Owner’s manual
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Should I use 87 or 91 gas for lawn mower?
For the Craftsman rotary lawn mower model 917379100, use 87-octane (regular) unleaded gasoline for normal mowing. Higher octane (like 91) does not add power or “clean” the engine; it mainly resists knock in high-compression engines, which most walk-behind mowers are not.
What to use (and what to avoid)
- Use fresh 87-octane unleaded from a busy station.
- Use ethanol-free gas when available; it stores better and reduces fuel-system issues.
- If you must use E10 (10% ethanol), keep it fresh and do not store it long-term.
- Avoid E15/E85 fuels; they can cause hard starting and fuel-system damage.
- Do not mix in additives “to raise octane”; it is unnecessary for this mower.
Quick comparison: 87 vs 91 in a walk-behind mower
| Fuel choice | What you get | Best use case |
|---|---|---|
| 87 octane | Correct performance for most mower engines | Everyday mowing |
| 91 octane | No added power; higher cost | Only if 87 is unavailable |
Why it matters
Using the right fuel helps prevent common problems like hard starting, surging, and carburetor varnish. Most “fuel issues” on walk-behind mowers come from old gas, not from octane being too low.
Tips to prevent fuel problems
- Buy only what you will use in 30 days.
- Let the engine cool before refueling.
- For storage, run the mower dry or treat fuel with stabilizer per the 917379100 owner's manual.
- If the mower sits for months, drain the tank and carburetor bowl (if equipped) before the next season.
Related DIY help
Last updated: January 2026
What are the most common issues with 917379100?
On the Craftsman 917379100 rotary lawn mower, the most common problems we see are no-start or rough running, poor cut quality, self-propel/drive issues, and control cable problems. These usually trace back to routine wear items (blade, belt, cables) or basic fuel and maintenance needs.
Most common symptoms and what they usually point to
- Won’t start or starts then dies: old fuel, dirty carburetor, fouled spark plug, clogged air filter, or a stuck safety control.
- Runs rough or surges: restricted fuel flow, dirty carburetor passages, or partially clogged air filter.
- Cuts unevenly or leaves strips: dull/bent blade, loose blade hardware, or deck buildup.
- Vibration: damaged blade, missing/loose blade adapter, or debris wrapped around the blade area.
- Self-propel won’t pull: worn or stretched drive belt, worn drive gears, or a slipping drive cover.
- Bail or throttle feels wrong: stretched, kinked, or broken control cable.
Quick checks we recommend first
Use the safety and adjustment steps in the 917379100 owner’s manual and then work through these basics:
- Drain and replace old gas; use fresh fuel.
- Inspect the blade for bends, cracks, and dull edges.
- Check the drive system for a loose or glazed belt.
- Confirm the engine zone control and throttle move freely and return properly.
- Clean packed grass from under the deck (with the spark plug wire disconnected).
Parts that commonly solve these issues (when worn)
| Problem area | Common wear part | Example part for this model |
|---|---|---|
| Poor cut, vibration | Blade and mounting components | Lawn mower blade 532406713, lawn mower blade adapter 532418373 |
| No/weak self-propel | Drive belt and drive components | Belt 532157769, drive cover 583720801 |
| Control problems | Cables and handle controls | Lawn mower engine zone control cable 532184588, lawn mower throttle cable 532168552 |
Why it matters
Addressing these issues early prevents bigger failures, improves cut quality, and reduces vibration that can damage the crankshaft, deck, and drive components over time.
Last updated: March 2026
What model number is the Craftsman 917379100?
The model number for this Craftsman walk-behind mower is 917379100. You’ll typically find it on the mower’s model and serial number label; matching that number ensures you get the right parts, diagrams, and maintenance instructions for your exact rotary lawn mower.
Where to find the model number on the mower
Most Craftsman walk-behind mowers place the model/serial label in one of these spots:
- On the rear of the mower deck (near the discharge opening)
- On the top of the deck, behind the engine
- Near the rear wheel height adjuster area
- On the handle bracket or handle support
- Under the rear flap (on some deck designs)
If the label is dirty or faded, wipe the deck clean and use a flashlight to read the stamped or printed characters.
Why matching the model number matters
Using 917379100 helps us match the correct parts list and diagrams for your mower, so you avoid ordering look-alike items that do not fit.
Common parts that are model-sensitive include:
- Drive belt and self-propel components
- Blade and blade adapter
- Control cables (zone control, throttle)
- Wheels and height adjusters
- Fasteners and deck hardware
Quick parts examples for model 917379100
Here are a few parts commonly replaced on this model:
| What you’re fixing | Example part for this model | What it affects |
|---|---|---|
| Poor cut quality or vibration | Lawn mower blade 532406713 | Cutting performance and balance |
| Self-propel not pulling | Belt 532157769 | Drive to the transmission/wheels |
| Engine won’t stay running when you release the handle | Lawn mower engine zone control cable 532184588 | Safety shutoff control |
Best reference for identification
For label location, diagrams, and model-specific part identification, use the 917379100 manual.
Why it matters: A single digit difference in a Craftsman model number can change the blade style, belt routing, or cable length, so confirming 917379100 first saves time and prevents returns.
Last updated: January 2026
