Mercury 305 CID, Service Manual, Page: 599 / 967

90-823225--1 1096 5E-58 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
Engine Cranks but Will Not Run Chart A-3 (1 of 4)
INJ/ECM/KS
MODULE FUSE
10A
DIST. REFERENCE
“HIGH”
BYPASS
DIST. REFERENCE
“LOW”
IGNITION CONTROL
CIRCUIT DESCRIPTION:
This chart assumes that battery condition and engine
cranking speed are OK, and there is adequate fuel in
the tank.
TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the
diagnostic chart.
1. An ECT sensor that indicates coolant tempera-
ture less than actual temperature can flood the
engine with fuel. An ECT sensor that indicates
coolant temperature greater than actual can
starve the engine of fuel. If the TP sensor is at 50
to 75% of its range, the engine may be in the clear
flood mode, which will cause starting problems.
The engine will not start without reference pulses
and, therefore, the scan tool should read engine
RPM (reference) during cranking.
2. No spark may be caused by one of several com-
ponents related to the high energy ignition/IC
system. The ignition system will address all prob-
lems related to the causes of a no spark condi-
tion.
3. The test light should blink, indicating the ECM is
controlling the injectors OK.
4. All injectors should be within 1.0 ohm of each oth-
er and should not be less than 12 ohms at 70
°
F
(21
°
C). If an injector is suspected for a no start
condition, unhook the suspected injector and try
to start the engine.
5. Use fuel pressure gauge 91-16850 or J-34730-1.
Wrap a shop towel around the fuel pressure tap
to absorb any small amount of fuel leakage that
may occur when installing the gauge.
DIAGNOSTIC AIDS:
•
Unless engine enters “Clear Flood” at the first in-
dication of a flooding condition, it can result in a
no start.
•
Check for fouled plugs.
•
Water or foreign material in fuel line, VST, water
separating fuel filter can cause a no start in cold
weather.
•
A defective MAP sensor may cause a no start or
a stall after start. To determine if the sensor is
causing the problem, disconnect it. The ECM will
then use a default value for the sensor, and if the
condition is corrected and the connections are
OK, replace the sensor.
•
Using injector harness test light (J-34730-2A)
check for blinking light at injector harness on both
banks of the engine. If not OK, check injector
fuses.
If above are all OK, refer to “Troubleshooting.”