Subaru EX13 Service Manual page 72

Problem and possible cause
1. Insufficient compression
2. Ignition system problems 1) Faulty spark plug
3. Fuel system malfunction
4. Low air intake volume
1. Engine
1. Carburetor system
2. Intake system
3. Cylinder head
4. Valve system
5. Ignition system
1) Loosen spark plug
2) Leakage from cylinder head gasket
3) Piston ring seizure or wear
4) Piston or cylinder wear
5) Incorrect valve and seat contact
6) Valve stem seizure
7) Improper valve clearance
2) Faulty ignition coil
3) Improper air gap between ignition coil and
flywheel
4) Demagnetization (flywheel magneto)
1) Carburetor clogged
2) Fuel strainer and/or hose clogged
3) Air in fuel lines
4) Poor quality gasoline or water in gasoline
1) Air cleaner clogged
2) Throttle valve malfunction
1) Cooling air flow obstructed at inlet or cylinder
baffle portion
2) Poor quality engine oil
3) Lean fuel/air mixture
4) Excessive back pressure of exhaust system
5) Overloading
1) Low idling speed
2) Slow system passage clogged
1) Air mixing from air intake system joints
1) Gasket faulty (blow-by)
1) Improper valve clearance
2) Leakage from valve seat
3) Excessive clearance between valve stem and
guide
1) Weak spark
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Remedy
Retighten; replace gasket
Retighten; replace gasket
Replace
Repair or replace
Repair or replace
Repair or replace
Adjust
Replace
Replace
Adjust
Replace
Overhaul, clean
Clean or replace
Check and retighten joints
Replace
Clean or replace
Repair or replace
Clean
Replace
Check and adjust
carburetor
Check and clean or replace
Adjust to rated load
Adjust
Check and clean
Check and tighten;
replace gasket
Replace
Adjust
Repair
Replace
Check; adjust or replace
plug