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IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Problem
High fuel flow
Low fuel flow
* Review any applicable warranty information relative to replacement of a fuel component as per the
latest revision of Service Letters L221 and L253.
© 2020 Avco Corporation. All Rights Reserved
March 2020
Table 1 (Cont.)
Fault Isolation Guide
Cause
Blocked injection
nozzles evident by high
flow reading on pressure
type fuel flow indicator
Broken flow gage
Fuel injector rich
Dirty fuel pump filter
Faulty fuel flow gage
Fuel manifold does not
open all the way at times.
Corrective Action
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.
Install the master fuel flow gage and
operate the engine to compare gages.
or
Replace the non-conforming fuel flow
gage.
Remove the fuel injector. Either send it
to a manufacturer-approved repair
facility or replace it as per the "Fuel
Injector Replacement" procedure.*
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.
1. Install the master fuel flow gage and
operate the engine to compare gages.
2. Replace a damaged fuel flow gage.
1. Complete the "Fuel Manifold
Removal" procedure.*
2. Send to Lycoming Engines or an
authorized repair facility.
3. Complete the "Fuel Manifold
Installation" procedure.
Ref.
73-10
5-30
73-10
73-10
AMM
AMM
73-10
12-30
Page 87
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