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.
- 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.
| 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 |
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.
- 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.
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.
- 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.
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).
| 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 |
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.
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.
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
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 |
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





