Owner’s manual
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Should I use 87 or 91 gas for lawn mower?
For the Craftsman rotary lawn mower model 917377590, use 87-octane (regular) unleaded gasoline for normal operation. Higher octane (like 91) is not required for performance; the bigger priority is using fresh, clean fuel and storing it safely as outlined in the 917377590 owner's manual.
What to use (and what to avoid)
- Use fresh 87-octane unleaded from a clean gas can.
- Avoid stale fuel; it is a common cause of a mower that “does not start.”
- Keep fuel free of water, rust, and dirt (replace a rusting gas can).
- Do not fill the tank indoors or when the engine is hot; let the engine cool first.
- Clean up spilled gasoline before starting the engine.
Quick guidance by situation
| Situation | Best choice | Why |
|---|---|---|
| Normal mowing | 87 octane | Meets typical small-engine needs without extra cost |
| First start after storage | Fresh 87 octane | Reduces hard-start and rough-run issues tied to stale fuel |
| Repeated no-start or surging | Drain old fuel; refill with fresh 87 | Old fuel and contamination are frequent root causes |
Why it matters
Most “fuel problems” on walk-behind mowers are not caused by octane rating; they are caused by fuel quality and age. The manual’s troubleshooting guidance points to stale fuel and water in fuel as common reasons the engine will not start, so keeping gasoline fresh does more than switching from 87 to 91.
Related maintenance tip
If you are also servicing the cutting system, follow safe blade-handling steps and use the right tools; our how to sharpen a lawn mower blade guide pairs well with the maintenance schedule in your manual.
Last updated: January 2026
What are the most common issues with 917377590?
The most common problems we see on the Craftsman 917377590 rotary lawn mower involve poor cutting performance, self-propel drive issues, and starting or shutoff control problems. These typically trace back to normal wear items like the blade, drive belt, wheels/gears, or the engine zone control cable; use the owner's manual for model-specific adjustments and safety steps.
Common symptoms and what usually causes them
- Cuts unevenly or leaves strips: dull/bent blade, loose blade hardware, worn blade adapter, deck buildup
- Vibration or rattling: damaged blade, worn blade adapter, loose fasteners
- Self-propelled mower will not move or slips: worn/stretched drive belt, worn drive gears/pinion, wheel wear
- Hard to start or starts then dies: stale fuel, dirty air filter, fouled spark plug, carburetor varnish (common after storage)
- Engine will not keep running when you release the handle: misadjusted or damaged zone control cable
Quick checks we recommend first
- Disconnect the spark plug wire before inspecting under the deck.
- Tip the mower with the air filter and carburetor side up to reduce fuel/oil leakage.
- Inspect the blade and mounting stack; replace worn parts as needed.
- Check the drive system for belt wear and debris under the drive cover.
- Confirm the control cable moves freely and returns fully.
Parts that commonly fix these issues (for model 917377590)
| Symptom | Part to inspect/replace | What it does |
|---|---|---|
| Poor cut, vibration | Lawn mower mulching blade 532406713 | Provides the cutting edge; damage causes poor cut and vibration |
| Blade won’t stay tight, wobble | Lawn mower blade adapter 581547901 | Centers and drives the blade on the crankshaft |
| Self-propel weak/no drive | Belt 532157769 | Transfers power to the drive system |
| Won’t roll smoothly, drive slips | Lawn mower wheel 532180552 | Worn wheel surfaces/gearing reduce traction and drive |
| Shuts off or won’t stay running with handle held | Lawn mower engine zone control cable 582991501 | Controls engine run/stop via the operator presence control |
Why it matters
Catching blade and drive wear early protects the crankshaft, improves cut quality, and prevents sudden loss of self-propel function during mowing.
Last updated: March 2026
What model number is the Craftsman 917377590?
The model number for this Craftsman walk-behind rotary lawn mower is 917.377590 (often written without the dot as 917377590). You’ll see it printed on the mower’s model label and on the cover of the 917377590 owner's manual.
Where to find the model number on the mower
Check these common locations on Craftsman walk-behind mowers:
- On the rear of the deck near the discharge opening
- On the top of the deck near the engine mounting area
- Near the handle mounting brackets
- On a label or plate that also lists serial information
If the label is dirty or faded, wipe it with a damp rag and mild cleaner so the digits are readable.
Model number vs. engine model number (they are different)
Your mower has its own model number, and the engine has a separate model number used for engine-specific parts.
| Item | What it identifies | Example from documentation |
|---|---|---|
| Mower model number | The Craftsman mower (deck, drive, wheels, handle) | 917.377590 |
| Engine model number | The engine itself (carburetor, recoil starter, ignition) | 143.986700 |
Why it matters
Using the correct model number helps us match the right repair parts and diagrams for your exact mower, especially for items like the drive system, blade, and height adjusters.
If you’re replacing cutting parts, match the mower model first, then confirm the blade style; for this model, a common replacement is the lawn mower mulching blade 532406713.
Last updated: January 2026
