DFI fuel low pressure circuit function

P07.13-0349-76

Design

13 Fuel pump (vane cell delivery pump)

13/7 Pressure control valve

15/1 Overflow valve with restrictor

60 Fuel heat exchanger

70/2 Fuel full-flow filter

70/7 Filter head

80 Fuel tank

90/1 Suction pipe to fuel heat exchanger

90/3 Fuel return pipe for leak fuel

90/4 Fuel feed pipe

90/5 Fuel return pipe

Y23/3 DFI distributor-type injection pump

A Coolant from cylinder head

B Coolant to heat exchanger
(car heater)

Task

Supplying an adequate quantity of filtered fuel from the fuel tank in all operating conditions and at a sufficient pressure to the distributor injection pump (Y23/3).

Function

The integrated fuel pump (13) draws the fuel through the fuel heat exchanger (60) and the fuel full-flow filter (70/2). An overflow valve with restrictor (15/1) and bypass drilling ensures adequate breathing.

The excess fuel supply by the fuel pump flows from the interior of

the distributor injection pump (Y23/3) through the overflow valve with restrictor (15/1) into the fuel return pipe (90/5). The leak fuel from the injection nozzles (51) also flows into the fuel return pipe (90/5) and from there flows back pressureless to the fuel tank (80). As a result of this circulation relatively cool fuel is always available for the distributor injecion pump (Y23/3).

Note

At least one injection pipe must be briefly opened for restarting or if the fuel tank has been run empty.