Craftsman 917388540 gas walk-behind lawn mower Parts

The model number is 917.388540 (often written without the dot as 917388540) for this Craftsman gas walk-behind lawn mower. You’ll find it printed on the mower’s model decal, and it’s also shown on the cover of the owner's manual.

Where to find the model number on the mower

Look for the model and serial number decal in these common spots:

• On the rear of the lawn mower housing (most common for this model)
• Near the rear discharge door area
• On the deck close to the handle mounting points
• On a label that also lists the serial number

What the model number helps you do

Using the exact model number 917.388540 ensures you get the right Craftsman parts and specs for items like the blade, blade adapter, and handle hardware.

You might see it written as	What it means
917.388540	The formatted model number shown in the manual
917388540	The same model number without punctuation (common online)

Why it matters

Craftsman model numbers can look similar across different walk-behind mowers. Matching 917.388540 exactly prevents ordering the wrong blade, belt, or fasteners and helps you follow the correct maintenance and safety instructions.

Last updated: February 2026

For the Craftsman 917388540 gas walk-behind lawn mower, use fresh, clean regular unleaded gasoline with a minimum of 87 octane. Using 89 octane will not improve performance in normal mowing; the key is using fresh fuel and avoiding higher-than-recommended ethanol blends (and not mixing oil into the gas). See the fuel guidance in the owner's manual.

What to use (and what to avoid)

• Use 87 octane (regular unleaded) or higher.
• Use fresh fuel you will burn within about 30 days.
• Keep ethanol content at E10 or less (typical pump gas); avoid higher-ethanol fuels.
• Do not mix oil with gasoline (this mower uses separate crankcase oil).
• Wipe up spills and refuel only when the engine is off and cooled.

Quick comparison: 87 vs 89

Fuel choice	Works in model 917388540?	When it makes sense	What matters more than octane
87 octane (regular)	Yes (recommended minimum)	Everyday mowing	Freshness, clean storage, E10 or less
89 octane (mid-grade)	Yes	Only if 87 is unavailable	Freshness, clean storage, E10 or less

Why it matters

Using the correct fuel helps prevent hard starting, rough running, and carburetor issues caused by stale fuel or moisture-related fuel breakdown during storage. Octane is rarely the problem on walk-behind mower engines; fuel freshness and proper storage are what protect performance.

Helpful fuel and storage tips

• Fill the tank to the bottom of the filler neck; do not overfill.
• If the mower will sit 30 days or longer, run the engine until the fuel system is empty (per the manual’s storage guidance).
• Store gasoline in an approved container, tightly sealed, away from heat sources.
• If you are also doing seasonal maintenance, follow the oil-change interval and tune-up steps in the owner's manual.

Last updated: February 2026

Craftsman model 917388540 is identified by its model number, not by a built-in “year” code. To determine the year, we use the serial number on the rear housing decal and match it to the date-of-purchase information and the identification guidance in the 917388540 owner's manual.

Where to find the information you need

You can pin down the year quickly using the mower’s identification decal.

• Look for the model and serial number decal on the rear of the lawn mower housing.
• Write down the serial number exactly as shown.
• Record the date of purchase if you still have a receipt or service record.
• Use the identification and record-keeping section in the 917388540 owner's manual.
• If the decal is damaged, clean the area gently and use a flashlight to read stamped or printed characters.

How “model number” and “serial number” differ

The model number tells us the product family and configuration; the serial number is what ties to manufacturing timing.

Identifier	What it tells us	Where to find it	Used for
Model number (917388540)	Which Craftsman mower you have	Rear housing decal	Correct parts diagrams and part compatibility
Serial number	Production tracking info	Rear housing decal	Determining build timing and verifying exact configuration
Date of purchase	When it was bought	Receipt or your records	Warranty timing and maintenance history

Why it matters

Knowing the correct year (or at least the correct serial number range) helps us match the right Craftsman walk-behind mower parts and specs, such as blade hardware torque and the correct blade adapter and fasteners.

Parts that commonly depend on correct identification

These are examples of items where exact fit matters:

• Lawn mower blade adapter 532418373
• Belt, 21-in 532406712
• Husqvarna lawn mower rear skirt 532413160
• Grass bag 532410666

Last updated: February 2026