Poor Fuel Economy; Engine Runs Poorly At Idle - Mercury MerCruiser MCM 454 Mag MPI Service Manual

SERVICE MANUAL NUMBER 23

Poor Fuel Economy

Fuel leaks
Operator habits
Engine laboring
Clogged flame arrestor
Engine compartment sealed too tight
Boat bottom
Improper fuel
Crankcase ventilation system not working
Engine running too cold or too hot
Plugged or restricted exhaust
Engine

Engine Runs Poorly at Idle

Engine surges
Low top speed or lack of power
Poor cold engine operation
Engine stalls
Hard starting
Index Index
90-861326--1 MARCH 1999
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Cause
Symptoms
Special Information
Prolonged idling; slow acceleration; failure
to cut back on throttle once boat is on
plane; boat overloaded; uneven weight
distribution
Bent, damaged, or wrong propeller. Water
test boat for proper operating rpm at wide-
open-throttle
Not enough air for engine to run properly
Dirty (marine growth), hook, rocker
Low compression
Cause
Refer to "Fuel Injection Troubleshooting," j
SECTION 5D
Refer to "Engine Starts Hard"
TROUBLESHOOTING
g
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