5B.16
Section 5B
EFI Fuel System
Internal
External
4.
If the secondary resistance is not within
the specified range, unscrew the spark
plug lead nut from the coil secondary
tower and remove the plug lead. Repeat
step 6, testing from the secondary tower
terminal to the red primary terminal. If
resistance is now correct, the coil is good,
but the spark plug lead is faulty, replace
the lead. If step 5 resistance was incorrect
and/or the secondary resistance is still
incorrect, the coil is faulty and needs to be
replaced.
Spark Plugs
EFI engines require resistor spark plugs. Do not try to
substitute non-resistor plugs.
Wiring Harness
The wiring harness used in the EFI system connects
the electrical components, providing current and ground
paths for the system to operate. All input and output
signaling occurs through a special all weather
connector that attaches and locks to the ECU (see
Figure 5B-19).
Battery Charging System
EFI engines are equipped with either a 15 or 25 amp
charging system to accommodate the combined
electrical demands of the ignition system and the
specific application. Charging system troubleshooting
information is provided in Section 8.
Fuel Components
Fuel Pump
Figure 5B-19. “32 Pin” (MSE 1.1) Plastic-Cased ECU
Connector.
The condition of the wiring, connectors, and terminal
connections is essential to system function and
performance. Corrosion, moisture, and poor
connections are more likely the cause of operating
problems and system errors than an actual component.
Refer to the ‘‘Troubleshooting – Electrical’’ section for
additional information.
Figure 5B-20. Fuel Pump Styles.
General
An electric fuel pump is used to transfer fuel in the EFI
system. Depending on the application, the pump may
be inside the fuel tank, or in the fuel line near the tank.
The pumps are rated for a minimum output of 25 liters
per hour at 39 psi. The pumps have an internal
60-micron filter. In addition, the in-tank style pumps will
have a pre-filter attached to the inlet. In-line pump
systems may also have a filter ahead of the pump on
the pick-up/low pressure side. The final filter is covered
separately on pages 5B.18 and 5B.19.
When the key switch is turned “on” and all safety
switch requirements are met, the ECU, through the
relay, activates the fuel pump, which pressurizes the
system for start-up. If the key switch is not promptly
turned to the “start” position, the engine fails to start, or
the engine is stopped with the key switch “on” (as in
the case of an accident), the ECU switches off the
pump preventing the continued delivery of fuel. In this
situation, the MIL will go on, but it will go back off after
4 cranking revolutions if system function is OK. Once
the engine is running, the fuel pump remains on.
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