1.1. TROUBLE SHOOTING
For a satisfactory starting and running conditions of a gasoling engine, the following three requirementsmust be met: I . Thecylinder filled
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2. An appropriatecompressioninthecylinder.
3.Goodsparkatcorrecttimetoignitethemixture.
If all three requirements are not met simultaneously, an engine can not be started. There are also other factors such as heavyloadatstartingandtoolongexhaustpipecausinghighbackpressure,whichcontributetohardstarting.
The most common causes of enginetroublesare given below.
11-1 STARTINGDIFFICULTIES
11 - 1 - 1 FUEL SYSTEM
1)No gasolineinfuel tank, o r fuelcockclosed.
2)Carburetorinsufficientlychoked,especiallywhenengine is cold.
3)Water, dirt or gum in gasolinehinderingflow o f fuel to carburetor.
4)Inferior or poor grade gasoline not vaporizing satisfactorily to produce correct fuel mixture.
5)Needle valve in carburetorheldopenbydirt or gum.Thiscondition is ascertainedbyccontinuousfueldripfrom the carburetor during idling.
Sometimes,thistrouble is remediedbylightlytappingthefloatchamberwithascrewdriverhandleor thelike.
6)Due tocarburetorflooding,toomuch fuel introduced in thecylinderthroughcranking,makingthemixturetoo rich to he ignited.
When thishappens,removesparkplugandturntheengineover several timeswithstartingpulleyto evac’uate over-
richmixturethroughtheplughole. Keep carburetorchokeopenduringthisoperation. Dry sparkplugthoroughly
and reinstall, and try to start again.
11-1-2 COMPRESSION SYSTEM
When thefuelsystemandtheignitionsystemareeliminatedasthecauseof startingdifficultiesand loss of power,the
following are t o be chccked for possible lack of compression.
1 ) Cylinderdryafterlonginterruptionofoperation.
2)Loose or brokenspark plug. In thiscase, a hissingnoise is audible,duringcranking,madebyescapingmixture gas
in compression stroke.
3 ) Damaged headgasket or slack cylinderheadtightening. A similar hissing noise is producedduringcompression stroke.
4)Tappetclearanceincorrect.(See “6 - 3 - 8, 6) ADJUSTINGTAPPETCLEARANCE”)
If the compression is not recovered after correcting the above faults, the engine must be partly dismantled and the following must he checked.
I ) Valve stuckopenduetocarbonorgumon valve stem.
‘7) Pistonringsstuck i n piston due to carbonaccumulation.Removepistonandconnectingrodfromengineand clean,correctorreplaceparts.