Audi A4, S4

since 2000 release

Repair and operation of the car

Dropping pressure in fuel system

Before getting to work, examine the precautionary measures given in the section General information and security measures.

After performance of the procedure described below you will only remove excessive pressure in fuel system. In pipelines there will be a gasoline. Before disconnecting any fuel hose, take all necessary precautionary measures.

The fuel system considered in this Chapter consists of the fuel tank located in it the fuel pump with the sensor of a reserve of fuel, the fuel filter, injectors or nozzles, the regulator of pressure and various hoses and tubes. In all these knots in engine operating time (and also at the included ignition) fuel is under pressure.

After ignition switching off pressure in system remains still quite long time. Before a detachment of any of mentioned above a component pressure it is necessary to remove.

For this purpose quickly open a cover of a fuel tank and again close it. Put a thick rag on connection. Use goggles. In system of direct injection of the AWA engine by the described image pressure only regarding the system having low pressure (to 6 atm can be removed.). For removal of a high pressure (to 110 atm.) special devices are required. The high pressure in system is present at area from TNVD to nozzles. At the diesel engine of 1.9 l temperature of fuel pipelines and fuel at the engine about the pump nozzles in extreme cases can make to 100 °C. Before opening of connections, let's fuel cool down since otherwise it can occur a burn.

The simplest way of dumping of pressure is following. Take a safety lock of the fuel pump and start the engine. If the engine is not started, turn it a starter within several seconds and if it is started, allow the engine to work at single turns until he does not decay. Completely to dump pressure, turn the engine crankshaft a starter on couple of turns. Switch off ignition and return into place a pump safety lock.

Keep in mind that if pressure is dumped (or fuel is removed from system), start of the engine will borrow bigger, than usually, time. You should turn the engine crankshaft a starter at least some seconds during which pressure in system will be restored, and fuel will fill all pipelines.