FOUR-CYCLE ENGINE TROUBLESHOOTING FLOW CHARTS

Transcription

1 FOUR-CYCLE ENGINE TROUBLESHOOTING FLOW CHARTS TROUBLESHOOTING

2 The ability to troubleshoot a problem quickly and accurately is one of the most valuable resources or "tools" that a technician can possess. A systematic approach to help you get to the root of a problem faster will mean faster turnaround time, better service, and lower service costs for your customers. Your trade volume will increase, (and so will your income), and each satisfied service customer becomes a potential buyer of new products from you as well. PROBLEM Page Engine Will Not Start... Engine Hard to Start... Engine Runs But Stops After Period... 5 Engine Runs Erratically... 6 Engine Runs But Lacks Power... 7 Engine Overheats... 8 Engine Uses Excessive Oil... 9 Engine Uses Excessive Fuel... 0 The purpose of this booklet is to provide a systematic sequence for you to follow in troubleshooting common engine problems. The heading on each page identifies a particular problem, and the flow chart gives our recommendations for locating the cause of that particular problem.

3 Engine Will Not Start equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Check for adequate fresh fuel. Check vent hole in tank cap. Check for debris in bottom of tank. Check for spark using in-line style tester. Check spark plug type and gap setting. (Refer to appropriate service manual). If no spark, go to block 0. Connect clear plastic hose between fuel source and carburetor. Turn fuel on and check flow (crank engine if fitted with fuel pump). # 5 If blocked, locate and clear if slow, also check fuel pump and any filters or screens Check for presence of fuel at plug and in carburetor Perform compression check. throat. 9 8 Check for fuel in bowl, reset float, clean jets, Remove head visually inspect for leakage around readjust mixture needles, check choke and throttle. piston, valves, and gasket. 0 Check points/push rod or solid state components Clean/replace points (reset gap) or module. for proper settings. Test mechanical points or module with proper tester. Engine should now fire and run. If it will not start easily, refer to Hard Starting Chart. # WARNING: Gasoline is highly flammable. DO NOT remove fuel lines or check fuel flow near an open flame, sparks, cigarette, or any source of combustion. NOTE: Single cylinder engines (except K9) built since 965 are equipped with an automatic compression release. + Refer to compression test procedure in appropriate Service Manual.

4 Engine Hard To Start equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Check for adequate fresh fuel. Test for spark with in-line spark tester. Check fuel supply from tank to carburetor. Check air filter for obstructions. Clean bowl and main jet, reset float level. Readjust needles. Check choke and throttle plates. Set for fast idle. Check manifold for air leaks. Check battery charge, connections, and leads. Check starter motor. Check ACR lift*. Check for load (transmission in neutral). Engine oil too heavy. Check for sufficient cranking speed (75 RPM minimum). Disconnect Hydrostatic units. Check spark plug type and gap. Clean and reset mechanical points or solid state module. Check for poor connections or cracked leads. 5 Check ignition timing with timing light. 6 Refer to appropriate service manual. 7 Perform compression check or leakdown test Remove head visually inspect for leakage around piston, valves, and gasket. The above should improve starting capabilities; however, engine will required further tuning of ignition timing and fuel air adjustments when running to give optimum performance. *Refer to appropriate Service Manual. + Refer to compression test or leakdown test procedure in appropriate Service Manual.

5 Engine Runs But Stops After Period equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Heat buildup can change the characteristics and mode of operation of many components through thermal expansion, evaporation, and resistance in ignition systems. This may result in engine stoppages when warmed-up. Check for causes of excess heat, blocked cooling fins, or a restriction in the cooling air intake and/or exhaust system before attempting to correct the results of overheating. Check fuel tank vent, adequate fresh fuel, sediment in fuel, screen in fuel valve blocked. If dirt, water, or stale fuel is found, clean tank, screen lines, fuel bowl, and carburetor. Check fuel pump (if equipped). Check fuel delivery to carburetor. Repair pump and/or clear lines. Perform compression check or leakdown test Remove head and valves. Ream guides, resurface seats, clean valve stems, or other necessary repairs. Check for spark with in-line tester. Check spark plug type and gap. Check ignition timing with timing light. 7 Regap plug or install new plug. 8 Test any and all ignition components as necessary. 9 0 Replace any necessary components. Occasionally, condenser may "break down" after 5-0 minutes, but appear good on test. If symptoms persist after checking all areas, replace condenser. + Refer to compression test or leakdown test procedure in appropriate Service Manual. 5

6 Engine Runs Erratically equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Check fuel supply from tank to carburetor. Check fuel tank, vent, fuel screen or filter, dirt in tank, rate of fuel flow thorough line. Check carburetor bowl for sediment, clogged jets, and obstructions. # Clean out jets with compressed air or carburetor cleaner. 5 Check type, condition, and gap of spark plug. Check condenser and coil, points gap, timing, and plunger, or solid state module. Replace plug, points, condenser, or solid state module if found defective. 6 Check governor adjustment and operation. 7 8 Readjust or repair as necessary. 9 Check air filter and exhaust system for blockages. Clean or replace as necessary. 0 Check cooling systems for signs of blockage, etc. Clean as necessary. Remove cylinder head and valves. Check valve seats, springs, guides, and adjustments. Reseat valves, ream guides, adjust tappets as necessary. # WARNING: Gasoline is highly flammable. DO NOT remove fuel lines or check fuel flow near an open flame, sparks, cigarette, or any source of combustion. 6

7 Engine Runs But Lacks Power equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Carburetor adjusted incorrectly. Readjust refer to appropriate Service Manual. Air filter clogged. Replace air filter element. Exhaust system obstructed. 5 6 Clean out or replace. Ignition timing set incorrectly. 7 8 Readjust using power timing light. Poor compression due to leaking head gasket or valves. Determined by leakdown or compression test Remove head and reface valves, ream guides, grind or replace seats, adjust tappets, replace gasket. Worn cylinder bore and piston rings. Resize cylinder, replace piston and rings. + Refer to compression test or leakdown test procedure in appropriate Service Manual. 7

8 Engine Overheats equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Cooling systems clogged or obstructed. Remove baffles and shrouds. Clean debris from cooling fins. Clean and remove obstructions from air intake screen. Cooling fins on flywheel or block missing or damaged. Replace necessary parts. 5 Carburetor adjusted too lean. 6 Readjust refer to appropriate Service Manual. Check carburetor and manifold for leaks. 7 Check ignition timing, using power timing light. 8 Readjust timing. 9 Incorrect fuel being used. 0 Clean tank and replenish with clean unleaded gasoline. 8

9 Engine Uses Excessive Oil equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Check all external surfaces of engine for oil leaks or deposits. Perform crankcase vacuum test and/or leakdown test to establish engine condition. Refer to appropriate Service Manual. Visually inspect dipstick seal (not covered by manometer test or vacuum gauge). Replace if necessary. 5 6 Disconnect breather tube (closed breather and twin Tear down and inspect breather for correct function. cylinder models), run engine and observe if If OK, remove head and inspect bore and rings. exhaust emits burnt oil fumes. Observe if oil is blown from breather. 8 Indicated by high crankcase pressure, caused by 7 breather hole not punched through from crankcase Check for oil blowout around governor shaft. to valve box. Compare to similar block (remove breather assembly). Punch or drill out as necessary. 9

10 Engine Uses Excessive Fuel equipment, disable the engine as follows: ) Disconnect the spark plug lead(s). ) Disconnect negative (-) battery Check tank, cap, valve, and lines for leaks. Repair or replace as necessary. Check carburetor and float bowl for flooding. # Replace and reset float and valve. Adjust carburetor refer to appropriate Service Manual. 5 Check air filter element for blockage. 6 Replace. 7 8 Check plug type and gap, points gap (if equipped), and ignition timing. Regap plug or replace. Reset points and timing. 9 0 Check fuel pump where fitted into block for leaks. If fuel drains into crankcase, the oil level will rise. Repair or replace fuel pump. Check choke operation for retention in open position. Repair or replace. Check for blockage or restriction of carburetor bowl vent passage. # WARNING: Gasoline is highly flammable. DO NOT remove fuel lines or check fuel flow near an open flame, sparks, cigarette, or any source of combustion. 0

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12 ENGINE DIVISION, KOHLER CO., KOHLER, WISCONSIN 50 FORM NO.: TP--B ISSUED: 5/8 REVISED: /05 MAILED: LITHO IN U.S.A.