TP-6903 5/16a Fuel System Overview 11
Section 1 Fuel System Overview
1.1. Introduction
The KG2204 and KG2204T are four-stroke internal
combustion engines certified to operate on Natural Gas
(NG) or Liquefied Petroleum Gas (LPG). System
configuration is factory preset for NG and can be reset
for LPG applications.
At startup, the engine ECM operates in an open-loop
fuel state, which means fuel delivery is based on a fuel
calibration program internal to the ECM. The program
controls the fuel control valve to achieve stoichiometric
combustion.
After the oxygen sensor heats up and the engine
coolant temperature reaches a predetermined level,
the ECM calibration program transitions to a closed-
loop mode. The air/fuel delivery is based on the
oxygen sensor input and engine sensor data. The
engine ECM uses this data to regulate the fuel control
valve (FCV), which is used as a fuel trim device and is
located at the intake manifold. The FCV is an
electrically controlled engine vacuum switch. When
the FCV is energized, the valve opens and, through a
vacuum line connection to the fuel regulator, creates a
vacuum on the fuel pressure regulator. This vacuum
causes the regulator’s diaphragm to close, decreasing
the fuel delivered to the intake. The FCV signal would
be considered a modulated signal sent by the ECM to
obtain stoichiometric combustion.
Figure 1-1 Fuel System Overview, KG2204 Naturally Aspirated Engine
1. HEGO sensor
2. TMAP sensor
3. Fuel control valve
4. Throttle body
5. Air-fuel mixer
6. Coolant temperature sensor
7. Crankshaft position sensor
8. Exhaust
9. Ignition coil
10. Oil pressure sender
11. Fuel pressure regulator
12. Fuel shut-off valve
13. ECM
14. Air cleaner
15. Air intake
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