CRAFTSMAN 917.379120 Service Manual
The CRAFTSMAN 917.379120 service manual provides a comprehensive reference for understanding the machine’s intended use, common failure modes, and general maintenance practices. This section focuses on establishing a solid foundation for safe operation and reliable servicing. It is essential to recognize the unit’s designed purpose, the interfaces exposed during routine maintenance, and the limitations that affect diagnostics and repair. A clear appreciation of these factors helps technicians approach repairs methodically and minimizes the risk of introducing new issues during service. Proper documentation and adherence to the outlined procedures support consistent performance and longer service life for the equipment.
Safety warnings are an integral part of any service workflow. The manual emphasizes the priority of preventing injuries by identifying hazards such as fuel exposure, rotating blades, hot engine components, and moving lines or belts. Before any maintenance, the operator should disconnect the spark plug lead, allow the engine to cool, and perform a visual inspection for damaged wiring or fluid leaks. The use of appropriate personal protective equipment (PPE) is non-negotiable; this includes eye protection, cut-resistant gloves, and sturdy footwear, with additional PPE as dictated by specific tasks. A disciplined risk assessment should be conducted for each service action to determine potential consequences and necessary precautions. Adhering to these warnings significantly reduces the probability of slips, burns, or other preventable injuries.
Required tools and test equipment are outlined to ensure repairs are performed with accuracy and efficiency. Common indispensable items include standard hand tools, torque wrenches, a multimeter for electrical checks, and manufacturer-recommended ignition and fuel system test accessories. The manual also specifies the use of proper alignment guides, service stands, and OEM replacement parts to maintain tolerances and performance. It is important to verify tool calibration and inspect test leads for integrity before use, as faulty instruments can lead to incorrect diagnoses. Proper organization of fasteners and components during disassembly helps prevent reassembly errors and ensures that replacements meet original specifications. Following these tool requirements supports consistent diagnostics, safe servicing, and dependable reassembly of the machine.
Product specifications and identification
The CRAFTSMAN 917.379120 lawn tractor carries a unique model designation that identifies the specific configuration and production batch for service and parts compatibility. Begin by locating the model plate or data tag on the chassis, typically near the engine shroud or under the seat area, and verify the model number 917.379120 as well as the serial number. Recording these numbers before performing maintenance simplifies parts ordering and ensures you reference the exact unit. When documenting the serial number, note the factory code, production year, and any prefix or suffix characters that may appear in the stamping, as early or late production runs can have subtle hardware differences. For accuracy, photograph the data tag from multiple angles and store the images with your service records for quick validation during future service events.
Engine specifications and fuel requirements for this model are tailored to deliver reliable starting, efficient fuel consumption, and consistent power output across typical mowing tasks. The unit is equipped with a four-stroke gasoline engine that requires a clean, unleaded fuel with an octane rating appropriate to the engine’s specification, usually 87 octane or higher as recommended by the manufacturer. Always use fresh fuel and add a fuel stabilizer if the machine will be stored for extended periods to prevent varnish buildup and degraded performance. Check the engine oil type and capacity listed on the owner’s manual label near the dipstick, and maintain the correct oil level with the engine off and cool to avoid overfilling or underfilling, which can affect lubrication and sensor readings. When performing routine maintenance, inspect air filters, fuel lines, and the spark plug for signs of wear or contamination, replacing parts that show excessive wear to maintain optimal combustion efficiency and throttle response.
Deck and cutting height specifications define the cutting system’s performance and cut quality. The deck is a mid-sized, belt-driven unit designed to provide a balanced cut across a variety of lawn conditions, with adjustable cutting heights typically ranging through a multi-position lever or dial. Verify the deck size and type stamped or labeled on the underside or the sidewall of the deck to confirm compatibility with blades, mulching inserts, and anti-scalp wheels. For accurate maintenance, measure the deck spindle spindle bearings and verify blade-to-spindle clearance, ensuring there is no excessive play that could degrade cut quality. The cutting height range is usually indicated by numbered positions; align the adjuster with the desired height, then recheck after the first few minutes of operation to confirm uniform height across all wheels. When replacing blades, use the recommended blade type and torque the mounting bolts to the specified value to ensure the blades are secured properly and to reduce the risk of imbalance or vibration during operation.
The disassembly and inspection fundamentals for the CRAFTSMAN 917.379120 require careful attention to safety, tool selection, and orderly process. Begin by disconnecting the power source and removing the battery if applicable to prevent accidental starting. Establish a clean work area with labeled containers for fasteners and small components, and photograph key assemblies before removal to aid reassembly. When handling the cutting deck and associated hardware, support the deck with a stand or blocks to prevent bending or torsion of blades and spindles, which can cause misalignment or injury. Use the appropriate hand tools or torque-measuring equipment to avoid over-tightening fasteners, as excessive torque can strip threads or damage structural components. Always verify that shutting points and linkage connections are secured after any disassembly before testing in a safe, controlled environment.
In belt and pulley inspection, inspect drive belts for signs of cracking, fraying, glazing, or chunking along the edges and surfaces. Replace worn or damaged belts with the correct OEM specification to maintain proper tension and belt life. Check pulleys for grooves, missing teeth, and surface wear, ensuring alignment with the belt path. Spindle housings and bearings should be checked for smooth rotation without wobble or unusual noise; if roughness or play is detected, remove and inspect bearings, replacing as necessary. Document belt tension measurements and pulley alignment using the manufacturer’s prescribed methods, and re-check after reassembly to confirm proper operation. Finally, inspect tensioners, idlers, and springs for uneven wear or sticking, addressing any binding issues before reinstalling the drive system.
For cutting deck removal and inspection, start by safely supporting the deck and removing any guards or shields that constrain movement. Detach the belt from the PTO pulley and remove locking components or pins that secure the deck to the mower frame. With the deck lowered on supports, inspect the blade adapters, spindle assemblies, and blade bolts for wear, cracks, or looseness, and replace as needed. Measure blade height, spindle height, and deck level to ensure proper cut and even wear upon reassembly, performing any needed level adjustments. Clean and inspect deck surfaces for corrosion or deformation, and service the spindle bearings per OEM guidelines, including lubrication intervals and grease type. When reinstalling, follow the prescribed torque values and verify belt routing to prevent interference with the deck or blades during operation.
Drive system inspection and lubrication require careful evaluation of the transmission, axle shafts, and drive belt routing to ensure reliable propulsion and control. Inspect the drive belt for wear, glazing, and cracks, replacing it when degradation is evident. Examine the transmission case for leaks, and verify seals and gaskets; if seepage is detected, disassemble to inspect for improper seating or worn components, and replace parts as required. Lubricate all accessible grease points with the recommended lubricant, paying attention to differential or hydrostatic units if applicable, and wipe away excess to avoid attracting dirt. Check the condition of drive linkages, cables, and clamps for proper tension and alignment, adjusting as necessary. Finally, perform a functional test across a range of speeds to confirm smooth engagement, accurate gearing, and consistent power delivery, documenting any abnormal noise or vibration and addressing root causes before returning the equipment to service.
Initial troubleshooting framework
When approaching any repair or maintenance task for the CRAFTSMAN 917.379120, a structured and symptom-driven mindset yields faster and more reliable results. Begin by establishing a calm baseline of the machine’s current condition, noting any recent usage patterns, noises, vibrations, or changes in performance. A robust troubleshooting framework centers on distinguishing between mechanical, electrical, and fuel-related causes, then progressing through a logical sequence of checks that confirm or rule out each potential issue. Documenting observed symptoms and the sequence of events leading up to the problem helps ensure repeatability and clarity when communicating with customers or team members.
A symptom-based diagnostic flow starts with critical safety checks to prevent injury and equipment damage. Before removing any covers or inspecting components, disconnect the spark plug wire and ground it to prevent accidental starting. Verify that the unit is on a stable work surface and that all controls are in the off position. Once safety is ensured, observe exterior conditions such as fuel leaks, loose fasteners, or obvious wear patterns that may indicate misalignment or impending failures. Collecting these initial observations provides a foundation for the deeper diagnostic steps and helps prioritize the most probable failure sources.
Common operational issues typically span starting difficulties, underperforming power, and unexpected shutdowns. For starting problems, assess the fuel system, air intake, and ignition timing. Check fuel quality, carburetor cleanliness, and choke operation, and evaluate the air filter for clogging or damage. If the engine runs but lacks power or stalls under load, inspect the exhaust clearance, muffler condition, and any obstruction in the cooling system, as overheating can mimic other faults. When shutdowns occur without clear cause, examine the safety interlocks, electrical connections, and the kill switch circuit, as well as possible short circuits or broken wires that interrupt normal operation.
Electrical system quick checks focus on ensuring continuity, proper voltage, and reliable grounding. Start with a visual inspection of wiring harnesses for fraying, loose connectors, and corrosion at terminal points. Use a digital multimeter to verify battery voltage, charging system output, and continuity along critical pathways such as the ignition coil and safety interlocks. Confirm that fuses and relays are seated correctly and free of corrosion, and test for any parasitic drain that could lead to slow startups or intermittent operation. Finally, inspect the safety switch circuitry and any microcontroller or sensor interfaces for fault codes or loose programming that could cause unpredictable engine behavior, and document any findings for follow-up repairs.
Engine systems service procedures
Fuel system inspection and maintenance The fuel system beginning with proper fuel quality is essential for reliable engine operation. Start by inspecting the fuel container, hoses, clamps, and lines for signs of wear, cracking, or leaks, and replace any degraded components promptly to prevent fuel leakage and potential fire hazards. Check the fuel line for kinks or obstructions that could restrict flow, and ensure the connection to the carburetor or fuel injection system is secure and free from corrosion. When inspecting the fuel tank, look for rust, sediment, or contamination that could clog filters or jets; drain or replace contaminated fuel and use fresh gasoline with the correct octane rating as specified by the manufacturer. Replace the fuel filter at recommended intervals or whenever flow limitations are observed, and always clean or replace the inline screen to maintain proper fuel delivery. During maintenance, inspect the fuel shutoff valve for proper operation, ensuring it closes fully to prevent residual fuel from dripping when the system is powered down. Finally, verify that the fuel system venting is unobstructed; a blocked vent can cause vapor lock and erratic engine behavior, particularly in warm ambient conditions. Air intake and filtration service A clean air intake and filtration system is critical for optimal combustion and engine longevity. Begin by inspecting the air filter housing for cracks or loose fasteners, ensuring an airtight seal when the cover is installed. Remove the filter element and inspect for excessive dirt, oil saturation, or damage; replace the filter if its pleats are collapsed or if there is any perforation. Clean the air intake passages to remove any debris that could restrict airflow, taking care not to damage delicate fins or gaskets. When reinstalling the filter, confirm the correct orientation and seating to maintain a proper seal; a misaligned filter can allow unfiltered air to bypass the filtration media. If a secondary or pre-cleaner is present, brush or vacuum away surface dust before reassembly. Periodically check the carburetor or throttle body for excessive dirt buildup around the metering screws and transitions; use appropriate cleaners sparingly to avoid swelling seals. Ensure the air intake system is free of obstructions such as leaves, grass clippings, or debris that could reduce engine performance or cause overheating. Ignition and safety interlock testing Reliable ignition is essential for starting and maintaining steady engine operation, and safety interlocks help prevent accidental operation. Begin by inspecting spark plugs for electrode wear, fouling, or excessive gap; replace plugs that show dark, oily deposits or a degraded insulator, and adjust the gap to the manufacturer’s specification. When testing ignition coils and wiring, verify continuity with a multimeter and look for any signs of frayed insulation or loose connections that could cause misfires or intermittent starting issues. If a capacitive discharge or electronic ignition system is used, follow the service manual’s procedure to test for proper spark timing and waveform without removing critical components unnecessarily. For safety interlocks, confirm that all associated switches—such as blade engagement, seat, or key switches—function correctly by attempting normal starting and confirming that the engine cannot start if a safety condition is not met. Additionally, check the ignition kill switch and grounding connections to ensure they return the engine to a safe off state when activated. After testing, review any fault codes or diagnostic indicators and perform a functional test under light load to observe stable idle, smooth acceleration, and consistent shutdown when required.Lubrication and hydraulic systems are critical to the reliable operation and longevity of the CRAFTSMAN 917.379120 mower. Regular lubrication reduces friction, prevents wear, and helps maintain consistent performance under varying load and temperature conditions. Begin with a clean engine and hydraulic reservoir area to prevent contaminants from entering the system during service. Use manufacturer-approved lubricants and follow the specified viscosity ranges to ensure compatibility with seals, hoses, and metal surfaces. When in doubt, consult the owner’s manual for the exact lubricant grade and any special instructions unique to this model. After servicing, run the system briefly to circulate the lubricant and check for leaks or abnormal noises that could indicate incorrect installation or component wear.
Oil change procedures and intervals are foundational for engine health and overall hydraulic system performance. Establish a routine that aligns with operating hours and environmental conditions, performing changes more frequently in dusty or high-load environments. Before draining oil, warm the engine to operating temperature to ensure complete drainage of contaminants, then shut off and prevent accidental restarting. Remove the drain plug and collect old oil in an appropriate container, noting the volume for reference. Replace the oil filter if equipped, install a new gasket seal, and refill with the recommended oil to the correct level, verifying the sight glass or dipstick reading. Finally, start the engine and run for a few minutes, checking for leaks and ensuring the oil pressure stabilizes within specification. Record the maintenance date and hours for future scheduling, so intervals remain consistent with the mower’s operating demands.
Hydraulic drive and deck lift lubrication require attention to fluid quality and component motion. Inspect hydraulic hoses for cracking, bulging, or signs of leakage, and replace any damaged sections promptly to prevent pressure loss. Ensure hydraulic fluid is clean and within the specified range, replacing the reservoir filter if the design includes one. When lubricating deck lift components, apply a light, compatible lubricant to pivot points, pins, and linkage joints to reduce stiffness and extend life. Avoid over-lubricating, which can attract dust and grime or contaminate the hydraulic fluid. During operation, monitor for changes in deck height accuracy or sluggish lift, which may indicate air entrainment, fluid contamination, or worn seals that need further diagnosis beyond lubrication. Proper lubrication reduces resistance and ensures smooth, precise deck adjustments during cutting work.
Filter replacement guidelines are essential for maintaining hydraulic efficiency and engine protection. The hydraulic system relies on clean filtration to prevent particulate matter from accelerating wear on pumps, valves, and actuators. Follow the manufacturer’s recommended interval for replacing hydraulic and engine oil filters, recognizing that tougher operating conditions may necessitate more frequent changes. When replacing filters, ensure you pre-fill or prime the new filters if the design requires it, and lubricate gasket seals with a small amount of clean oil to ensure a proper seal on installation. Dispose of used filters and fluids in accordance with local environmental regulations, and reset any service indicators if the mower is equipped with a maintenance reminder system. After installation, bleed the hydraulic lines as required by the design to remove trapped air, then run the system to confirm proper pressure, smooth operation, and the absence of leaks. Document filter change dates and hours to maintain consistent maintenance scheduling and system reliability.
The electrical system and wiring harnesses in the CRAFTSMAN 917.379120 are designed to deliver reliable power delivery while providing safe, repeatable start-up and operation. Before performing any work, ensure all power sources are disconnected and the machine is isolated from any external charging equipment to prevent accidental energization. Begin with a careful inspection of the battery terminals, cables, and connectors for signs of corrosion, fraying, or loose connections. Clean and secure all connections as needed, and replace any damaged wiring harnesses to prevent intermittent faults that could compromise safety or performance. A well-maintained harness helps prevent miscommunication between the ignition, safety interlocks, and the charging system, which is essential for predictable operation during maintenance tasks.
Battery charging and connections focus on ensuring a stable, sufficient charge without overcharging. Start by verifying the battery type installed in the unit and confirm compatibility with the charging system specifications. Check the charging leads for cracks or degradation and confirm that the battery vent caps (if present) are secure. Use a multimeter to measure the battery voltage at rest and under load, ensuring it remains within the recommended range. If the system shows persistent low voltage, inspect the charging circuit for failed diodes, blown fuses, or loose connectors, and replace faulty components promptly to prevent battery damage or insufficient cranking power.
Charging system testing involves confirming that the alternator or charging coil, regulator, and associated circuitry function as a cohesive unit. With the engine off, inspect the electrical harness routes to ensure they are free from chafing against sharp edges or hot components. When the system is operational, monitor the charging voltage at the battery terminals; a healthy system typically maintains a specific voltage window dictated by the battery type, often around 12 to 14 volts for most 12-volt configurations. Use a non-contact infrared thermometer to spot unusually hot wiring or connectors, which can indicate excessive current draw or failing insulation. If charging anomalies are detected, isolate the fault by methodically testing the regulator, rectifier, and wiring runs, documenting measurements to support accurate fault isolation and efficient repairs.
Safety interlocks and switch testing ensure that operator protections are functioning as designed, preventing starting or operation when unsafe conditions exist. Begin by confirming that the seat switch, brake engagement, and blade engage/kill circuits are wired into the control module in the correct sequence. Use a test lead to simulate interlock conditions and observe whether the ignition and safety circuits correctly cut power to critical systems when a safety condition is triggered. Verify that all wiring connectors to the interlock module are clean, dry, and securely mated, as loose or corroded connections can lead to intermittent starts or unintended operation. Document any failures and replace faulty interlock components following the manufacturer’s torque specifications and wiring color codes to maintain proper circuit integrity and operator safety throughout the service process.
The deck, spindle, and blade assembly are critical to the cutting performance and longevity of your CRAFTSMAN lawn mower. Proper care begins with understanding the role of each component and the common wear points that can affect cutting quality. Regular inspection and maintenance help prevent uneven cuts, excessive noise, and blade damage. Before performing any service, ensure the mower is on a level surface, the ignition is disconnected, and the cutting area is cool to avoid accidental injury. Use the correct tools and refer to the manufacturer’s torque specifications when reassembling any fasteners to maintain safety and performance.
Blade removal and sharpening guidelines: Start by safely removing the spark plug wire and disconnecting the battery if equipped to prevent accidental starting. Remove the blade nut, washer, and blade from the spindle, noting the orientation of the blade so it can be reinstalled correctly. Inspect the blade for nicks, cracks, or excessive dullness; a damaged blade should be replaced rather than repaired. When sharpening, preserve the original blade geometry and balance the blade after sharpening to prevent vibration and bearing wear. Reinstall the blade with the correct edge orientation, reinstall the washer and nut, and torque to the manufacturer’s specification, ensuring the blade is centered and properly seated to avoid contact with the deck or spindle housing. After reassembly, perform a safe spin test by briefly rotating the blade with the spark plug wire disconnected to confirm there are no unusual noises or clearances.
Spindle bearing inspection and replacement: Access the spindle by removing the blade and any shielding as required by the model. Manually rotate the spindle to feel for roughness, binding, or play; audible grinding or a gritty feel indicates bearing wear. Check for excessive vibration during operation, which can signify worn bearings or misalignment. If replacement is necessary, follow the precise procedure to remove the spindle assembly, preserve any shims or spacers, and install a new bearing kit according to the service manual’s torque and preload specifications. After installation, verify smooth spindle rotation without wobble and ensure the spindle is properly aligned with the blade mounting surface to maintain balanced cutting and prevent blade edge damage. Reassemble all guards and shields securely to protect the operator and ensure safe operation.
Deck alignment and adjustability: A level cutting deck is essential for uniform height across the blade path. Place the mower on a level surface and measure the deck height at multiple points to determine any tilt or warp. Use the deck adjustment levers or screws to correct any misalignment, following the manufacturer’s recommended steps for each model variation. After adjustment, recheck the deck’s levelness from front to rear and side to side, ensuring consistent gap clearance between the blade tip and the underside of the deck. If the deck shows signs of structural wear or uneven wear patterns, inspect the spindle, blade, and mounting hardware for looseness, and tighten or replace as needed. Regularly cleaning the under-deck area and removing trapped grass buildup will help maintain consistent cutting performance and extend the life of the drive belts and grove bearings. Finally, reattach any guards and measure the blade-to-deck clearance to confirm it remains within the specifications outlined by the service manual.
Diagnostics and repair procedures
Effective diagnostics begin with a systematic approach to ruling out common failures that can masquerade as more complex issues. Start by inspecting the exterior for obvious damage, loose fasteners, and compromised electrical connections. Verify fuel quality and freshness, as degraded fuel can cause hard starts, rough idle, or loss of power that might be mistaken for mechanical faults. Check the air filter, spark plug condition, and carburetor/fuel system for signs of clogging or contamination, as these are frequent culprits in outdoor power equipment. Employ hands‑on testing to observe operating symptoms under load, noting any unusual sounds, vibrations, or smoke that could indicate misalignment, bearing wear, or temperature-related problems. Maintain clear documentation of observed conditions, as precise symptom logging expedites accurate fault isolation and reduces unnecessary part replacement.
Component replacement procedures require careful preparation and adherence to torque and alignment specifications to ensure reliable operation after service. Before removing any part, disconnect the spark plug boot and relieve any stored energy in the system to prevent accidental starts. When replacing the spark plug, use the correct heat range and gap specification recommended by the manufacturer, and inspect the electrode for wear or fouling. For carburetor or fuel system repairs, drain fuel from the lines and bowls, replace gaskets and seals as needed, and reset the idle and mixture settings according to the service manual. When addressing air intake issues, inspect the air filter housing for cracks and ensure the filter media is properly seated to prevent unmetered air from entering the engine. For cooling components, ensure the cooling fins are clean and free of debris, and replace any damaged shrouding or guards to maintain proper airflow. Always torque fasteners to the specified values using a calibrated torque wrench and follow the prescribed sequence to avoid warping or uneven clamping.
Reassembly checks and torque specifications are critical to restoring safe and dependable performance after any repair. Begin with securing major assemblies in their correct orientation, verifying that gaskets, seals, and o‑rings are correctly positioned to prevent leaks. Reconnect electrical connectors with attention to polarity and locking mechanisms, and test for proper continuity with a multimeter where applicable. After initial assembly, perform a thorough inspection for loose components, misalignments, or interference with moving parts. Run a functional test at low, then full operating speeds, paying close attention to vibrations, exhaust emissions, and temperature indicators. Record all measured values, including torque readings and assembly clearances, to provide a verifiable maintenance history and to assist with future diagnostics if the unit exhibits any irregularities later in service. Adhere strictly to the engine and drive system specifications to maintain reliability and safety during operation.
The maintenance schedules for the CRAFTSMAN 917.379120 are designed to keep the machine operating reliably under typical consumer use. Establish a baseline service interval aligned with manufacturer recommendations, and adjust based on operating conditions such as frequency of use, load demands, and climate. Create a practical calendar that marks key tasks like air filter inspection, spark plug checks, and belt tension assessment at regular intervals. Regular preventive maintenance helps prevent unexpected downtime, reduces the risk of component wear, and extends the overall life of the equipment. Maintain a simple checklist that can be referenced during each maintenance event to ensure consistency and thoroughness.
Record keeping and service logs are essential for tracking the machine’s history and planning future interventions. Each entry should include the date of service, mileage or hours of operation if applicable, parts replaced, and any observations that require follow-up. Use a consistent format for documenting torque values, lubricant types, and consumable replacements to facilitate quick reviews by technicians or owners. Keeping an organized log also supports warranty considerations and resale value, as it provides verifiable evidence of regular maintenance. Store logs in a dry, accessible location, and consider maintaining digital backups in addition to physical copies for redundancy.
Storage and long term care recommendations are critical to prevent deterioration when the unit will be idle for extended periods. Before storage, perform a thorough cleaning to remove dirt, debris, and corrosive residues that can accelerate wear. Drain or stabilize fuels according to the manufacturer’s guidance to prevent gum formation and varnish buildup in the fuel system and carburetor. For long-term storage, withdraw spark plug wires with care and protect ignition components from moisture, while ensuring the machine is supported properly to avoid deformation. In climates with extreme temperatures, consider seasonal protective measures such as fuel stabilizers, battery maintenance if applicable, and elevated storage to prevent moisture ingress. Regularly re-inspect stored equipment to verify that seals remain intact and that no signs of corrosion or pest ingress have appeared during the idle period.
Troubleshooting reference charts
Electrical symptoms quick chart: Begin troubleshooting by validating power to the unit and confirming all safety switches are engaged properly. Inspect the battery or power source for proper voltage and terminals for corrosion or looseness, cleaning or tightening as needed. Use a digital multimeter to verify continuity across fuses, relays, and switches, and check for parasitic drains that could indicate a short or faulty component. When symptoms point to control circuitry, reseat connectors to ensure solid contact and inspect wiring harnesses for signs of wear, chafing, or pinched insulation. Document any fault codes or irregular readings, as these details guide rapid identification of the faulty module or sensor and help prioritize parts replacement or repair steps.
Fuel and engine performance quick chart: Start by confirming the fuel supply is clean, free of water, and at the correct pressure for the carburetor or fuel injection system. Inspect the air intake for obstructions, including dirty air filters or collapsed ducts, and replace or clean as necessary to restore proper air-fuel mixture. Check the spark plug(s) for fouling, improper gap, or wear, and replace with the recommended type if needed, ensuring proper torque and gap. Examine the ignition coil, kill switch, and grounding paths to rule out intermittent signals that could cause hard starting or inconsistent running. If performance issues persist, verify governor linkage, carburetor settings, and fuel lines for leaks or cracks, and perform a controlled test run to observe throttle response, RPM stability, and any abnormal exhaust or smoking signs.
Safety system indicators quick chart: Begin by verifying that all safety interlocks, such as blade engagement, brake, and seat or handlebar switches, are functioning and returning safe states when released or disengaged. Inspect indicator lights and gauges for proper operation, ensuring they illuminate appropriately during startup and deactivate when safe conditions are met. Check the shutdown circuits and fuses related to safety systems for continuity and correct routing, replacing any blown fuses or damaged wiring promptly. For intermittent indicators or false alarms, reseat or replace the associated sensors, and examine shielding or grounding to prevent EMI or voltage spikes from causing erroneous readings. Finally, validate that the operator presence acknowledgment and dead-man switch mechanisms are aligned with the manufacturer's torque and travel specifications to avoid accidental machine startup or unexpected halts during operation.
The reassembly phase requires careful attention to the sequence of component installation to ensure proper alignment and function. Begin by confirming that all fasteners are clean, thread wells are free of debris, and lubricants are applied as specified in the service data. Install major assemblies in the reverse order of disassembly, taking care to align shafts, gears, and linkages accurately. After each major subsystem is reattached, perform a brief manual check to confirm free movement without binding or excessive play. Recheck all electrical connections for secure crimps and proper routing away from hot surfaces or moving parts, then restore any removed guards or shields to their original mounting positions. Finally, verify that every fastener has the correct torque value as detailed in the torque specification sheet, and re-torque after the initial test run if required by the manufacturer’s guidelines.
System functional tests after service are designed to validate the integrity of the machine under normal operating conditions. Start with a controlled no-load test to observe smooth engine operation, verifying proper idle speed, throttle response, and smooth transitions between gear ranges if applicable. Listen for abnormal noises, vibrations, or smoke, and check for any fuel leaks or excessive exhaust emissions. Run through all safety interlocks and shutdown procedures to confirm that the unit stops promptly when a control is engaged. Monitor temperature readings on accessible surfaces to ensure cooling systems are effectively removing heat, and verify that the cooling fan engages and cycles correctly. Document any deviations and address them before proceeding to a full-load test.
Operational checklists for safety and performance provide a structured approach to confirm that the equipment will perform reliably in the field. Inspect all guards, shields, and safety devices for damage and secure mounting. Verify that starting and stopping controls function without sticking or excessive resistance, and confirm that safety switches prevent operation with guards removed. Check belt tension, pulley alignment, and drive components for wear or misalignment that could affect performance. Ensure fuel lines, air hoses, and electrical harnesses are routed away from hot surfaces, moving parts, and sharp edges to prevent chafing. Perform a short functional run at varied speeds to validate performance across the full operating range, paying close attention to load response, acceleration, deceleration, and any unexpected shutdowns. Record the outcomes of each test step to support future maintenance planning.
Final cleaning and inspection conclude the service procedure by restoring the unit to a neat, professional condition while confirming internal cleanliness and proper function. Remove any residual lubricants from external surfaces with a non-abrasive cleaner, and wipe down control panels to ensure legibility of indicators and labels. Inspect the air intake and cooling passages for obstructions, and clean or replace filters as required. Check the exhaust path for leaks and secure mounting of any muffler components. Perform a final visual inspection of all wiring harnesses, connectors, and fasteners to ensure nothing has loosened during testing. Apply any protective coatings or rust inhibitors where recommended, then perform a test run to confirm stable operation and absence of abnormal indicators. Prepare a concise service report summarizing the procedures performed, test results, and recommended maintenance intervals.
Appendix and resources provides essential reference materials that support ongoing maintenance, safe operation, and reliable repair of the CRAFTSMAN 917.379120. This section compiles wiring diagrams and schematics overview, torque specifications reference, and recommended replacement parts and suppliers into a single, accessible resource. By understanding the wiring layouts, technicians can diagnose electrical faults accurately and minimize guesswork during troubleshooting. The torque specifications reference ensures fasteners are tightened to the correct values, preserving mechanical integrity and preventing failures due to over- or under-torque. Together, these resources help maintain equipment performance, extend service intervals, and support compliant, safe repair practices.
The wiring diagrams and schematics overview section provides high-level diagrams that map the electrical paths for ignition, charging, safety interlocks, and control circuits. It is important to study the connector pinouts and color codes in conjunction with the component layout to identify potential short circuits, open circuits, or mismatched connections. When tracing a circuit, begin at the power source and work methodically toward the load, checking for continuity and proper ground references at each step. This overview is designed to supplement the main service manual, offering quick reference points for common electrical issues encountered during field service or in-shop repairs. Always ensure power is isolated and lockout procedures are followed before performing any electrical testing or disassembly.
The torque specifications reference section consolidates critical fastener values for the engine, chassis, and deck assemblies. Adhering to these specifications is vital to maintain compression, prevent loosening under vibration, and ensure safe operation during dynamic loads. Use a calibrated torque wrench and apply the correct sequence for multi-fastener assemblies to achieve uniform clamping force. Documented values typically cover head bolts, blade spindle hardware, blade adapter screws, mower deck fasteners, cotter pins, and safety-related components. When reassembling, confirm clearances and proper alignment first, then torque to the recommended specification in stages as required by the design and service notes.
The recommended replacement parts and suppliers section lists components commonly subject to wear or failure, along with vetted supplier options. This includes ignition components, fuel system parts, bearings, seals, gaskets, belts, and electrical connectors that match the original specifications. Prioritize OEM or OEM-equivalent parts to maintain compatibility, performance, and warranty considerations. Maintain a brief parts inventory and supplier contact log for quick access during repairs, including part numbers, approximate lead times, and return policies. Keeping track of these resources supports efficient repairs, practical maintenance planning, and consistent machine performance across service intervals.