Craftsman 917378644 gas walk-behind lawn mower Parts

Yes. For Craftsman model 917378644, use unleaded regular gasoline in the fuel tank; do not mix oil into the gas (this mower uses a 4-cycle engine with oil added separately). The manual lists a fuel capacity of 1.6 quarts of unleaded regular. See the 917378644 owner's manual.

• Use fresh unleaded regular gasoline.
• Do not mix 2-cycle oil into the fuel.
• Do not use old gas from last season.
• Avoid leaving fuel sitting in the mower for 30 days or longer; drain the tank and run the engine until the carburetor is empty for storage.
• Wipe up spills right away and refuel only when the engine is off and cool.

Stale fuel and moisture in fuel are common causes. We recommend these checks:

• Replace old fuel with fresh fuel.
• Inspect the air filter and spark plug condition.
• If fuel sat for storage, empty the tank and run the engine until it stops.
• Check that the operator presence control bar is held down during starting.
• If you suspect blade impact or vibration, inspect the blade and adapter; a damaged adapter can affect starting and operation.

Using the correct fuel helps prevent hard starting, rough running, and fuel-system damage during storage. Fresh unleaded regular gas, plus the right engine oil in the crankcase, keeps the 917378644 running reliably season after season.

Last updated: February 2026

The model number is 917.378644; it’s printed on the Craftsman rotary lawn mower’s identification label and shown on the cover of the 917378644 owner’s manual. This is the correct model number to use when ordering parts and looking up diagrams.

We typically see the model number on a label or plate attached to the mower housing or handle area. Check these common spots:

• Rear of the deck near the discharge door
• Top of the deck near the engine mounting area
• Handle support bracket area
• Near the height adjuster hardware
• On the owner’s manual cover and parts list pages

Craftsman walk-behind mowers can look similar across years, but parts can differ by model. Using 917.378644 helps match the correct blade, drive belt, and control cables.

We recommend confirming the model number exactly as printed (including punctuation). For this mower, the manual shows it as 917.378644, while the parts page uses 917378644; both refer to the same model.

Last updated: February 2026

On Craftsman model 917378644, a mower that starts, runs briefly, then sputters and dies is usually losing fuel flow or airflow as it warms up. The most common causes are stale fuel and a dirty carburetor, followed by a restricted air filter or a failing spark plug.

• Drain old gas and refill with fresh fuel (old fuel causes lean running and stalling).
• Make sure the choke is opening fully after starting.
• Inspect the air filter; replace it if it is dirty or oil-soaked.
• Check the spark plug condition and replace it if fouled or worn (the manual calls for seasonal or 100-hour replacement).
• Clear grass and debris from the engine area; restricted airflow can make the engine run hotter and stall.

Old fuel can leave varnish that clogs tiny carburetor passages, so the engine runs for a moment on the initial fuel, then starves.

Best next steps:

• Empty the tank and bowl (if accessible), then add fresh fuel.
• If symptoms persist, clean the carburetor thoroughly or replace it.
• Avoid repeated priming; follow the starting steps in the 917378644 owner’s manual.

The manual emphasizes keeping the engine and underside of the deck clean; heavy grass and debris can restrict airflow and load the engine.

Best next steps:

• Scrape built-up grass from the underside of the deck.
• Clean under the drive cover at least twice per season.
• Keep the top of the engine around the starter clear.

Repeated stalling is hard on the engine and can leave uncut clumps because the mower cannot maintain the FAST engine speed recommended for best bagging and cutting performance.

Last updated: February 2026