6-32
ENGINE PRIMARY SYSTEMS
TROUBLESHOOTING
Use the following troubleshooting guide to locate
problems with the engine primary systems. Many of
the primary systems can be serviced without re-
moving the genset from the vehicle.
Poor engine performance is often caused by a dirty
carburetor. Make certain that the carburetor is
clean before troubleshooting for performance prob-
lems.
WARNING
Many troubleshooting procedures present hazards that can result in severe personal inju-
ry or death. Only qualified service personnel with knowledge of fuels, electricity, and machinery haz-
ards should perform service procedures. Review safety precautions on page iii.
TABLE 6-15. TROUBLESHOOTING ENGINE PRIMARY SYSTEMS
Trouble Possible Cause Corrective Action Section/
Page
Engine Runs 1. Dirty air or fuel filter. 1. Check and replace if necessary.
Rough:
2. Contaminated fuel. 2. Drain fuel tank, clean the fuel system
and refill with fresh fuel.
3. Lean fuel mixture due to:
a. Incorrectly adjusted 3a. Adjust carburetor main 8-14
Fuel mixture screws. and idle adjustment screws.
b. Dirt in carburetor. 3b. Disassemble carburetor and clean 8-15
c. Vacuum leak. all internal passages. Replace filter.
3c. Locate and correct leak.
d. Gasket failure. 3d. Replace gasket.
4. Faulty ignition due to:
a. Worn or fouled spark plug. 4a. Replace spark plug.
b. Poor magneto or coil connections. 4b. Check magneto and coil connections.
c. Faulty ignition components. 4c. Perform Ignition Spark Check. 8-6
d. Faulty plug wire. 4d. Check spark plug wire and boot.
e. Incorrect ignition timing. 4e. Rotor or fan hub improperly installed.
Engine 1. Lean fuel mixture due to: 1a. Adjust carburetor main and idle 8-14
Backfires a. Incorrectly adjusted fuel mixture screws.
Through adjustment screws. 1b. Disassemble carburetor and clean 8-15
Carburetor b. Dirt in carburetor. all internal passages.
c. Vacuum leak. 1c. Locate and correct leak.
2. Mechanical engine defect 2. Perform Leak Down Test. 10-1
(intake valve defect).
3. Faulty ignition due to: 3. Reset spark plug gap.
incorrect spark plug gap.
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