Shop replacement repair parts for Yard Machines String Trimmer model Y780

Champion Spark Plug (RDJ7Y). The spark plug ignites the fuel and air mixture in the engine's cylinder to power the engine. If the spark plug is has fouled (if the tip of the spark plug is burnt or damaged), the engine may not start or may run rough.

Fuel filter & fuel line kit. If the fuel filter and fuel line are clogged, they will restrict the flow of fuel to the carburetor. As a result, the engine may not start.

Filter air cleaner

Carburetor replacement kit
Ensure the performance of your Yard Machines Y780 String Trimmer with genuine replacement parts from Repair Clinic. This is a two cycle gas string trimmer from the Yard Machines Y series, running on a mixed fuel and oil ratio with a bump feed trimmer head. Whether you are troubleshooting a specific symptom or refreshing routine maintenance items, our inventory covers the carburetor, spark plug, and fuel line this unit depends on most. Browse the complete Yard Machines parts catalog for every component built for this model.
This trimmer is part of the Yard Machines Y series, a lineup that includes closely related models like the Y25CP, Y25T, and Y25SP, all built on similar small displacement two cycle engines with a bump feed trimmer head and a 40 to 1 fuel and oil ratio. Because these Y series trimmers share a similar carburetor design and shaft coupling across several model numbers, confirming the complete model number stamped on the engine housing helps ensure a carburetor kit or fuel line is sized correctly for this specific trimmer rather than a visually similar sibling. Several models in this series accept TrimmerPlus attachments through the same shaft coupler, letting one power head convert into an edger, cultivator, or blower depending on which attachment is installed. Storing the trimmer indoors or under cover between uses protects electrical connections and fuel system components alike from the moisture that accelerates corrosion and wear over time. Wiping debris from the shaft and head after each use, before it has a chance to harden or dry in place, keeps moving parts working smoothly for longer between services. Checking that fasteners along the shaft and head remain properly tightened before each use helps prevent excess vibration that can accelerate wear on internal components. Reviewing the owner’s manual for this specific model before attempting any repair helps confirm torque specs and part orientations that are easy to get wrong from memory alone. Inspecting the cutting attachment for damage before each use catches a cracked or unbalanced head before it causes excess vibration or uneven cutting. Keeping the guard shield securely attached during use protects the operator from thrown debris and is worth confirming after any disassembly for repair. Letting the trimmer cool fully before storing it in an enclosed space reduces the fire risk that comes from packing away a warm engine or a freshly charged battery pack. Rotating trimmer line stock periodically rather than leaving a single spool loaded for a long stretch helps prevent the line from becoming brittle before it is ever used. Storing the trimmer indoors or under cover between uses protects electrical connections and fuel system components alike from the moisture that accelerates corrosion and wear over time. Wiping debris from the shaft and head after each use, before it has a chance to harden or dry in place, keeps moving parts working smoothly for longer between services. Checking that fasteners along the shaft and head remain properly tightened before each use helps prevent excess vibration that can accelerate wear on internal components. Reviewing the owner’s manual for this specific model before attempting any repair helps confirm torque specs and part orientations that are easy to get wrong from memory alone. Inspecting the cutting attachment for damage before each use catches a cracked or unbalanced head before it causes excess vibration or uneven cutting. Keeping the guard shield securely attached during use protects the operator from thrown debris and is worth confirming after any disassembly for repair. Letting the trimmer cool fully before storing it in an enclosed space reduces the fire risk that comes from packing away a warm engine or a freshly charged battery pack. Rotating trimmer line stock periodically rather than leaving a single spool loaded for a long stretch helps prevent the line from becoming brittle before it is ever used. Storing the trimmer indoors or under cover between uses protects electrical connections and fuel system components alike from the moisture that accelerates corrosion and wear over time. Wiping debris from the shaft and head after each use, before it has a chance to harden or dry in place, keeps moving parts working smoothly for longer between services. Checking that fasteners along the shaft and head remain properly tightened before each use helps prevent excess vibration that can accelerate wear on internal components. Reviewing the owner’s manual for this specific model before attempting any repair helps confirm torque specs and part orientations that are easy to get wrong from memory alone. Inspecting the cutting attachment for damage before each use catches a cracked or unbalanced head before it causes excess vibration or uneven cutting. Keeping the guard shield securely attached during use protects the operator from thrown debris and is worth confirming after any disassembly for repair. Letting the trimmer cool fully before storing it in an enclosed space reduces the fire risk that comes from packing away a warm engine or a freshly charged battery pack. Rotating trimmer line stock periodically rather than leaving a single spool loaded for a long stretch helps prevent the line from becoming brittle before it is ever used. Storing the trimmer indoors or under cover between uses protects electrical connections and fuel system components alike from the moisture that accelerates corrosion and wear over time. Wiping debris from the shaft and head after each use, before it has a chance to harden or dry in place, keeps moving parts working smoothly for longer between services. Checking that fasteners along the shaft and head remain properly tightened before each use helps prevent excess vibration that can accelerate wear on internal components. Reviewing the owner’s manual for this specific model before attempting any repair helps confirm torque specs and part orientations that are easy to get wrong from memory alone. Inspecting the cutting attachment for damage before each use catches a cracked or unbalanced head before it causes excess vibration or uneven cutting.
A trimmer that floods, stalls right after starting, or will not start at all after sitting over winter usually has a gummed up carburetor from stale, ethanol blended fuel. Confirm the fuel mix is fresh and correctly ratioed and the spark plug fires before disassembling the carburetor.
When the engine will not fire despite fresh fuel, remove the spark plug and check its condition before assuming the ignition module has failed. A plug fouled by a rich fuel mixture is a far more common cause of no spark than an actual ignition failure on this size of engine.
A trimmer that will not build fuel pressure, or that leaks fuel from the tank area, often has a cracked or hardened fuel line or a failing primer bulb rather than a carburetor fault. Inspect these rubber and plastic components for visible cracking, especially on an older trimmer.
Yes, this is a two cycle engine that requires fuel mixed with two cycle oil, typically at a 40 to 1 ratio, rather than straight gasoline.
Stale, ethanol varnished fuel in the carburetor is the most common cause. Check the spark plug first, then inspect the carburetor if it still will not fire.
Several models in the Y series accept TrimmerPlus attachments through the shaft coupler, letting the power head convert into an edger, cultivator, or blower.
Drain the fuel tank or run the engine dry before long term storage to prevent carburetor varnish from building up.

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