Troubleshooting - Subaru EX13 Service Manual

15. TROUBLESHOOTING

If the engine shows any sign of malfunction, the cause should be determined immediately and appropriate
countermeasures should be taken to prevent the problem from worsening. This section describes certain known
problems, their possible causes and appropriate countermeasures. Note, however, that the list of problems
presented here is not all. Generally speaking, since there is the possibility of multiple causes for a single problem,
please use your experience and common sense when deciding on what action to take.
15-1 ENGINE
The following three conditions must be fulfilled for satisfactory engine start.
1. The cylinder filled with a proper fuel-air mixture.
2. Good compression in the cylinder.
3. Good spark, properly timed, to ignite the mixture.
The engine cannot be started unless these three conditions are met. There are also other factors which
make engine start difficult, e.g., a heavy load on the engine when it is about to start at low speed, and a
high back pressure due to a long exhaust pipe.
1. Ignition system problems
2. Fuel system problems
3. Engine core components
problems
Problem and possible cause
1) Spark plug
・ Improper spark plug gap
・ Insulation defect
・ Carbon deposits
2) Ignition coil
・ Insulation defect or discontinuity
・ Poor contact or broken wire
3) Improper air gap between ignition coil and flywheel Adjust
1) No fuel in fuel tank
2) Fuel hose clogged or pinched
3) Air in fuel lines
4) Poor quality gasoline or water in gasoline
5) Carburetor
・ Overflow
・ Clogged or damaged
・ Throttle valve malfunction
(does not close fully)
1) Insufficient tightening of cylinder head bolts
2) Wearing of piston, piston rings and/or cylinder Repair or replace
3) Improper contact of valve and seat
4) Valve sticking
5) Improper valve clearance
6) Leakage from intake manifold gasket
7) Leakage from carburetor gasket
8) Insufficient tightening of spark plug
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Remedy
Adjust the gap
Replace
Clean
Replace
Repair or replace
Refill
Clean or replace
Check and retighten joints
Replace
Adjust
Overhaul
Check and adjust
Check and retighten
Repair
Repair
Adjust
Retighten; replace gasket
Retighten; replace gasket
Retighten