Mercury 225 EFI, Service Manual

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IGNITION
90-884294 OCTOBER 2001 Page 2A-23
Ignition Troubleshooting and Fault Chart
CAUTION
To protect against meter and/or component damage, observe the following pre-
cautions:
•
DO NOT reverse battery cable connections. The battery negative cable is (–)
ground.
•
DO NOT “spark” battery terminals with battery cable connections to check po-
larity.
•
DO NOT disconnect battery cables while engine is running.
Before troubleshooting the ignition system, check the following:
1. Make sure that electrical harness and ignition switch are not the source of the prob-
lem.
2. Check that plug-in connectors are fully engaged and terminals are free of corrosion.
3. Make sure that wire connections are tight and free of corrosion.
4. Check all electrical components, that are grounded directly to engine, and all ground
wires to see that they are grounded to engine.
5. Check for disconnected wires and short and open circuits.
Symptom Cause Action
1. Engine cranks but won’t
start 1.0 Lanyard stop switch in
wrong position.
Reset lanyard stop switch.
1.1 Weak battery or bad starter
motor, battery voltage drops
below 8 volts while cranking
(ECM cuts out below 8volts)
(Fuel pump requires 9volts)
Replace/charge battery.
Inspect condition of starter motor.
Check condition of battery termi-
nals and cables.
1.2 No fuel Check that primer bulb is firm. Key-
on engine to verify that fuel pump
runs for 2 seconds and then turn off.
Measure fuel pressure
1.3 Flywheel misaligned during
installation
Remove flywheel and inspect.
1.4 Blown fuse Replace fuse. Inspect engine har-
ness and electrical components.
1.5 Main Power Relay not
functioning
Listen for relay to “click” when the
key switch is turned on.
1.6 Spark Plugs Remove spark plugs from each
cylinder.
Connect spark plug leads to Spark
Gap Tester 91-830230T.
Crank engine or use DDT output
load test for each ignition coil and
observe spark. If no spark is pres-
ent, replace appropriate ignition
coil. If spark is present, replace
spark plugs.