Electra V6-260 4.3L DSL (1984)
Diesel MFI Pump: Description and Operation
The V6-262 diesel engine may be equipped with one of two fuel injection pumps: the Roosa Master which can be identified by a looped fuel inlet
pipe, and CAV pump which can be identified by a straight fuel inlet pipe.
Injection timing is controlled by two pressure regulators. One regulator is the Housing Pressure Cold Advance (HPCA), located in the pump. The
other pressure regulator, used on 1984 except California models and all 1985 models, is the Housing Pressure Altitude Advance (HPAA), located
in the fuel return line. The HPCA is designed to advance injection timing about 4° during cold operation. The HPAA will regulate housing
pressure according to altitude.
Fig. 43 Roosa Master pump solenoids and connectors location
Fig. 44 CAV pump solenoids and connectors location
The Metering Valve Sensor (MVS), used on 1984 California models and all 1985 models with Diesel Electronic Control System, is a variable
resistor which electronically signals the diesel ECM as to the position of the metering valve.
The injection pump is mounted on top of the engine. It is gear driven off the camshaft and turns at camshaft speed. It is a high pressure rotary
pump that injects a metered amount of fuel to each cylinder at the proper time. The six high pressure delivery pipes from the pump to the injection
nozzle in each cylinder are the same length to prevent any difference in timing, cylinder-to-cylinder. The fuel injection pump provides the required
timing advance under all operating conditions. Engine RPM is controlled by a rotary fuel metering valve. Pushing down on the accelerator pedal
moves the throttle cable to open the metering valve and allow more fuel to be delivered. The injection pump also has a low pressure transfer pump
