Problem Diagnosis - Mercury 150 EFI Service Manual

Problem Diagnosis

Condition
Engine Down On Power Or RPM – Failed Ignition Coil
Poor Acceleration – Idles Ok,
Top Speed Ok
90-883728 JULY 2001
Possible Source
– Low Compression
– Broken Reed
– Fuel Delivery Problem
– Fuel Rail Leak
– Vapor Separator Flooding
Over, Engine Running Rich.
– Cylinder Head Temperature
Sensor Circuit Failed.
– Improper EFI Set Up.
– Water Covering Idle Relief
Exhaust Ports.
– T.P.S. Failure.
– MAP Sensor Failure
– R.F.I. Problem*
FUEL INJECTION
Action
Refer to Section 2 Electrical and
Ignition Tests.
Refer to Section 4 Power Head.
Inspect Reeds.
Follow Low/High Pressure Fuel
Route Flow Charts and Fuel Rail
Electrical/Fuel Determination
Flow Chart.
Perform Fuel Rail Leak Test.
Check for fuel coming out of va-
por separator vent hose.
Check cylinder head temperature
sensor.
Refer to Section 2 Electrical and
Ignition for proper EFI set up pro-
cedures.
Boats with extended transoms or
low engine mount can cause en-
gine to load up on acceleration.
Refer to page 3B-33.
Refer to page 3B-34.
Install BPZ8HS-10 Spark Plugs.
Page 3B-35