Owner’s manual
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Should I use 87 or 91 gas for lawn mower?
For the Craftsman rotary lawn mower model 917377591, we recommend using 87-octane (regular) unleaded gasoline for normal mowing. Higher octane (like 91) does not add power in small mower engines; the best results come from using fresh fuel and the correct oil level per the 917377591 owner's manual.
What to use (and what to avoid)
- Use 87-octane unleaded from a busy station (fresher fuel).
- Use fresh gas; don’t store it for long periods in the mower.
- Use a fuel stabilizer if the mower will sit more than a few weeks.
- Avoid old, sour-smelling fuel and contaminated gas cans.
- Avoid overfilling the tank; leave room for expansion.
87 vs 91: quick comparison
| Fuel choice | Best for | What you’ll notice |
|---|---|---|
| 87 octane (regular) | Everyday mowing | Normal starting and performance |
| 91 octane (premium) | Not needed for most walk-behind mowers | Usually no improvement in power or reliability |
If the mower runs rough or won’t start
Fuel quality issues often look like “bad gas” symptoms. Before replacing parts, we recommend these checks:
- Drain and replace with fresh 87-octane.
- Inspect the spark plug and air filter (common tune-up items).
- Check for water in the fuel (milky look or phase separation).
- If the mower is hard to pull or the rope sticks, follow lawn mower pull cord stuck.
Why it matters
Using the right fuel helps prevent hard starting, surging, and carburetor varnish. For model 917377591, consistent performance comes from fresh regular gas, clean airflow, and routine tune-up maintenance, not premium octane.
Last updated: January 2026
What year is Craftsman Model 917377591?
Craftsman model 917377591 is identified by its model number, not a date code; the model number alone does not reliably tell the exact year it was built. To pin down the year, we use the mower’s product ID/serial number label and the date information shown in the documentation for this model in the 917377591 owner's manual.
How to find the year on your mower
Look for the identification label on the mower (commonly on the rear of the deck, near the engine, or on the handle support). Then record the details exactly as shown.
- Find the product ID/serial number label (not just the model number)
- Write down the serial number and any date code on the label
- Note the engine brand and model (engine date codes can help)
- Compare what you find to the identification section in the 917377591 owner's manual
- If the label is damaged, take a clear photo and match characters carefully (0 vs O, 1 vs I)
Why videos about “date codes” can be misleading
Some Craftsman equipment uses a separate date code format on a label or tag, but that format is not universal across all mower types and production runs. For a walk-behind mower like the 917377591, the most dependable way to determine the year is the serial/date information on the mower’s ID label, supported by the model documentation.
Quick reference: what tells you what
| What you have | What it tells you | What to do next |
|---|---|---|
| Model number (917377591) | Which parts list and diagrams fit | Use it to look up parts and manuals |
| Serial number / product ID | Build date range and production info | Use it to determine the year |
| Engine model/type code | Engine build info (sometimes) | Use as a cross-check |
Why it matters
Knowing the correct year helps us match the right blade, drive system parts, and hardware revisions for your Craftsman rotary lawn mower. It also prevents ordering a look-alike part that does not fit your exact deck or self-propelled drive setup.
Last updated: January 2026
Where is Craftsman's model number?
On a Craftsman walk-behind mower like model 917377591, the model number is printed on the mower’s ID label (not on the engine). Once you find that label, use the full model number to match the correct deck, drive, and handle parts.
Where to look on a walk-behind mower
Check these common ID-label locations first:
- Rear of the mower deck, near the discharge chute
- Top of the deck, behind the engine (near the handle mounting area)
- Side of the deck, above a rear wheel
- Under the rear flap (near the bagging opening)
- On the handle support bracket close to the deck
For diagrams and model-specific identification notes, use the 917377591 owner's manual.
What to write down (so parts match)
Record the information exactly as shown on the label:
- Model number (example: 917377591)
- Product number or serial number (if listed)
- Any revision numbers or suffixes
- Brand name (Craftsman)
Quick guide: mower model vs. engine model
| What you’re identifying | Where it’s found | What it’s used for |
|---|---|---|
| Mower model number (917377591) | Mower deck/handle ID label | Deck, wheels, drive system, controls |
| Engine model/type/code | Engine shroud label | Engine-specific parts (carburetor, ignition, recoil) |
Why it matters
Craftsman walk-behind mowers can use different wheels, belts, and blade adapters even when they look similar. Using the exact model number helps ensure the parts diagrams match your deck and drive setup.
If you are replacing cutting components, confirm the blade style and mounting hardware; for this model, a common match is the lawn mower mulching blade 532406713.
Last updated: January 2026
