Troubleshooting; Troubleshooting Guide; Fuel System - Kohler Command PRO ECH630 Service Manual

Section 5
EFI Fuel System

Troubleshooting

General
When troubleshooting a problem on an engine
with EFI, basic engine operating problems must
be eliminated fi rst before faulting the EFI system
components. What appears to be an EFI problem
could be something as simple as a fuel tank with
debris in the bott om or a plugged vent. Be sure the
engine is in good mechanical operating condition
and all other systems are operating properly before
att empting to troubleshoot the EFI system.

Troubleshooting Guide

Engine starts hard or fails to start when cold
1. Fuel pump not running
2. Faulty spark plugs
3. Old/stale fuel
4. Incorrect fuel pressure
5. Crankshaft position sensor loose or faulty
6. TPS set incorrect (ECU Reset and TPS Learn)
7. TPS faulty
8. Engine temp sensor faulty
9. Faulty coils
10. Low system voltage
11. Faulty injectors
12. Faulty batt ery
13. Loose or corroded connections
Engine starts hard or fails to start when hot
1. Faulty spark plugs
2. Fuel pump not running
3. Fuel pressure low
4. Insuffi cient fuel delivery
5. TPS set incorrect (ECU Reset and TPS Learn)
6. Crankshaft position sensor loose or faulty
7. TPS faulty
8. Engine temp sensor faulty
9. Faulty injectors
Engine stalls or idles roughly (cold or warm)
1. Faulty spark plugs
2. Insuffi cient fuel delivery
3. TPS set incorrect
4. TPS faulty
5. Faulty engine temperature sensor
6. Faulty injectors
5.26
Engine misses, hesitates, or stalls under load
1. Fuel injector(s), fuel fi lter, fuel line, or fuel
pick-up dirty/restricted
2. Dirty air cleaner
3. Insuffi cient fuel pressure or fuel delivery
4. Vacuum (intake air) leak
5. Improper governor sett ing, adjustment or
operation
6. TPS faulty, mounting problem or TPS Learn
Procedure incorrect
7. Bad coil(s), spark plug(s), or wires
Low Power
1. Faulty/malfunctioning ignition system
2. Dirty air fi lter
3. Insuffi cient fuel delivery
4. Improper governor adjustment
5. Plugged/restricted exhaust
6. One injector not working
7. Basic engine problem exists
8. TPS faulty or mounting exists
9. Thrott le plate in thrott le body not fully opening
to WOT stop (if so equipped)

Fuel System

WARNING: Fuel System Under Pressure!
The fuel system operates under high pressure. System
pressure must be relieved through the fuel connector and
the fuel pump module (see page 5.2) prior to servicing or
removal of any fuel system components. Do not smoke
or work near heaters or other fi re hazards. Have a fi re
extinguisher handy and work only in a well-ventilated area.
The function of the fuel system is to provide suffi cient
delivery of fuel at the system operating pressure of
39 psi ± 3. If an engine starts hard, or turns over but
will not start, it may indicate a problem with the EFI
fuel system. A quick test will verify if the system is
operating.
1. Disconnect and ground the spark plug leads.
2. Complete all safety interlock requirements and
crank the engine for approximately 3 seconds.