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11 Reasons a Generac Pressure Washer Starts, Stalls & Dies

You were able to get your pressure washer running, but it won’t keep running and just shuts down. When this happens, troubleshoot items that restrict air, fuel, and spark.

A Generac pressure washer starts and then dies due to an empty fuel tank, plugged fuel filter, dirty carburetor, clogged fuel components, bad fuel tank vent, dirty spark plug, faulty ignition coil, low engine oil level, or old gas.

Wait for the engine to cool and remove the spark plug wire before performing any repairs. Follow the safety precautions found in the Generac operator’s manual.

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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.

Your Generac Pressure Washer Starts Then Dies

1. Gas Tank is Empty

You know your Generac pressure washer won’t run without gas. This is common knowledge. I only mention it because, sometimes out of frustration, you forget to check this obvious reason.

You may have developed a fuel leak or the fuel gauge may have stopped working.

SOLUTION: Add fresh fuel to the pressure washer when it is running low or the tank is empty.

2. Old Fuel

Gas sitting in a pressure washer for a long period can leave behind a varnish that gums the fuel system and causes fuel restrictions. When less fuel is getting to the engine, the pressure washer will sputter and possibly die.

Because gas begins to break down as soon as 30 days after you purchase it, it’s important to purchase fresh gas and consume it within 30 days.

I know this is easier said than done. You may only use the pressure washer during a power outage and you never know how long that will be.

This is why you should add a fuel additive to fresh gas before you add it to the fuel tank. A fuel additive like Sea Foam Motor Treatment will stabilize gas and reduce moisture so it lasts a little longer.

Follow these tips to get the best fuel results:

  • 4-cycle pressure washers require unleaded gasoline with a minimum 87 octane rating and a maximum ethanol content of 10%. Don’t use gasoline with higher ethanol contents.
  • Use gas within 30 days.
  • Don’t leave gas outdoors where it can attract moisture.
  • Store gas in a dry place.
  • Only buy enough gas you can use within 30 days. If you purchase more than this, add a fuel additive to stabilize your gas.

SOLUTION: Drain old gas into a container to be disposed of properly. Add fresh fuel with a fuel additive to stabilize and clean the fuel system.

3. Fuel Blockage in the Fuel Line or Filter

Most pressure washers have a fuel filter. If you don’t have an inline filter placed between the fuel lines, you may have a joint filter that attaches to the bottom of the gas tank.

One end of the filter part threads into the fuel tank and the fuel line is attached to the other end. When the filter becomes plugged with dirt, it may no longer allow sufficient fuel to pass through the filter.

Another thing that can restrict fuel flow is a clogged fuel line. To find a clog in a fuel line, stop and start the fuel flow while checking the fuel flow coming from each section of the fuel line.

SOLUTION: To remove a restriction from the line, remove the fuel line from the pressure washer and spray some carburetor cleaner into the line to help loosen the clog. Next, blow air through the line using compressed air until the clog is removed.

Reinstall the line. If you can’t get the clog removed or you find your fuel lines are dry and cracked, you can easily replace it with a new fuel line purchased from your local hardware store.  

Check the fuel filter and replace it if dirty causing a fuel restriction.

4. Dirty Carburetor

Old varnish and deposits left behind by old fuel can clog fuel passageways preventing the right amount of gas to mix with air for combustion.

The Generac pressure washer may run sluggish and shut down when the engine is no longer able to get the air and fuel mixture it requires.

SOLUTION: Clean your carburetor to remove gummy deposits and crusty buildups that remain from running old fuel and fuels with ethanol.

If your carburetor is excessively dirty or has broken components, you may have to rebuild or replace it.

5. Wrong Choke Setting

A Generac pressure washer with a cold engine must be started with the choke closed to restrict air. Once the engine warms up the choke must be adjusted to the open position to allow more airflow so the engine continues to run.

SOLUTION: If your engine starts and then shuts down right away, you need to make sure the choke is off and in the open position.

6. Clogged Air Filter

The air filter is essential to keep dirt from entering the air intake allowing dirt to wear the engine. This is an important part that must be routinely checked to keep it in good condition.

For the average homeowner, I recommend replacing the air filter annually and cleaning it a few times a year. 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 Generac operator’s manual.

Clean a Generac pressure washer 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 Generac pressure washer 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.

7. Bad Fuel Tank Vent

The fuel tank needs to have a vent so air is able to pass through it to equalize the pressure in the fuel tank. When the vent is plugged, the tank will form a vacuum and won’t allow fuel to get to the carburetor. Your engine will stop running.

You can determine whether the fuel tank vent is your problem by testing it with a pressure gauge. If you don’t have a gauge you can try this method:

  • If the pressure washer dies and won’t start until you loosen the cap to allow air into the tank, try to replicate the problem to confirm a fuel tank vent problem.
  • Retighten the gas cap and allow the engine to run. If the engine begins to run sluggish, dies, and won’t restart until you loosen the cap, you most likely have a bad fuel tank vent.

Look for a part installed on the top of the fuel tank called the rollover vent that allows air to pass through the tank.

SOLUTION: Replace the rollover valve tank vent (ROV) when you find the fuel tank is no longer venting properly.

8. Dirty Spark Plug

The spark plug provided the spark required to get it started, however, if the plug is very dirty or damaged, it may have intermittent spark problems that will cause the pressure washer to sputter and die.

SOLUTION: Remove the spark plug and check its condition. If the tip is very dark in color, the electrode is worn or the porcelain is broken, you must replace the spark plug with a new one.

If it appears in good condition, clean it with a wire brush and check the electrode gap and securely attach the spark plug wire. A loose wire or incorrect spark plug gap can also cause the pressure washer to quit running.

9. 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.

10. Insufficient Engine Oil Level

Your pressure washer may be running for a while and then suddenly stop. Check to see if the low engine oil light is on.

When the oil level is low, Generac has a sensor that will shut the engine down to protect it from damage. It will not restart until the engine oil level is corrected.

Continuing to run an engine that is low on oil can result in significant engine damage because a lack of sufficient lubrication will cause friction to build in the engine. The engine can become so hot that the parts can begin to melt.

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.

11. Engine 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 chainsaw to a small engine mechanic, Generac service center, or engine dealer for testing and making necessary repairs.