Owner’s manual
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Should I use 87 or 91 gas for lawn mower?
For the Craftsman 917378040 22-inch rotary lawn mower, we recommend regular 87-octane gasoline; higher octane (like 91) does not improve performance in small mower engines. Use fresh fuel and follow the ethanol limit in the 917378040 owner's manual to protect the fuel system.
Fuel type that works best
Use gasoline that matches these basics:
- 87 octane (regular unleaded) for normal mowing
- Up to 10% ethanol (E10) maximum; higher ethanol blends can cause fuel-system problems and can void the warranty
- Fresh fuel; avoid storing gas from one season to the next
- Clean gas can; replace rusty cans to prevent dirt and rust from entering the carburetor
87 vs 91: what changes (and what does not)
Higher octane is mainly for engines designed for higher compression. Most walk-behind mower engines are tuned for regular fuel.
| Fuel choice | What you can expect | Best use case |
|---|---|---|
| 87 octane | Normal starting and power | Everyday mowing |
| 91 octane | No added power in this mower | Only if 91 is the only fresh fuel available |
If the mower will sit for 30 days or more
Old fuel is a top cause of hard starting and rough running. Our best practice is to prevent gum and varnish buildup.
- Run the mower regularly during the season
- For longer storage, empty the tank and run the engine until the fuel lines and carburetor are empty
- Store the mower only after the engine cools
Why it matters
Using the right fuel helps prevent carburetor deposits, corrosion from moisture in alcohol-blended fuels, and starting issues. It also helps your Craftsman mower maintain consistent engine speed (which is factory set for performance).
Last updated: January 2026
What model number is the Craftsman 917378040?
The model number for this Craftsman walk-behind mower is 917.378040 (often written without the dot as 917378040). You’ll see it printed on the mower’s model tag and on the cover of the 917378040 owner's manual.
Where to confirm the model number on the mower
Check these common locations on a Craftsman 22-inch rotary lawn mower:
- On the rear of the deck near the discharge opening
- On the top of the deck near the engine mounting area
- On the rear shield or rear door area (bagging side)
- On a sticker or metal plate that also lists engine details
Model number vs. engine model number
Your mower has a Briggs & Stratton engine, but the engine model/type/code is different from the mower model number.
| What you’re looking at | What it identifies | Example format |
|---|---|---|
| Mower model number | The Craftsman mower for parts diagrams and chassis parts | 917.378040 / 917378040 |
| Engine model/type/code | The Briggs & Stratton engine for engine-specific parts | Model-Type-Code |
Why it matters for parts lookup
Using the exact mower model number helps us match the correct diagrams and parts for your deck, drive system, and controls.
- Blade and blade hardware vary by deck and adapter style
- Drive parts (belt, pulley, transmission) vary by drive system version
- Control cables and handle parts vary by handle assembly
If you’re replacing common wear items, match parts to the 917378040 diagrams first; for example, the cable assembly 587326602 and the poulan lawn mower ground drive belt, 3/8 x 35-1/2-in 580364604 are listed for this model.
Why it matters
A single digit difference in a Craftsman model number can point to a different deck, blade adapter, or drive setup; confirming 917.378040 prevents ordering the wrong part.
Last updated: January 2026
What model number is the Craftsman 917378040?
The model number is 917.378040 (often written without the dot as 917378040). This is the model shown on the Craftsman owner’s manual for the 22-inch rotary lawn mower with a 625 Series Briggs & Stratton engine; see the 917378040 owner’s manual.
Where to confirm the model number on the mower
We recommend matching the model number on the mower’s ID label to the manual so you order the right parts.
- Check the model label on the mower deck (top or rear area of the deck)
- Check near the rear door or bagging area on many 22-inch walk-behind mowers
- Compare the label to the model printed on the manual cover
- Use the full model number when searching diagrams and parts
Common formatting you may see
The same model can appear in a few formats depending on the label or parts list.
| You might see | It means |
|---|---|
| 917.378040 | Standard manual/parts-list format |
| 917378040 | Same model number without punctuation |
| 917 378040 | Same digits with a space |
Why it matters
Craftsman model numbers are the fastest way to match the correct blade, belt, drive parts, and hardware. For example, the parts list for this mower includes a drive belt and other drive components that must match the exact model.
Last updated: January 2026
Where to find model number on Craftsman lawn mower?
On the Craftsman walk-behind mower model 917378040, we find the model and serial numbers on a decal on the rear of the lawn mower housing. This decal is the quickest way to confirm the exact model number you need for ordering parts and using the correct instructions in the 917378040 owner's manual.
Where to look on the mower
Check these common spots first (starting with the most likely for this model):
- Rear of the mower deck or housing (decal with model and serial)
- Back edge of the deck near the rear wheels
- Near the engine mounting area on the deck (sometimes a second label)
- Handle support area (less common, but worth a quick look)
What you should write down (and why)
Recording the full information helps us match the right Craftsman parts and diagrams.
| Item on decal | Example format | Why it matters |
|---|---|---|
| Model number | 917378040 | Identifies the exact mower version |
| Serial number | Varies | Helps match production changes |
| Date of purchase | Your date | Useful for maintenance records |
Tips if the decal is hard to read
If the label is dirty or faded, these steps usually make it readable enough to confirm the numbers:
- Wipe the area with a damp rag and mild soap; dry it fully
- Use a flashlight at a low angle to make embossed or faded print stand out
- Take a close-up photo and zoom in (often clearer than reading it directly)
- Copy the numbers exactly; include all digits with no spaces
Why it matters
Craftsman walk-behind mowers can use different blades, belts, and control cables across similar-looking versions. Confirming the model number from the rear housing decal helps ensure you get the correct replacement parts and service procedures.
Last updated: January 2026
