Mercury 225 EFI, Service Manual

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FUEL INJECTION
90-884294 Page 3B-39 OCTOBER 2001
Condition Possible Source Action
Engine Idles Rough (May Lean
Sneeze) – Acceleration OK; Full
Throttle Ok. (continued) – Ignition Coil Failure.
– Broken Reed.
Refer to Section 2A Electrical
and Ignition Tests.
Inspect Reed Assembly
Engine Runs but Slowly Drops
RPM then Dies. – Restrictions in Fuel System
between Tank and Engine.
– Clogged Final Filter.
– Pulse Fuel Pump Failure.
– Electric Fuel Pump Delivery
Failure.
Install remote gas tank with
fresh, high quality fuel.
Perform Final Filter Check.
Follow Low Pressure Fuel Route
Flow Chart.
Follow High Pressure Fuel Route
Flow Chart.
Engine Stops for No Apparent
Reason or Does Not Start. – Battery Undercharged.
– EFI Harness Connections.
– Ignition System Failure.
– Pulse Fuel Pump Failure.
– Electric Fuel Pump Failure.
– ECM Failure.
Check battery connections, un-
der charged battery or worn out
battery.
Check EFI harness connector for
improper connection.
Refer to Section 2A Electrical
and Ignition Tests.
Follow Low Pressure Fuel Route
Flow Chart.
Follow High Pressure Fuel Route
Flow Chart.
The DDT (91-823686T2) will
monitor information coming from
sensors or switches to the ECM
and will indicate if the sensor or
switch is defective. For a more
thorough analysis of the ECM,
refer to EFI Tester Manual
91-11001A2.
Engine Stops for No Apparent
Reason, but will Restart. – Restriction in Fuel System Check fuel pressure on fuel rail
at the RPM that failure occurs.
*R.F.I. Radio Frequency Interference. High voltage can alter signals ECM receives from sensors causing im-
proper fuel delivery. Route all sensor wires away from high voltage leads (i.e. spark plug leads)