3to 11hp 4-cycle l-head engines - Small Engine Suppliers

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CARBURETION TROUBLESHOOTING START IDLE ACCELERATE HIGH SPEED AIR SYSTEM PROBLEMS Plugged Air Filter Leaky Carburetor Gasket Throttle or Choke Shafts Worn Choke Not Functioning Properly Hard Starting Rich Idle ` ` ` ` ` ` ` ` ` ` Fuel Leak at Carburetor Engine Floods Will Not Idle Idles with Needle Closed Hunts - Erratic Idle Idles Fast - Lean ` ` ` Will Not Accelerate Over Rich Acceleration Hesitates ` Will Not Run at High Speed Low Power ` ` Hunts at High Speed Runs with Needle Closed Engine Overspeeds ` ` ` ` Plugged Atmospheric Vent Air Bleed Restricted Damaged or Leaky "O" Rings DIAPHRAGM SYSTEM PROBLEM Damaged Diaphragm Stuck or Dirty Ball Check Diaphragm Upside Down FUEL SYSTEM PROBLEM Plugged Tank Filter or Vent Fuel Pick-up Restricted Idle Port Restricted Damaged Adjustment Needles Incorrect Float Height Main Nozzle Restricted Dirty, Stuck Needle and Seat Fuel Inlet Plugged ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` ` 14
TESTING 1. After repeated efforts to start the engine using the procedure listed in the operator’s manual fail, check for spark by removing the high tension lead and the spark plug. Install a commercially available spark plug tester and check for spark. If spark is evident and acceptable, proceed to step 2. If no or weak spark, see Chapter 8 under "Testing". 2. Visually inspect the spark plug for a wet condition indicating the presence of gasoline in the cylinder. 3. If the spark plug is dry, check for restrictions in the fuel system before the carburetor. If the spark plug is wet, continue with step # 7. Check to see if the fuel cap vent is open. With a proper draining receptacle, remove the fuel line clamp on the carburetor fuel inlet and pull the fuel line off the fitting to examine the fuel flow and fuel condition. 4. Remove the air cleaner element or air cleaner assembly to visually check that the choke shutter completely closes or check to see if fuel comes out from the main nozzle during priming. 5. If the fuel flow is adequate and no fuel is evident during priming, the carburetor will need to be removed for service. See “Service” in this chapter or consult the “Carburetion Troubleshooting” chart if other problems exist. Improper fuel flow indicates the fuel, fuel line, filter or tank require cleaning or replacement. 6. Check the engine compression using a commercially available compression tester and follow the tester’s recommended procedure. Low compression, a dry spark plug, adequate fuel flow, and a known good functional carburetor indicates an internal engine problem exists. See Chapter 9 under “Engine Operation Problems.” 7. A wet spark plug indicates fuel is being supplied by the carburetor. The engine may be flooded by a restricted air filter, carbon shorted or defective spark plug, excessive choking or over priming, improperly adjusted or defective carburetor, or the wrong ignition timing. With the spark plug removed and a shop towel over the spark plug hole, turn the engine over slowly 3 or 4 times to remove excess gasoline from the engine cylinder. CAUTION: KEEP ALL COMBUSTIVE SOURCES AWAY. AVOID THE SPRAY FROM THE SPARK PLUG HOLE WHEN CRANKING THE ENGINE OVER. 8. Replace the air filter if restricted or oil soaked. Replace the spark plug if questionable. Install the spark plug and high tension lead and retry starting the engine. 9. If the engine floods and fails to start, the carburetor may require service. See the preceding “Carburetion Troubleshooting” chart for additional causes. If the carburetor is functioning properly the problem may be ignition timing related. See Chapter 8 under “Ignition Troubleshooting.” SERVICE CARBURETOR PRE-SETS AND ADJUSTMENT NOTE: EMISSION GRADE CARBURETORS HAVE FIXED IDLE AND MAIN JETS. THE ABSENCE OF THE ADJUSTING SCREW INDICATES A FIXED JET OR RESTRICTOR AND NO ADJUSTMENT IS NECESSARY. THE IDLE RESTRICTOR ON AN EMISSIONS CARBURETOR APPEARS AS AN ADJUSTABLE SCREW. THIS IS NOT ADJUSTABLE AND MUST REMAIN TIGHT FOR PROPER OPERATION. The idle on an emission is metered using a threaded restrictor (see Illustration). Proper torque of this screw is critical and should be torqued to 5-8 in. lbs. or .5 to 1 nm, if not, it may vibrate loose. When the restrictor is placed in the idle circuit passage it is capped with a tamper resistant plastic cap. Tampering is considered the rejetting or modification through resizing of the jet. If the jet is removed for cleaning it must be recapped to prevent tampering when it is re-installed. CAP IDLE RESTRICTOR Before adjusting any mixture screws the necessary carburetor presets should be made. Check for the proper governor adjustments as outlined in Chapter 4. Identify the correct carburetor model and manufacturer to find locations of the high and low speed adjustment screws. Check the throttle control bracket for proper adjustment allowing a full choke shutter position. See Chapter 4 under "Speed Controls and Linkage". Check to see if the normal maintenance procedures have been performed (oil changed, fresh fuel, air filter replaced or clean). Consult microfiche card #30 to find the correct R.P.M. settings for the engine, or consult Service Bulletin #107 for the revised safety specification for rotary type power lawn mowers. Start the engine and allow it to warm to operating temperature. The carburetor can now be adjusted. 15
Page 1 and 2: TECUMSEH T E C H N I C I A N ' S H
Page 3 and 4: GOVERNOR GEAR AND SHAFT SERVICE....
Page 5 and 6: CHAPTER 1 GENERAL INFORMATION ENGIN
Page 7 and 8: ENGINE OIL Use a clean, high qualit
Page 9 and 10: GENERAL INFORMATION CHAPTER 2 AIR C
Page 11 and 12: CHAPTER 3 CARBURETORS AND FUEL SYST
Page 13 and 14: IMPULSE FUEL PUMPS Impulse fuel pum
Page 15 and 16: CARBURETOR IDENTIFICATION Tecumseh
Page 17: ENGINE TROUBLESHOOTING Engine Will
Page 21 and 22: DISASSEMBLY PROCEDURE NOTE: Engines
Page 23 and 24: Diaphragm Carburetors 1. Remove the
Page 25 and 26: ASSEMBLY Welch Plugs To install a n
Page 27 and 28: 4. Install the hinge pin from the o
Page 29 and 30: Throttle Lever Remove the throttle
Page 31 and 32: ENGINE OVERSPEEDING 1. If the engin
Page 33 and 34: SPEED CONTROLS AND LINKAGE Many dif
Page 35 and 36: HORIZONTAL SHAFT ENGINES IDLE SPEED
Page 37 and 38: VERTICAL SHAFT ENGINES HIGH SPEED A
Page 39 and 40: GENERAL INFORMATION CHAPTER 5 REWIN
Page 41 and 42: CAUTION: THIS REWIND SPRING IS NOT
Page 43 and 44: 2. Place the pulley assembly into t
Page 45 and 46: at the outer edge against the gear
Page 47 and 48: CONVERTING ALTERNATING CURRENT TO D
Page 49 and 50: BASIC CHECKS Before going into exte
Page 51 and 52: TROUBLESHOOTING ELECTRICAL CHARGING
Page 53 and 54: 18 Watt A.C. Lighting Alternator Mo
Page 55 and 56: NOTE: ON OLDER POINT IGNITION SYSTE
Page 57 and 58: 5 Amp Alternator System Regulator-R
Page 59 and 60: 7 Amp Alternator System Regulator-
Page 61 and 62: SERVICE This section covers the ser
Page 63 and 64: CHAPTER 7 FLYWHEEL BRAKE SYSTEMS GE
Page 65 and 66: SERVICE If the brake system fails t
Page 67 and 68: CHAPTER 8 IGNITION GENERAL INFORMAT
Page 69 and 70:
The condenser acts as an electrical
Page 71 and 72:
TESTING PROCEDURE 1. Check for spar
Page 73 and 74:
Begin the procedure by replacing th
Page 75 and 76:
Other Solid State Systems The follo
Page 77 and 78:
LUBRICATION SYSTEMS The lubrication
Page 79 and 80:
ENGINE OPERATION PROBLEMS ENGINE KN
Page 81 and 82:
TESTING ENGINE KNOCKS 1. Check the
Page 83 and 84:
5. Check the engine valve lash. Res
Page 85 and 86:
CYLINDERS Visually check the cylind
Page 87 and 88:
Use a ring expander to remove and r
Page 89 and 90:
VALVES The valves should be checked
Page 91 and 92:
Late production top mounted breathe
Page 93 and 94:
COUNTERBALANCE SERVICE To correctly
Page 95 and 96:
FOUR CYCLE TORQUE SPECIFICATIONS Th
Page 97 and 98:
ENGINE SPECIFICATIONS STANDARD POIN
Page 99 and 100:
ENGINE SPECIFICATIONS STANDARD POIN
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SOLID STATE AND EXTERNAL IGNITION A
Page 103 and 104:
SOLID STATE AND EXTERNAL IGNITION A
Page 105 and 106:
SOLID STATE AND EXTERNAL IGNITION (
Page 107 and 108:
OIL SEAL DRIVER FLYWHEEL KNOCK-OFF
Page 109 and 110:
DECIMAL/FRACTION CONVERSIONS .016 =
Page 111 and 112:
SEARS CRAFTSMAN CROSS REFERENCE CHA
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3to 11hp 4-cycle l-head engines - Small Engine Suppliers

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