Toro Weed Trimmer Model 51956 Repair Manual

The Toro Weed Trimmer Model 51956 is a gas-powered string trimmer designed for residential lawn and garden maintenance. This manual provides comprehensive repair, maintenance, and troubleshooting information for the trimmer's engine, cutting head, fuel system, ignition, and drive components. Below are key sections covering safety, specifications, disassembly, common repairs, parts identification, and maintenance procedures.

1. Features at a Glance 2. Safety Precautions 3. Specifications 4. Tools Required 5. Parts Identification 6. Engine Repair 7. Cutting Head Repair 8. Fuel System Service 9. Ignition System 10. Drive Shaft & Gearbox 11. Maintenance Schedule 12. Troubleshooting

Features at a Glance

Key components: 2-cycle gasoline engine, bump-feed cutting head, straight shaft, anti-vibration handle, manual starter, adjustable shoulder strap, and debris shield.

Feature	Description
Engine Type	2-cycle, air-cooled, single cylinder
Displacement	25.4 cc (1.55 cu in)
Fuel Mix	Gasoline and 2-cycle oil (50:1 ratio)
Cutting Swath	16 inches
Cutting Line	0.095 inch diameter
Shaft Type	Straight steel drive shaft
Starter	Recoil pull-start
Weight	Approx. 10.5 lbs (4.8 kg)
Vibration Damping	Anti-vibration handle system
Warranty	2-year limited

Safety Precautions

Always follow safety guidelines to prevent injury or damage.

Disconnect spark plug wire before any repair.
Allow engine to cool completely before servicing.
Work in a well-ventilated area away from ignition sources.
Wear safety glasses, gloves, and sturdy footwear.
Use only Toro-approved replacement parts.

WARNING! Gasoline is flammable. Do not smoke or work near open flames. Ensure trimmer is on a stable surface during repair.

Specifications

Model: 51956
Engine: 2-cycle, 25.4 cc
Power Output: 0.8 kW (1.1 hp) at 7000 rpm
Fuel Tank Capacity: 14.8 fl oz (0.44 L)
Oil Tank Capacity: Integrated fuel mix
Idle Speed: 2800–3200 rpm
Cutting Line Length: Up to 12 ft of 0.095" line
Drive System: Flexible steel shaft to gear head
Gear Ratio: 1:1 (direct drive)
Sound Level: 96 dB(A) at operator's ear
Emissions: Meets EPA Phase 2 standards

Tools Required

Basic tools needed for most repairs:

Socket set (8mm, 10mm, 13mm)
Screwdrivers (flathead, Phillips #2)
Needle-nose pliers
Spark plug wrench (13/16")
Carburetor adjustment tool
Torx T20/T25 drivers
Compressed air (for cleaning)
Feeler gauge (0.020" for spark plug gap)

Parts Identification

Major components and part numbers (example):

Component	Part Number	Description
Engine Assembly	51956-01	Complete 2-cycle powerhead
Carburetor	51956-12	Diaphragm type, adjustable H/L
Ignition Coil	51956-23	Electronic, with kill switch
Fuel Tank	51956-31	Polyethylene, 14.8 oz
Cutting Head	51956-45	Bump-feed, dual line
Drive Shaft	51956-52	Flexible steel, 48" length
Gearbox	51956-67	Bevel gear, grease lubricated
Spark Plug	Champion RCJ-6Y	Gap 0.020"
Air Filter	51956-78	Foam element
Recoil Starter	51956-84	Pull-start assembly

Engine Repair

Common engine repairs and procedures.

Spark Plug Replacement: Remove wire, clean area, unscrew plug, gap new plug to 0.020", install hand-tight then 1/4 turn with wrench.
Carburetor Adjustment: Locate H (high) and L (low) screws. Initial setting: 1-1/4 turns out from lightly seated. Fine-tune at operating temperature.
Air Filter Service: Remove cover, wash foam filter in soapy water, dry, apply light oil, reinstall.
Muffler Cleaning: Remove muffler bolts, clean carbon deposits with wire brush, check gasket, reinstall.
Cylinder Inspection: Remove spark plug, inspect cylinder through hole for scoring or damage.

CAUTION! Do not overtighten spark plug. Ensure carburetor screws are not turned beyond factory limits.

Cutting Head Repair

Bump-feed head maintenance and line replacement.

Remove spool: Press tabs on head cover, lift off spool.
Clean debris: Wash spool and housing with water, dry thoroughly.
Reload line: Cut two 6-ft lengths of 0.095" line. Insert ends into spool holes, wind evenly in direction of arrows.
Reassemble: Thread lines through eyelets, snap spool back into housing.
Test feed: Bump head on ground while running at low speed to advance line.

Tip: Soak trimmer line in water for 24 hours before use to increase flexibility and durability.

Fuel System Service

Fuel tank, lines, and filter maintenance.

Drain old fuel: Use siphon or tilt trimmer into approved container.
Replace fuel filter: Disconnect fuel line from carburetor, pull filter from tank, install new filter.
Inspect fuel lines: Check for cracks, stiffness, or leaks. Replace if damaged.
Clean fuel tank: Remove tank, rinse with fresh gasoline, dry completely.
Reassemble: Connect lines, ensure clamps are secure.

WARNING! Use only fresh gasoline mixed with 2-cycle oil (50:1). Stale fuel can cause starting and performance issues.

Ignition System

Testing and replacing ignition components.

Spark Test: Remove spark plug, reconnect wire, hold plug base against cylinder head, pull starter. Look for bright blue spark.
Ignition Coil: If no spark, check coil air gap (0.010"–0.012"). Adjust by loosening mounting screws.
Kill Switch: Test continuity; replace if circuit is always open or closed.
Wiring: Inspect for frayed or disconnected wires, especially near handle and engine.

Drive Shaft & Gearbox

Drive system disassembly and lubrication.

Remove cutting head: Unscrew retaining nut (left-hand thread).
Separate shaft: Remove bolts at gearbox housing, detach shaft from engine.
Inspect shaft: Check for kinks or damage. Rotate to ensure smooth operation.
Gearbox service: Remove cover, clean old grease, pack with high-temperature gear grease (NLGI #2).
Reassemble: Ensure shaft is fully engaged, tighten bolts evenly.

Note: Grease gearbox every 50 hours of operation or annually.

Maintenance Schedule

Interval	Task
Before each use	Check fuel level, inspect for loose parts, test starter
Every 10 hours	Clean air filter, check spark plug, inspect cutting head
Every 25 hours	Replace spark plug, clean fuel filter, check carburetor settings
Every 50 hours	Grease gearbox, inspect drive shaft, replace fuel lines
End of season	Drain fuel, run carburetor dry, clean entire unit, store indoors

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Old fuel, clogged filter, no spark	Use fresh fuel mix, replace filter, check spark plug and coil gap.
Engine starts then dies	Dirty carburetor, air leak, fuel line issue	Clean carburetor, inspect gaskets, replace fuel lines.
Loss of power	Clogged air filter, exhaust port carbon	Clean/replace air filter, decarbonize muffler and exhaust port.
Excessive vibration	Bent drive shaft, loose parts	Inspect shaft, tighten all bolts and handle screws.
Line not feeding	Tangled spool, worn eyelets	Reload spool evenly, replace worn cutting head components.
Overheating	Lean fuel mix, dirty cooling fins	Adjust carburetor richer, clean cylinder cooling fins.

Reset: For electronic ignition, disconnect spark plug wire for 1 minute to reset module.

Service Support: 1-800-348-2424; www.toro.com