IO-390-D Series Engine Maintenance Manual
© 2020 Avco Corporation. All Rights Reserved
12-30
March 2020
Page 87
IO-390-D Series Engine Maintenance Manual
Table 1 (Cont.)
Fault Isolation Guide
Problem
Cause
Corrective Action
Ref.
High fuel flow
Blocked injection
nozzles evident by high
flow reading on pressure
type fuel flow indicator
1.
Complete an “Injection Nozzle Fuel
Flow-Check.”
2.
Complete the “Injection Nozzle
Removal” procedure.
3.
Complete the “Injection Nozzle
Cleaning” procedure.
4.
Complete the “Injection Nozzle
Installation” procedure.
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5-30
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Broken flow gage
Install the master fuel flow gage and
operate the engine to compare gages.
or
Replace the non-conforming fuel flow
gage.
Fuel injector rich
Remove the fuel injector. Either send it
to a manufacturer-approved repair
facility or replace it as per the “Fuel
Injector Replacement” procedure.*
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Low fuel flow
Dirty fuel pump filter
Remove and clean the fuel pump filter
with acetone or MEK, blow out with
compressed air, and re-install the fuel
pump filter
or
Replace the fuel pump filter.
AMM
Faulty fuel flow gage
1.
Install the master fuel flow gage and
operate the engine to compare gages.
2.
Replace a damaged fuel flow gage.
AMM
Fuel manifold does not
open all the way at times.
1.
Complete the “Fuel Manifold
Removal” procedure.*
2.
Send to Lycoming Engines or an
authorized repair facility.
3.
Complete the “Fuel Manifold
Installation” procedure.
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* Review any applicable warranty information relative to replacement of a fuel component as per the
latest revision of Service Letters L221 and L253.