Test 20 - Check Spark Plugs; Test 21 - Check Carburetion; Test 22 - Choke Test; Test 23 - Check Valve Adjustment - Generac Power Systems GP Series Diagnostic Repair Manual

Test 20 – Check Spark Plugs
Procedure
See Figure 4-12 and Figure
Clean with commercial solvent. Replace spark plugs if
badly fouled, if ceramic is cracked, or if badly worn or
damaged.
IMPORTANT NOTE: Do NOT blast clean spark plugs.
A B
D E
A. Normal
B. Mechanical Damage
C. Oil Fouled
Figure 4-12. Spark Plug Conditions
Figure 4-13. Setting Spark Plug Gap
Results
Clean and gap or replace sparks plug as
1.
necessary.
Refer to flow chart.
2.
Test 21 – Check Carburetion
Procedure
Before making a carburetion check, be sure fuel supply
tank has fresh, clean gasoline.
Check all shutoff valves are open and fuel flows freely
through fuel line.
Verify choke operates correctly.
If engine will not start, remove and inspect spark plug. If
spark plug is wet, look for the following:
•
Overchoking
•
Excessively rich fuel mixture
Diagnostic Repair Manual
4-13. Remove spark plugs.
C
F
013032
D. Overheated
E. Insulator Glazing
F. Pre-Ignition
000211
Section 4 Engine Diagnostic Tests
•
Water in fuel
•
Intake valve stuck open
•
Needle/float stuck open
If spark plug is dry, look for the following:
•
Leaking carburetor mounting gaskets
•
Intake valve stuck closed
•
Inoperative fuel pump
•
Plugged fuel filter(s)
•
Varnished carburetor
If engine starts hard or will not start, look for the following:
•
Physical damage to AC generator. Check Rotor for
contact with Stator.
•
Starting under load. Make sure all loads are
disconnected or turned off before attempting to
crank and start engine.
•
Be sure choke is working properly.
Remove fuel line at carburetor and ensure there is
1.
adequate fuel entering the carburetor.
Remove float bowl and check for foreign matter in
2.
bottom of carburetor bowl.
The float is plastic and can be removed for access
3.
to needle for cleaning.
With all of this removed, carburetor cleaner can be
4.
used to clean carburetor before assembly.
After cleaning carburetor with approved carburetor
5.
cleaner, blow dry with compressed air and
assemble.
Shelf life of gasoline is 30 days. A fuel stabilizer must be
used to ensure fuel is fresh at all times.
Results
If carburetor is varnished, clean or replace. Refer to flow
chart.
Test 22 – Choke Test
Procedure
If generator is surging, it may be a carburetion problem.
A lean condition can cause erratic RPM. Slowly pull
choke out to see if surging stops. If it does stop,
carburetion should be checked.
Test 23 – Check Valve Adjustment
Adjusting Valve Clearance
Improperly adjusted valves can cause various engine
related problems including, but not limited to, hard
starting, rough running and lack of power.
Adjust valve clearance with engine at room temperature.
The piston should be at top dead center (TDC) of its
compression stroke (both valves closed).
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