Craftsman 358791170 gas trimmer Parts

For Craftsman gas line trimmer model 358791170, the operator’s manual does not specify a single trimmer line diameter; it directs you to use Craftsman replacement line and choose the line size best suited for the job (grass and small weeds vs. larger weeds and light brush). See the 358791170 operator's manual.

What the manual says for model 358791170

In the line replacement section, the manual identifies two Craftsman line options by color and use:

• Red line (#71-85908): designed for cutting grass and small weeds
• Black line (#71-85909): designed for cutting larger weeds and light brush
• Use only trimmer line; never use wire, rope, or string

How to choose the right line (practical guidance)

Because the manual focuses on application rather than diameter, we recommend choosing based on what you cut most often:

What you’re trimming	Recommended line type (per manual)	Why it matters
Grass, light weeds	Red line (#71-85908)	Cleaner cuts with less load on the engine
Thicker weeds, light brush	Black line (#71-85909)	Better durability and less breakage

Why it matters

Using the correct line type helps your 2-cycle engine maintain RPM, reduces stalling, and limits wear on the trimmer head and line glide plate. Oversized or non-approved line can also reduce cutting performance and increase vibration.

Last updated: January 2026

Yes, TrimmerPlus-style attachments can work with the Craftsman gas trimmer model 358791170 as long as your attachment is made for a coupler-based “universal” attachment system and it locks into the coupler correctly. Our 358791170 operator's manual explains how the coupler and locking/release button must engage before use.

What to check on your 358791170 before buying an attachment

Use these quick fit checks so you do not end up with an attachment that will not lock in or will wobble:

• Confirm your trimmer has the coupler and a locking/release button (this model does).
• Make sure the attachment shaft slides fully into the coupler and the button snaps into the primary hole.
• Tighten the coupler knob securely; the attachment should not rotate or pull out.
• Use the attachment only in the primary hole unless the attachment manual specifically says otherwise.
• If the attachment will not lock, inspect the coupler area for damage or wear in the upper shaft.

Compatibility notes (what “works with Craftsman” usually means)

Many TrimmerPlus-compatible attachments are designed to fit multiple brands (including Craftsman) when the powerhead accepts that attachment style. For model 358791170, the key is the coupler connection, not the brand name printed on the attachment.

Quick compatibility table

What you have	What it should do	Result
Attachment labeled TrimmerPlus-compatible	Locks into coupler primary hole	Typically compatible
Attachment with a different shaft/coupler design	Will not lock or seats loosely	Not compatible
Attachment locks but wobbles	Indicates wear or incomplete seating	Recheck fit and coupler

Why it matters

A coupler that is not fully locked can let the attachment separate or spin unexpectedly, which can damage the drive shaft and create a safety hazard. Following the coupler locking steps in the 358791170 operator's manual helps prevent improper installation.

Last updated: January 2026

For the Craftsman 358791170 gas line trimmer, the exact fuel line inside diameter and outside diameter are not specified in the model-specific information we have; this model can use different line sizes depending on which section you’re replacing (supply vs. return) and the tank grommet/fittings. Use the 358791170 operator’s manual to confirm routing, then match the new line to the original.

How we recommend sizing the fuel line (works for this model)

• Remove the old line and cut a short sample from a straight section.
• Measure inside diameter (ID) first; that’s what must seal on the carburetor and fuel filter nipples.
• Match outside diameter (OD) so it seals tightly in the fuel tank opening/grommet.
• If the old line is swollen or brittle, size by the fitting/nipple OD instead of the old line.
• Replace both lines if one is hardened; mixed stiffness often causes air leaks.

Parts that commonly relate to fuel line service

If you’re replacing fuel line because of fuel starvation, hard starting, or cracked tubing, these model-compatible parts are often involved:

• Craftsman lawn & garden equipment engine fuel filter 530095646 (in-tank filter that can clog)
• Lawn & garden equipment engine fuel return line 530069599 (return line used on many small-engine setups)
• Primer bulb and carburetor fittings should also be inspected for leaks and loose connections

Quick symptoms guide

Symptom	Often points to	What to check
Starts then dies	Fuel restriction or air leak	Cracked line, loose fit, clogged filter
Won’t prime	Split line or bad primer circuit	Line connections, primer bulb, tank pickup
Runs only on choke	Lean condition	Air leak at line, carb adapter, fuel delivery

Why it matters

Fuel line size is critical because a slightly loose ID can pull air (lean running, stalling), and a slightly oversized OD can leak at the tank. Correct sizing helps protect the carburetor, improves starting, and prevents fuel leaks.

Last updated: January 2026

To replace the trimmer head on your Craftsman model 358791170, lock the shaft with a small screwdriver, unthread the old head clockwise (viewed from the bottom), then thread the new head on counterclockwise and tighten hand-tight only. See the 358791170 operator's manual for the exact steps.

Tools and safety prep

• Stop the engine and let it cool
• Disconnect the spark plug boot to prevent accidental starting
• Wear gloves and eye protection
• Work on a flat surface so the trimmer is stable
• Use a small screwdriver (or similar pin) to lock the shaft

Step-by-step: replacing the trimmer head (358791170)

1. Disconnect the spark plug boot.
2. Align the locking holes: rotate the arbor shaft until the hole in the dust cup lines up with the hole in the side of the gearbox.
3. Lock the shaft: insert a small screwdriver through the aligned holes.
4. Remove the old head: while holding the screwdriver in place, turn the trimmer head clockwise (looking from the bottom of the unit) to unthread it.
5. Install the new head: thread the replacement head onto the shaft counterclockwise.
6. Tighten correctly: tighten hand tight only, then remove the screwdriver.

Direction check (common confusion)

Task	Turn direction (viewed from bottom)	Why it matters
Remove old trimmer head	Clockwise	Prevents stripping threads by forcing the wrong way
Install new trimmer head	Counterclockwise	Ensures the head seats correctly on the shaft
Final tightening	Hand-tight only	Over-tightening can damage threads and make future removal difficult

Why it matters

The 358791170 uses a threaded head that can be damaged by cross-threading or over-tightening. Locking the shaft and using the correct direction helps protect the gearbox and keeps the cutting attachment secure during operation.

Last updated: January 2026

If your Craftsman gas line trimmer model 358791170 will not start, the most common causes are stale or incorrect 40:1 fuel mix, a flooded engine, or a fuel delivery/ignition issue (dirty filter, bad primer bulb, or weak spark). Use the start steps in the 358791170 operator's manual first, then check fuel and spark basics.

Quick checks (fastest fixes first)

• Confirm fresh unleaded gas mixed 40:1 with 2-cycle air-cooled oil; dump old fuel if it is more than 30 days old.
• For a cold start: press the primer bulb 6 times, set the start lever to START, then pull with a steady motion.
• If you smell fuel or the plug is wet, treat it as flooded: set start lever to RUN, hold throttle wide open, and pull until it starts.
• Make sure the ON/STOP switch is in the ON position (it resets after stopping).
• Inspect the air filter; clean it if dirty (a restricted filter can cause hard starting and poor running).

Parts that commonly cause a no-start on this model

If fuel is not reaching the carburetor or priming feels weak, these model-compatible parts are good suspects:

• Craftsman lawn & garden equipment engine fuel filter 530095646 (clogged filter blocks fuel flow)
• Ayp lawn & garden equipment engine carburetor primer bulb 530047721 (cracked bulb will not prime)
• Lawn & garden equipment engine fuel return line 530069599 (split line can pull air instead of fuel)

What to check and what it usually means

Symptom	Most likely cause	What we recommend
Primer bulb will not fill or stays collapsed	Air leak or restriction in fuel system	Check fuel lines and replace the fuel filter
Starts briefly then dies	Fuel restriction or carburetor issue	Verify fresh 40:1 mix; check filter and primer bulb
Strong fuel smell, wet plug	Flooded engine	Use flooded-start procedure (start lever RUN, throttle open)
No pop at all when pulling	Ignition/spark issue	Inspect spark plug condition and boot connection

Why it matters

A 2-cycle trimmer like the Craftsman 358791170 depends on the correct fuel mix and airtight fuel delivery. A small air leak, clogged filter, or failed primer bulb can prevent the carburetor from pulling fuel, so the engine will not fire.

Last updated: January 2026