Craftsman 358791040 trimmer Parts

For the Craftsman 358791040 gas line trimmer, we use a 40:1 fuel mix: 3.2 oz of synthetic 2-cycle air-cooled engine oil per 1 gallon of unleaded gasoline. Mix it in an approved fuel container and shake briefly so the oil and gas blend evenly; see the 358791040 operator's manual.

How to mix it correctly

• Use fresh, unleaded gasoline.
• Use synthetic 2-cycle oil made for air-cooled engines.
• Measure 3.2 oz oil for every 1 gallon gas.
• Add oil to the gas can, then add gasoline.
• Cap and shake the container momentarily to fully mix.

What not to use (to avoid engine damage)

The 358791040 manual specifically warns against these oils:

• Automotive (4-cycle) engine oil
• Marine 2-cycle oil
• Old fuel that has been sitting long enough to separate or degrade

Quick mix ratio table

Gasoline amount	40:1 oil amount	Notes
1 gallon	3.2 oz	Standard mix for this model
1/2 gallon	1.6 oz	Useful for small batches
1 quart	0.8 oz	Good for testing after storage

Why it matters

A correct 40:1 mix keeps the 2-cycle engine properly lubricated. Too little oil can score the piston and cylinder; too much oil can cause heavy smoke, plug fouling, and poor throttle response.

Last updated: January 2026

To unflood a Craftsman 358791040 gas line trimmer, stop trying to start it, open the choke, hold the throttle wide open, and pull the starter until it fires; then let it warm up at a lower throttle. Follow the starting and safety guidance in the 358791040 owner's manual.

Quick unflood steps (works for most 2-cycle trimmers)

• Move the ON/OFF switch to ON.
• Set the choke to RUN/OFF (choke open), not FULL CHOKE.
• Hold the throttle trigger wide open.
• Pull the starter rope 5 to 10 times until the engine sputters or starts.
• As soon as it starts, feather the throttle and let it warm up; avoid revving hard right away.
• If it still will not start, remove and dry the spark plug, then try again.

What to check if it keeps flooding

Flooding usually happens from too much priming, too much choke time, or a fuel delivery issue.

• Primer bulb: If it is cracked or will not firm up, replace the ayp lawn & garden equipment engine carburetor primer bulb 530047721.
• Fuel lines: A split or loose line can pull air and cause repeated hard-starting and over-priming; inspect and replace the ayp lawn & garden equipment fuel line, large 530069216 if it is soft, swollen, or leaking.
• Air filter: A clogged filter can make the mixture too rich; clean it on schedule.
• Fuel: Use fresh, properly mixed 2-cycle fuel; old fuel makes starting harder and leads to over-choking.

Safety and setup that matters while you’re pulling it over

The manual emphasizes safe handling around the cutting head and muffler.

• Keep the cutting attachment off the ground while starting/adjusting.
• Hold the unit firmly with both hands.
• Keep the trimmer head below waist level.
• Stay clear of the spinning line and hot muffler.

Symptom-to-fix guide

What you notice	Most likely cause	What we do first
Strong fuel smell, wet plug	Flooded engine	Choke open, throttle wide open, pull to clear
Starts then dies unless choked	Lean fuel delivery	Check fuel line, fuel filter, primer bulb
Head spins at idle after it starts	Idle set too high	Adjust idle so head does not move

Why it matters

Clearing a flooded engine the right way prevents spark plug fouling, reduces wear on the recoil starter, and helps you avoid unsafe starts where the trimmer head spins unexpectedly at idle.

Last updated: January 2026

To replace the cutting line on your Craftsman gas trimmer model 358791040, we remove the old line and line glide plate, clean the cutting head, reinstall the line glide plate, then feed a new line through the correct holes so both ends are the same length. Follow the hole and arrow guidance in the 358791040 owner's manual.

Safety first

Before any maintenance on the 358791040, we stop the unit and disconnect the spark plug wire so the trimmer head cannot spin unexpectedly.

• Stop the engine and let moving parts fully stop
• Disconnect the spark plug boot before servicing
• Wear gloves and eye protection
• Use only Craftsman replacement line (never wire, rope, or string)
• Replace cracked or damaged trimmer head parts before use

Step-by-step: replace the trimmer line

These steps match the manual’s line replacement procedure for this Craftsman trimmer.

• Remove the old line and remove the line glide plate from the cutting head
• Clean the entire surface of the cutting head (dirt here causes poor feeding)
• Reinstall the line glide plate before installing new line
• Identify the correct line holes using the line glide plate directions
• Insert both ends of the new line through the proper holes in the side of the cutting head
• Pull the line so it seats against the hub and extends fully through the positioning tunnels
• Confirm both ends are the same length (even lengths reduce tangling and vibration)

Line selection tips (what the colors mean)

The manual calls out line type by color; choose based on what you cut most often.

Line type	Best for	Typical result
Red line	Grass and small weeds	Cleaner cut, less load on engine
Black line	Larger weeds and light brush	More durability, slightly more drag

Why it matters

Correct line routing and equal line length help the trimmer head feed smoothly, reduce tangles, and keep vibration down. Keeping the line glide plate installed and aligned also prevents premature wear on the cutting head.

Last updated: January 2026