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5B.19
Section 5B
EFI Fuel System
5B
Figure 5B-24. “24 Pin” (MSE 1.0) Plastic-Cased
ECU Connector.
Fuel Components
Fuel Pump
Figure 5B-25. “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.
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.
Figure 5B-26. 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 page 5B.22.
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.
Service
The fuel pumps are non-serviceable and must be
replaced if determined to be faulty. If a fuel delivery
problem is suspected, make certain the pump is being
activated through the relay, all electrical connections
are properly secured, the fuses are good, and a
minimum of 7.0 volts is being supplied. If during
cranking, voltage drops below 7.0 volts, a reduction of
fuel pressure may occur resulting in a lean starting
condition. If required, testing of the fuel pump and
relay may be conducted.
Internal
External