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