal, primarily elbow grease!

4. Engine Smokes: The Internal Inspection

Engine smoke is a sign of internal problems. The color of the smoke can provide clues about the nature of the problem.

Understanding Engine Smoke

• Blue Smoke: Indicates burning oil. This could be caused by worn piston rings, valve seals, or a damaged cylinder.
• Black Smoke: Indicates a rich fuel mixture (too much fuel, not enough air). This could be caused by a clogged air filter, a faulty carburetor, or a stuck choke.
• White Smoke: Can indicate burning coolant (if the engine is liquid-cooled, which the 675 series is not) or, more commonly, water vapor. This can be normal on startup, especially in cold weather. However, persistent white smoke can indicate a blown head gasket (again, less common on this engine, but possible).

Step-by-Step Troubleshooting

1. Identify the Smoke Color: Determine the color of the smoke to help diagnose the problem.

2. Check the Air Filter: A clogged air filter can cause black smoke.

   • Step 1: Remove the Air Filter: Remove the air filter from the engine.
   • Step 2: Inspect the Air Filter: Inspect the air filter for dirt and debris.
   • Step 3: Clean or Replace the Air Filter: Clean the air filter with compressed air or replace it with a new one.

3. Check the Carburetor: A faulty carburetor can cause black smoke or blue smoke. Refer to the carburetor troubleshooting section above to ensure the carburetor is properly adjusted.

4. Check the Oil Level: An overfilled oil level can cause blue smoke.

   • Step 1: Check the Oil Level: Use the dipstick to check the oil level.
   • Step 2: Drain Excess Oil: If the oil level is too high, drain the excess oil.

5. Internal Engine Damage: If you’ve ruled out the above causes and the engine is still smoking blue, it’s likely due to internal engine damage. This requires more extensive repairs, such as replacing the piston rings or valve seals. This is often best left to a professional mechanic.

Strategic Insights

• Air Filter Maintenance: Regularly clean or replace the air filter to prevent engine smoke.
• Proper Oil Level: Maintain the correct oil level to prevent engine smoke.
• Professional Assistance: If you suspect internal engine damage, consult a professional mechanic.

Relevant Technical Details

• Air Filter Replacement: Replace the air filter annually or after every 25 hours of operation in dusty conditions.
• Oil Type: Use the correct type of oil for your engine. Refer to your engine’s owner’s manual for the correct oil type and viscosity.
• Tools: Screwdrivers, compressed air.
• Cost: Air filter (around $5-$10).

5. Engine Lacks Power: The Compression Test

If the engine starts and runs, but lacks power, it could be due to low compression. Compression is the measure of how tightly the air-fuel mixture is compressed in the cylinder. Low compression means the engine isn’t able to generate as much power. This is often felt when trying to split tougher logs.

Understanding Compression

Compression is essential for efficient combustion. Low compression can be caused by:

• Worn Piston Rings: The piston rings seal the gap between the piston and the cylinder wall. Worn piston rings allow air and fuel to leak past, reducing compression.
• Leaking Valves: The valves control the flow of air and exhaust gases into and out of the cylinder. Leaking valves allow air and fuel to escape, reducing compression.
• Blown Head Gasket: The head gasket seals the cylinder head to the cylinder block. A blown head gasket allows air and fuel to leak out, reducing compression.

Step-by-Step Troubleshooting

1. Perform a Compression Test: A compression test measures the amount of pressure in the cylinder.

   • Step 1: Warm Up the Engine: Run the engine for a few minutes to warm it up.
   • Step 2: Remove the Spark Plug: Remove the spark plug from the engine.
   • Step 3: Install the Compression Tester: Install a compression tester into the spark plug hole.
   • Step 4: Crank the Engine: Crank the engine with the starter motor until the compression tester needle stops rising.
   • Step 5: Record the Compression Reading: Record the compression reading on the compression tester.
   • Step 6: Compare the Reading to the Manufacturer’s Specifications: Compare the compression reading to the manufacturer’s specifications. A typical compression reading for a Briggs & Stratton 675 engine is between 75 and 125 PSI.

2. Interpret the Results:

   • Low Compression: If the compression reading is below the manufacturer’s specifications, it indicates low compression. This could be caused by worn piston rings, leaking valves, or a blown head gasket.
   • Good Compression: If the compression reading is within the manufacturer’s specifications, the engine has good compression.

3. Further Diagnosis: If the compression test indicates low compression, further diagnosis is needed to determine the cause. This may involve:

   • Leak-Down Test: A leak-down test measures the rate at which air leaks out of the cylinder. This can help pinpoint the source of the leak (e.g., piston rings, valves).
   • Cylinder Inspection: Inspecting the cylinder for wear or damage.

Strategic Insights

• Compression Testing: Perform a compression test regularly to monitor the health of your engine.
• Professional Assistance: If you suspect low compression, consult a professional mechanic for further diagnosis and repair.

Relevant Technical Details

• Compression Tester: Use a compression tester specifically designed for small engines.
• Compression Reading: Compare the compression reading to the manufacturer’s specifications.
• Tools: Compression tester, spark plug wrench.
• Cost: Compression tester (around $20-$50).

General Safety Considerations

Working with small engines involves potential hazards. Always follow these safety precautions:

• Disconnect the Spark Plug Wire: Before performing any maintenance or repairs, disconnect the spark plug wire to prevent accidental starting.
• Wear Safety Glasses: Wear safety glasses to protect your eyes from debris.
• Wear Gloves: Wear gloves to protect your hands from sharp objects and chemicals.
• Work in a Well-Ventilated Area: Work in a well-ventilated area to avoid inhaling harmful fumes.
• Use Proper Tools: Use the correct tools for the job to avoid injury or damage to the equipment.
• Read the Owner’s Manual: Read and understand the owner’s manual before operating or servicing the equipment.
• Fire Safety: Keep a fire extinguisher nearby when working with flammable liquids.
• Fuel Handling: Handle fuel carefully and avoid spills. Store fuel in approved containers away from heat and open flames.

Beyond the Fixes: Pro Tips for Long Engine Life

Beyond these specific troubleshooting steps, here are some general tips for keeping your Briggs & Stratton 675 engine running strong for years to come:

• Regular Oil Changes: This is the single most important thing you can do to prolong the life of your engine. Change the oil according to the manufacturer’s recommendations (typically every 25-50 hours of operation). I personally change the oil in my log splitter every season, regardless of how many hours I’ve used it.
• Air Filter Maintenance: Keep the air filter clean. A dirty air filter restricts airflow and can cause the engine to run poorly. Clean the air filter regularly with compressed air or replace it with a new one.
• Fuel System Maintenance: Use fresh fuel and add fuel stabilizer, especially when storing the equipment for extended periods. Clean the carburetor periodically to prevent clogs.
• Spark Plug Maintenance: Replace the spark plug annually.
• Proper Storage: When storing the equipment for extended periods, drain the fuel tank and carburetor to prevent fuel degradation.
• Preventive Maintenance: Follow the manufacturer’s recommended maintenance schedule.

Case Study: Reviving a Neglected Log Splitter

I once acquired a used log splitter that had been sitting neglected in a barn for years. The engine was a Briggs & Stratton 675 series, and it was in rough shape. The engine wouldn’t start, and the overall condition was poor.

Here’s how I revived it:

1. Fuel System Overhaul: I completely disassembled and cleaned the carburetor, replaced the fuel filter, and installed new fuel lines. The old fuel was thick and gummy, completely clogging the carburetor jets.
2. Ignition System Tune-Up: I replaced the spark plug and checked the ignition coil. The spark plug was heavily fouled, and the ignition coil air gap was incorrect.
3. Oil Change: I changed the oil and oil filter. The old oil was black and sludgy.
4. Air Filter Replacement: I replaced the air filter. The old air filter was completely clogged with dirt and debris.
5. Cooling System Cleaning: I cleaned the cooling fins and air shroud. The cooling fins were packed with grass clippings and dirt.
6. Compression Test: I performed a compression test to check the engine’s internal condition. The compression was within the manufacturer’s specifications.

After completing these steps, the engine started on the first pull and ran smoothly. The log splitter was back in action, ready to tackle a winter’s worth of firewood. This experience highlighted the importance of regular maintenance and proper storage.

Final Thoughts: Empowering You to Keep Your Engine Humming

Troubleshooting a Briggs & Stratton 675 engine can seem daunting, but with a little knowledge and the right tools, you can tackle many common problems yourself. Remember to always prioritize safety, follow the manufacturer’s recommendations, and don’t be afraid to seek professional help when needed. By understanding the fuel system, ignition system, cooling system, and other key components, you can keep your engine running smoothly and efficiently for years to come. Now, get out there and get that firewood split!

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