Kohler Command PRO ECH630 Service Manual page 53

Figure 5-18. Pulse and Mechanical Fuel Pump.
The fuel pump module is rated for a minimum output
of 13.5 liters per hour and regulated at 270 kilo pascals
(39 psi).
When the key switch is turned ON and all safety
switch requirements are met, the ECU activates the
fuel pump module for about six seconds, 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 aft er 4 cranking revolutions if
system function is OK. Once the engine is running, the
fuel pump remains on.
Service
The fuel pump module is not serviceable and must
be replaced if determined to be faulty. If a fuel pump
problem is suspected, make certain the pump is
being activated, 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 may be conducted.
1. Relieve fuel pressure at the fuel pump module
following the instructions on page 5.2. The fuel
pump module may need to be loosened or pulled
away from the engine. Disconnect the fuel
coupler from the fuel pump module and insert
the pressure test jumper (from Kohler EFI Service
Kit) between the high pressure fuel line and the
fuel pump module.
2. Connect the black hose of Pressure Tester (part of
EFI Service Kit, see Section 2). Route the clear
hose into a portable gasoline container or the
equipment fuel tank.
3. Turn on the key switch to activate the pump and
check the system pressure on the gauge. It may
take several key cycles to compress the air
introduced into the system and reach regulated
pressure. If system pressure of 39 psi ± 3 is
observed, the wiring, fuel pump, and regulator
are working properly. Turn key switch OFF and
depress the valve butt on on the tester to relieve
the system pressure.
a. If the pressure is too high, replace the fuel
pump module.
b. If the pressure is too low, replace the fuel
pump module.
4. If the pump did not activate (step 3), disconnect
the plug from the fuel pump. Connect a DC
voltmeter across the terminals in the plug, turn
on the key switch and observe if a minimum of 7
volts is present during the six second prime
process.
5. If no voltage is observed, connect the red lead of
meter to the red wire of the plug and the black
lead to a good ground while the key is still ON.
Section 5
EFI Fuel System
5.21
5