Owner’s manual
What to use to cut trimmer line?
For your Craftsman 316791890 gas line trimmer, we cut trimmer line with a sharp utility knife, heavy-duty scissors, or side cutters; then we trim it to the correct length so it does not extend past the cutting attachment shield (as described in the 316791890 owner's manual).
Best tools to cut trimmer line
Use a tool that makes a clean, square cut so the line feeds smoothly and resists fraying.
- Utility knife with a stable cutting surface (scrap wood works well)
- Heavy-duty scissors or shears (best for thinner line)
- Side cutters (diagonal cutters) for quick, clean cuts
- Lineman’s pliers (works well on thicker line)
- A dedicated trimmer line cutter (hand tool)
Quick steps (safe and consistent)
- Shut the engine off and let the cutting head stop completely.
- Put on eye protection and gloves.
- Measure and cut two equal lengths (most heads require equal lengths on both sides).
- Install the line and pull it through so both ends match in length.
Safety reminders we follow
The manual stresses safe operation and proper guarding.
- Keep the cutting attachment shield installed while operating
- Do not run the trimmer with missing or improperly installed line
- Do not extend line beyond the shield’s allowed length
What “correct length” means
Your trimmer’s shield and line cutting blade are designed to limit line length automatically during use. We still start with equal lengths so the head runs smoothly.
| If your cut is… | What you’ll notice | What to do |
|---|---|---|
| Too long | Excess vibration, line slaps shield, poor control | Recut shorter; don’t exceed shield limit |
| Uneven | Vibration, uneven cutting | Recut to equal lengths |
| Frayed/melted | Feeding issues, rapid breakage | Recut with a sharper tool |
Why it matters
A clean cut and correct length reduce vibration, help the clutch and cutting head run smoothly, and prevent the line from overextending past the shield, which improves safety and trimming performance.
Last updated: February 2026
How to replace line on Craftsman gas trimmer?
To replace the cutting line on your Craftsman gas line trimmer model 316791890, you remove the trimmer head cap, load new line into the spool (or wind it into the head, depending on the head style), then reinstall the cap and confirm the line feeds smoothly when you bump the head. For safety, stop the engine and disconnect the spark plug first; see the 316791890 owner's manual.
Before you start (safety and setup)
- Turn the engine OFF and let hot parts cool.
- Disconnect the spark plug wire before any maintenance.
- Work on a flat surface; keep the cutting attachment shield installed.
- Keep bystanders at least 50 feet away when you test-run.
Steps to replace the trimmer line (typical bump-feed head)
- Stop the engine and disconnect the spark plug wire.
- Clean grass and debris from the cutting head and shield.
- Press the head’s tabs (or unscrew the cap/knob) to remove the cap.
- Remove the spool; note how the old line is routed.
- Cut two equal lengths of trimmer line (most heads use two lines).
- Feed each line end into its eyelet or anchor slot; wind the spool in the direction of the arrow.
- Reinstall the spool and cap; pull both line ends to confirm they move freely.
- Reconnect the spark plug wire; start the trimmer and bump the head to verify feeding.
Quick checks if the line will not feed
- Line is wound the wrong direction.
- Line is too thick for the head.
- Spool is overfilled or line is crossed.
- Debris is packed inside the head.
What to inspect while you are there
| Symptom | What to check | Common fix |
|---|---|---|
| Line breaks constantly | Line cutting blade condition | Replace the blade if nicked or dull |
| Head binds in grass | Wrapped vegetation | Clean head and shield |
| Poor cutting, heavy vibration | Shield or head damage | Replace damaged parts before use |
Why it matters
Correctly loaded line reduces tangles, improves bump-feed performance, and helps prevent overheating from running the engine faster than needed for trimming.
If you need replacement components for the cutting system, you can order parts for model 316791890 from the parts list for this model, or search by model number on Sears PartsDirect.
Last updated: February 2026
What size is the fuel line on a Craftsman trimmer?
For Craftsman gas line trimmer model 316791890, fuel line size is matched by inside diameter (ID) and outside diameter (OD) to fit the tank grommet and carburetor/primer fittings. Use the original line as your sizing reference and confirm routing in the 316791890 owner's manual.
How to measure the correct fuel line size
Measure the old line before you remove it (or cut a short straight section to measure).
- Measure OD with a caliper; this controls how it seals in the tank grommet
- Measure ID with a caliper or drill-bit gauge; this controls how it grips barbed fittings
- Check whether your trimmer uses two lines (supply and return) with different sizes
- Compare length and routing so the pickup filter can reach the bottom of the tank
- Replace any line that is stiff, cracked, swollen, or gummy
Typical sizes you will see on 2-cycle trimmers
Many 2-cycle line trimmers use small fuel tubing in common ranges; your exact fit depends on the fittings and grommet on your 316791890.
| Fuel line location | Typical ID range | Typical OD range |
|---|---|---|
| Tank to carburetor (supply) | 3/32 in to 1/8 in | 3/16 in to 1/4 in |
| Primer return line | 1/8 in | 3/16 in to 1/4 in |
Model-matched replacement option
If you prefer an OEM-style replacement instead of bulk tubing, we list a compatible fuel line for this model:
Why it matters
A fuel line that is even slightly off-size can leak or pull air. That causes hard starting, needing choke longer than normal, surging, or stalling when you squeeze the throttle.
Buying parts
You can order model-matched parts for Craftsman 316791890 from the parts list for this model, or search by model number on Sears PartsDirect.
Last updated: February 2026
