Lycoming IO-390-D Series Maintenance Manual page 110

Problem
Engine will not start
or starts with
difficulty (Cont.)
Rough Idle
12-30
Page 84
Table 1 (Cont.)
Fault Isolation Guide
Cause
Fault in the ignition
system
Damaged or worn
ignition lead
Incorrect EIS-to-engine
timing
Magneto incorrectly
timed to engine.
Magneto internal timing
not adjusted correctly or
"E" gap drifting because
of point or follower wear.
Water in fuel system
Fault in the ignition
system
IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Corrective Action
1. Visually examine the harness for
physical damage.
2. Examine leads using a high-tension
lead tester.
3. Replace worn or damaged
components as necessary.
4. Complete the following procedures:
• Spark Plug Removal
• Ignition Harness Inspection
• Spark Plug Inspection
• Spark Plug Cleaning
• Spark Plug Gap Setting
• Spark Plug Rotation
• Spark Plug Installation
Ignition Harness Removal
Ignition Harness Inspection
Ignition Harness Installation
Refer to the "EIS Troubleshooting
Guide" in this chapter.
Complete the "Magneto-to-Engine
Timing Check."
Replace magneto with a serviceable
unit as per the "Magneto Replacement
Procedure."
Drain the fuel lines.
1. Visually examine the harness for
physical damage.
2. Examine leads using a high-tension
lead tester.
3. Replace worn or damaged
components as necessary.
4. Complete the following procedures:
• Spark Plug Removal
• Ignition Harness Inspection
• Spark Plug Inspection
• Spark Plug Cleaning
• Spark Plug Gap Setting
• Spark Plug Rotation
• Spark Plug Installation
© 2020 Avco Corporation. All Rights Reserved
Ref.
74-20
05-30
74-20
74-30
74-30
AMM
74-20
05-30
March 2020