11 Reasons a Generac Pressure Washer Won’t Start (SOLVED)

When you are experiencing a starting problem with your pressure washer, begin looking for items that may be keeping the engine from getting sufficient air, fuel, and spark.

This may be due to a dirty carburetor, bad spark plug, faulty ignition coil, plugged air filter, incorrect engine oil level, faulty starter recoil, sheared flywheel key, or old fuel.

Keep reading for additional items that may cause your Generac pressure washer’s starting problem.

Stay safe when making repairs and follow the safety guidelines listed in your operator’s manual. Always remove the spark plug wire before performing repairs.

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Reasons for Your Generac Pressure Washer Starting Problem

1. Empty Gas Tank

I only mention checking the fuel supply in the tank just in case you skipped this step and moved on to other items on the pressure washer.

You may have forgotten the last time you added fuel. You may have developed a fuel leak or your fuel gauge is not working right.

I only mention this obvious cause of a starting problem because it’s easy to forget when you’re frustrated.

SOLUTION: Add fresh gasoline to the fuel tank.

2. Bad or Old Fuel

Gas can begin to break down rather quickly. This is why you should consume gas within 30 days of purchasing it to ensure you use gas before the ethanol negatively affects the fuel system.

Ethanol, found in most gasoline used today, attracts moisture to the fuel system. As this ethanol and water mixture evaporates it leaves behind a varnish that can cause component failure and fuel restrictions.

In addition to deposits left behind by this mixture, water in the fuel system is corrosive to the fuel system and engine.

Because of the adverse effects ethanol has on a Generac pressure washer, it’s important to keep these things in mind when purchasing, storing, and consuming fuel:

• Purchase fresh fuel with a minimum 87 octane rating (91 RON).
• Never use gas with more than a 10% ethanol content. Ethanol-free fuel is best.
• Consume fuel within 30 days.
• Use a fuel stabilizer if you cannot consume it within 30 days to make it last a little longer without breaking down. (Fuel stabilizer must be added to fresh fuel. It will not reverse the effects of old fuel).
• Store fuel in an approved fuel container away from moisture or combustible products.

SOLUTION: If you find old fuel in your Generac pressure washer, drain the fuel using a fuel siphon pump. Mix fresh gas with a fuel additive to help clean the fuel system, reduce moisture, and stabilize the gas.

Add gas to the fuel tank. Once you are able to get the pressure washer to start, allow it to run for about 15 minutes so the gas and stabilizer mixture is able to work its way through the fuel system.

I like a product called Sea Foam Motor Treatment. I use this product in every tank of gas to help reduce the issues that can result from using fuel with ethanol. Another good option is STA-BIL.

3. Dirty Carburetor

Your Generac uses a carburetor to regulate the amount of gas that is mixed with air to be ignited to start the pressure washer.

When the carburetor is dirty and gums up from old fuel, components in the carburetor no longer function properly. The carburetor may not allow the gas required to start your Generac pressure washer.

After you have verified you are getting fuel to the carburetor, you need to take a look at the carburetor. This is a common part that can gum up and leave behind crusty deposits from old gas.

SOLUTION: Remove the carburetor and clean it with a carburetor cleaner to remove varnish and deposits forming in the carburetor.

Take a look at the carburetor float, float needle, and fuel jets to make sure they are sufficiently clean and in good condition.

If you find any damaged parts, you must replace them using a carburetor rebuild kit or a replacement carburetor.

4. Plugged Air Filter

An air filter is installed to keep dirt and debris from entering through the air intake. This is to protect the engine from damage that can be caused by just a small amount of dirt.

You must always run an air filter on your pressure washer and check the filter several times throughout the year to clean it and ensure it is in good condition. Running your pressure washer without an air filter can void the warranty on the engine.

I recommend replacing the air filter annually and cleaning it a few times throughout the year for the average homeowner.

When you notice the filter is extremely dirty or damaged, you must replace it. You will definitely need to replace it more often if you are running the pressure washer in dry dusty conditions.

If you are not cleaning and replacing the filter regularly, the filter can become plugged with so much dirt that the engine won’t get sufficient air. It can overheat and cause extensive permanent engine damage.

SOLUTION: If you find your air filter is plugged, clean it using the procedure below for your type of air filter.

If you are unsure of the type of filter you have and its cleaning procedure, consult the operator’s manual as the filter used will vary by engine manufacturer and model.

Clean a foam-style air filter

• Remove the air filter from the housing.
• Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
• Inspect the foam filter for damage and replace it if needed.
• If the filter is in good condition, clean it in soapy water and rinse it until the water runs clear.
• Squeeze the filter and allow it to dry.
• Coat the filter in clean engine oil so it is fully covered, but not dripping with oil. Squeeze the filter to remove excess oil. (Do not apply oil to a foam pre-cleaner used with a paper air filter)
• Install the air filter.
• Reattach the air filter cover.

Clean a paper air filter:

• Remove the air filter from the housing.
• Remove the foam pre-cleaner.
• Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
• Inspect the paper air filter. Tap the filter to loosen dirt so it falls from the filter. If the filter is very dirty, damaged, or no longer seals the air intake sufficiently, replace it with a new one.
• Wash the foam pre-filter in mild detergent and water solution. Rinse to remove dirt and soap. Squeeze and allow to dry.
• Install the paper air filter and foam pre-cleaner.
• Reattach the air filter cover.

5. Fouled Spark Plug

A spark plug can be faulty when the tip is dirty, the porcelain is cracked or the electrode is burnt. This will cause your pressure washer not to start because of a lack of spark.

SOLUTION: You can clean the spark plug to remove the deposits on the tip. If your spark plug tip is very dark in color or damaged, you must replace it with a new one.

Your spark plug needs to be properly gapped following the manufacturer’s specifications as found in the operator’s manual.

Starting problems can be caused by a spark plug that is gapped incorrectly or a spark plug wire that is loose.

6. Bad Ignition Coil

Before checking for a bad ignition coil, make sure your spark plug is in good condition. The ignition coil provides voltage to the spark plug so it can start the engine.

If the spark plug isn’t able to fire due to a bad spark plug or ignition coil, the engine will not start.

SOLUTION: Check the continuity of the ignition coil using an ohmmeter. If you find a break in the continuity, replace the ignition coil.

7. Low Engine Oil Level

The pressure washer will not start when the engine oil is not at the correct level. Many Generac pressure washers have a sensor that recognizes a low engine oil level.

It will prevent the engine from running with a low engine oil level to protect the engine.

SOLUTION: To check the engine oil level, begin by placing the pressure washer on a flat-level surface. Remove the oil fill cap and wipe off the dipstick with a clean cloth to remove the oil.

Reinsert the dipstick into the oil-fill tube, but don’t screw on the cap. Remove it and look at the oil level on the dipstick. Ensure it is in the full range on the dipstick.

If it is not, correct the engine oil level by removing or adding a little oil until it is at the correct level.

When you find you have the correct engine oil level and the low oil sensor stays on, you may have a faulty sensor. It’s best to take the pressure washer to a service center to be repaired.

8. Wrong Choke Setting

The choke lever or knob (depending on your Generac model) is used to open and close the choke to change the amount of air allowed to be mixed with fuel to start the engine.

The choke lever must be placed in the choke position to start a cold engine. Once the engine warms it must be adjusted to the open position so the engine receives enough air to keep running.

SOLUTION: Make sure the choke is placed in the closed position to start a cold engine and the open position to start a warm engine.

9. Bad Recoil on a Manual Start Pressure Washer

When the starter recoil wears or parts of the recoil break, it’s hard or impossible to get the pressure washer started.

The rope on the recoil can become unstrung or the pulley, springs, or clips may break causing your starting problems.

SOLUTION: Sometimes, restringing the recoil is all you need. Other times you will have to replace broken parts in your recoil. Before replacing parts, price out a full recoil replacement.

Depending on the price difference, it may be better to replace the recoil assembly over tearing it down and replacing broken components.

10. Broken Flywheel Key

The flywheel key is a small part that is installed in the crankshaft to engage the flywheel. This key can become worn or sheared causing the timing to be off between the spark and the piston.

When this happens, the engine may not start.

SOLUTION: You may have to remove the flywheel to inspect the condition of the flywheel key. A sheared key must be replaced.

I recommend having a small engine mechanic perform work on your engine to ensure it is repaired correctly for safety reasons.

11. Compression Problem

While pulling the starter recoil rope, you may notice a loss of compression. When the compression is low on a Generac pressure washer, it will fail to have enough pressure to keep it running.

This can be the result of worn crankshaft seals, worn piston rings, or damage to the piston.

SOLUTION: I advise bringing your pressure washer to a small engine mechanic, Generac service center, or engine dealer for testing and making necessary repairs.