Owner’s manual
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Should I use 87 or 91 gas for lawn mower?
For the Craftsman 247372650 21-inch mulching lawn mower, use fresh unleaded gasoline; 87 octane is the right choice for normal operation. Higher octane (like 91) does not add power or improve mowing performance in this engine, so it is unnecessary.
What fuel to use (and what to avoid)
- Use fresh unleaded gasoline (the manual lists fuel capacity as 1 quart, unleaded).
- Use 87 octane for everyday mowing.
- Avoid using old gas that has been sitting from one season to the next.
- Store fuel only in an approved gas can; keep it clean and rust-free.
- Never store the mower indoors with gasoline in the tank where fumes could reach a flame or spark.
Quick comparison: 87 vs 91 octane
| Fuel choice | Best for this mower | What you will notice |
|---|---|---|
| 87 octane unleaded | Yes | Normal starting, normal power, correct everyday fuel |
| 91 octane unleaded | Not needed | No performance gain; extra cost |
Why “higher octane” is not “better” here
Octane mainly relates to resistance to knock in higher-compression engines. Most walk-behind mower engines are designed to run correctly on regular unleaded, so paying for premium fuel typically does not change how the mower runs.
Fuel handling and storage tips
- Buy gas in small quantities so it stays fresh.
- If the mower will sit for an extended period, follow the storage steps in the 247372650 owner’s manual.
- Keep the engine area clean (grass and debris buildup increases fire risk).
Why it matters
Using the correct fuel and safe storage practices helps prevent hard starting, rough running, and fuel-system issues, and it reduces fire hazards during storage.
Last updated: January 2026
What model number is the Craftsman 247372650?
The model number for this Craftsman 21-inch mulching lawn mower is 247.372650 (often written without the dot as 247372650). You’ll find it on the model/serial label attached to the top rear of the mower deck; confirm it there before ordering parts.
Where to find the model number on the mower
Check these common spots on Craftsman walk-behind mowers like model 247372650:
- Top rear of the mower deck (primary model/serial label location)
- Near the rear discharge area, just above the deck edge
- On a label that may be partially covered by grass buildup (clean the area first)
For diagrams and label location details, use the 247372650 owner's manual.
Model number vs. engine model number
This mower has two different identifiers; both matter when ordering the right items.
| What you’re identifying | What it’s used for | Where it’s found |
|---|---|---|
| Mower model number: 247.372650 | Mower parts like blade, wheels, drive parts | Label on top rear of deck |
| Engine model number: 143.434132 | Engine-specific parts like spark plug, carburetor items | On the engine blower housing near the spark plug |
Why it matters
Using the exact mower model number helps us match the correct repair parts list and diagrams for your deck size and drive system. Using the engine model number helps match tune-up and engine components that can vary even on the same mower platform.
Last updated: January 2026
Where is Craftsman's model number?
On the Craftsman 247372650 21-inch mulching lawn mower, the model number is on the mower’s model tag or decal on the deck or handle area. The engine also has its own separate model and serial identification stamped on the engine housing; both are useful when ordering parts.
Where to look on the mower (247372650)
Check these common spots first:
- Top of the mower deck near the rear discharge area
- Side of the deck near a rear wheel
- Handle bracket area where the handle bolts to the deck
- Under the rear flap or near the height adjuster hardware
Where to look on the engine (separate from the mower model)
Your mower can be model 247372650, while the engine can have a different model number. In the manual’s engine section, the engine identification is shown as MODEL and SERIAL numbers on the engine itself.
Typical engine ID locations:
- Stamped into the blower housing or recoil starter housing
- On a metal tag or decal near the muffler or fuel tank
- On the valve cover area (varies by engine family)
Mower model vs. engine model: what to use
Use this quick guide when searching parts.
| What you’re fixing | Use this ID first | Why |
|---|---|---|
| Deck, wheels, handle, chute, drive system | Mower model 247372650 | These parts are tied to the mower chassis |
| Carburetor, recoil starter, muffler, air cleaner | Engine model and serial | Engine parts are matched to the engine build |
Why it matters
Using the correct identification prevents ordering the wrong blade, drive belt, or engine parts. It also helps match hardware like a wing nut or cotter pin to the correct diagram callout.
Helpful references
- Use the diagrams and identification notes in the 247372650 owner’s manual.
Last updated: January 2026
