Fuel Supply, Basic Function - GF47.00-P-1003A
Engine all (4xWD)
Engine all (CAR)
Example illustration of low-pressure fuel circuit and high-pressure fuel circuit (spark-ignition engine)
Overview
This document contains information on:
- General
- Function requirements
- Function
- Low-pressure fuel circuit, function
- Function sequence for fuel low-pressure circuit
General
The fuel supply system (low-pressure fuel circuit) provides fuel from the fuel tank for mixture formation under all operating conditions.
Function requirements
- Engine management ON (circuit 87M)
- Ignition ON (circuit 15)
Function
Low-pressure fuel circuit, function
The fuel supply for mixture formation is provided via the low-pressure fuel circuit.
The low-pressure fuel circuit essentially consists of the following components:
- Fuel tank
- Fuel feed module
- Fuel temperature sensor
- Fuel pressure and temperature sensor
- Fuel pump control unit
- Fuel filter module (for diesel engines)
- Fuel preheating control unit (for diesel engines)
The fuel is delivered from the fuel tank to the high-pressure fuel pump by the fuel delivery module with integrated fuel pump.
In spark-ignition engines, a fuel filter is integrated in the fuel delivery module to hold back impurities. There is a check valve at the feed point of the fuel filter which prevents reduction of the fuel pressure when the fuel pump is switched off.
In diesel engines, the fuel filter is in the fuel filter module between the fuel delivery module and the high-pressure fuel pump. In diesel engines, the fuel filter module has the following tasks:
- Retardation of impurities in the fuel.
- Separating condensation.
- Fuel preheating.
Depending on the fuel requirements, the fuel pressure is variably regulated to approx. 4.0 to 6.7 bar by the pressure limiting valve. The quantity control valve regulates the feed quantity in line with demand.
This avoids excessive heating of the fuel. The fuel temperature can be kept low as a result.
Function sequence for fuel low-pressure circuit
The fuel pump is switched on as soon as the signal "fuel pump ON" is received by the fuel system control unit.
The fuel system control unit ascertains the fuel pressure through a voltage signal from the fuel pressure sensor and compares the actual pressure with the specified pressure. The fuel pump is actuated by the fuel system control unit via a pulse width modulated signal. In this way, the fuel specified pressure and the delivery rate are adapted to the current fuel requirements.
In order to determine the fuel specified pressure, the combustion engine control unit evaluates the actual fuel pressure and the load requirements. The evaluated information is passed on to the fuel system control unit.
The fuel temperature is constantly recorded and transmitted to the combustion engine control unit.
| Function schematics | |||
| Function schematic for fuel supply system | Engine 608 in model 118, 177, 247 | PE47.00-P-2500-97A | |
| Engine 654 in model 118, 167, 177, 247 Engine 654 in model 213, 238, 257 as of model year 2021 Engine 656 in model 167 | PE47.00-P-2500-97B | ||
| Engine 139 in model 118, 177, 247 Engine 256 in model 213, 238 as of model year 2021 Engine 256, 264 in model 167 Engine 260, 282 in model 118, 177, 247 Engine 264 in model 213, 238, 257 as of model year 2021 | PE47.00-P-2500-97C | ||
| Engine 176, 177 in model 167 Engine 177 in model 290 as of model year 2021 | PE47.00-P-2500-97D | ||
| Engine 279 in model 223 | PE47.00-P-2500-97E | ||
| Engine 254 in model 206, 254 Engine 256 in model 223 | PE47.00-P-2500-97F | ||
| Engine 176 in model 223 | PE47.00-P-2500-97G | ||
| Engine 139 in model 206, 232 | PE47.00-P-2500-97H | ||
| Engine 654 in model 206, 254 Engine 656 in model 223 | PE47.00-P-2500-97I | ||
| Engine 177 in model 223, 232 | PE47.00-P-2500-97J | ||
| Engine 274 in model 213 as of model year 2021 | PE47.00-P-2500-97K | ||
| Engine 656 in model 464 | PE47.00-P-2500-97L | ||
| Additional basic functions | |||
| Fuel system control unit, basic function | GF47.40-P-9890A | ||
| Fuel tank, basic function | GF47.10-P-2001A | ||
| Detailed information | |||
| Fuel supply system, detailed information | Engine 608, 654, 656 | GF47.00-P-1100A | |
| Engine 656 | |||
| Engine 176, 177, 254, 256, 260, 264, 274, 279 | GF47.00-P-1100B | ||
| Engine 139 | GF47.00-P-1100D |