Lycoming IO-390-D Series Maintenance Manual page 116

Problem
Engine will not turn
static rpm or will not
develop rated rpm
(Cont.)
Engine hesitates,
misses
Engine surges
* Review any applicable warranty information relative to replacement of a fuel component as per the
latest revision of Service Letters L221 and L253.
12-30
Page 90
Table 1 (Cont.)
Fault Isolation Guide
Cause
Incorrect EIS-to-engine
timing
Incorrect magneto-to-
engine timing
Incorrect internal engine
timing
Fuel injector clogged
Blockage in manifold
system
Leak in engine intake or
exhaust
Fault in the ignition
system
Lycoming Electronic
Ignition System (EIS)
Valve sticking
Injection nozzles are
dirty
Fuel injector
malfunction
IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Corrective Action
Refer to the EIS Troubleshooting
Guide in this chapter.
Complete the "Magneto-to-Engine
Timing Check."
Complete a check of the internal
engine timing and adjust as necessary
Replace the clogged fuel injector* per
the "Fuel Injector Replacement"
procedure.
Clear all ducting.
Tighten loose connections or replace
manifold gaskets as necessary.
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
Refer to the "EIS Troubleshooting
Guide" in this chapter
Refer to "Corrective Action for Valve
Sticking."
Complete the "Injection Nozzle
Cleaning" procedure.
Replace the fuel injector* per the "Fuel
Injector Replacement" procedure.
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Ref.
74-30
72-20
73-10
74-20
05-30
72-30
05-30
73-10
March 2020