GF83.70-D-4203HS STH Fuel Metering Pump, Component Description

GF83.70-D-4203HS STH Fuel Metering Pump, Component Description
MODEL 906.111 /113 /131 /133 /135 /153 /155 /211 /213 /231 /233 /235 /253 /255 /611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735
- with CODE (H12) Warm water auxiliary heater

MODEL 906.611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735
- with CODE (HZ5) 10 kW warm water auxiliary heater with timer







1 Stationary heater unit
M46/1 Metering pump
N33/3 Warm water additional heater control unit

Location
The metering pump is incorporated in the stationary heater (STH) fuel feed line and is located next to the stationary heater unit, which is located at the vehicle underside between the left vehicle rocker panel and the vehicle tank at the level of the B-pillar.

Task
The metering pump supplies the fuel via the fuel feed line from the fuel tank to the stationary heater unit depending on the power output stage of the stationary heater unit and closes the fuel feed line when the stationary heater unit is switched off.

Design
The metering pump is a reciprocating piston pump and consists of the following components:
- Solenoid
- Check valve
- Feed chamber
- Return spring
- Anchor with piston
- Suction valve
- Bellows damper

Function
The metering pump is controlled via the particular frequency applied by the warm water auxiliary heating control unit.
By energizing the solenoid, the fuel in the feed chamber is delivered into the fuel feed line to the stationary heater unit against the hydraulic resistance via the check valve. After approximately t = 40 ms, the solenoid is no longer energized, the return spring presses the anchor with piston back and the feed chamber is filled with fuel again via the fuel feed line from the fuel tank via the replenishing valve. The bellows damper reduces the vibrations of the anchor with piston within the metering pump generated due to the actuation of the solenoid.