Audi Workshop Service and Repair Manuals

Checking system pressure and residual pressure   Note The fuel pressure regulator is located in the fuel filter below the fuel tank. Special tools and workshop equipment required

t  K-Jetronic pressure tester -V.A.G 1318-   Note t  Fuel pump relay OK. t  Fuel pump OK; checking: → Fuel supply system, petrol engines; Repair group 20. t  Fuel filter OK. t  Battery voltage at least 12.7 V t  Vehicles with automatic gearbox: selector lever in position P or N Checking system pressure –  Briefly open fuel tank filler cap (to release pressure). –  Remove engine cover panel.   WARNING The fuel system is pressurised. Before opening the system place a cloth around the connection. Then release pressure by carefully loosening the connection.

–  Open the union -1- and catch escaping fuel with a cloth. –  Connect K-Jetronic pressure tester -V.A.G 1318- with adapters 1318/6 and 1318/7 to fuel supply pipe.

–  Open cut-off valve on K-Jetronic pressure tester -V.A.G 1318-. Lever must point in direction of flow. –  Start the engine and run at idling speed. –  Measure the fuel pressure. t  Specification: approx. 4.0 bar –  Switch off ignition. –  Check leak-tightness and residual pressure by watching the drop in pressure on the pressure gauge. t  After 10 minutes there should still be a pressure of at least 2.5 bar. If the residual pressure drops below 2.5 bar: –  Start the engine and run at idling speed.

–  Allow pressure to build up, then switch off ignition. At the same time, close cut-off valve of K-Jetronic pressure tester -V.A.G 1318- (so that lever is perpendicular to direction of flow -arrow-). –  Observe pressure drop on K-Jetronic pressure tester -V.A.G 1318-. If the pressure drops again: –  Check K-Jetronic pressure tester -V.A.G 1318- for leaks. –  Check pipe connections, O-rings on fuel rail and injectors for leaks. If the pressure now does not drop: –  Check pressure regulator in fuel filter. Vehicles with four-wheel drive: –  Remove rear seat bench → Rep. gr.72.

–  Detach cover for flange (left-side) -arrows-.

–  Disconnect fuel return pipe -arrows- from flange (left side of vehicle).

–  Connect adapter hose -V.A.G 1318/17-1- to return pipe. –  Clamp off adapter hose using hose clamp up to 25 mm -3094-.   Note Do not attach hose clamp up to 25 mm -3094- directly to fuel pipe - risk of damage. –  Start the engine and run at idling speed.

–  Allow pressure to build up, then switch off ignition. At the same time, close cut-off valve of K-Jetronic pressure tester -V.A.G 1318- (so that lever is perpendicular to direction of flow -arrow-). –  Observe pressure drop on pressure gauge. If the pressure drops again: –  Check fuel pump non-return valve. If the pressure now does not drop: –  Replace fuel filter → Fuel supply system, petrol engines; Repair group 20 If the pressure drops again: –  Test pressure gauge for leaks.   Note t  Before detaching pressure gauge, dissipate fuel pressure by opening cut-off valve. When doing so, hold vessel in front of connection. t  Assemble the fuel supply system in reverse order. Vehicles with front-wheel drive: –  Detach trim in luggage compartment. –  If necessary, fold forward right backrest of rear seat bench.

–  Detach cover for flange (left-side) -arrows-.

–  Detach fuel return pipe -2- from flange. –  Connect adapter hose -V.A.G 1318/17-1- to return pipe. –  Clamp off adapter hose using hose clamp up to 25 mm -3094-.   Note Do not attach hose clamp up to 25 mm -3094- directly to fuel pipe - risk of damage. –  Start the engine and run at idling speed.

–  Allow pressure to build up, then switch off ignition. At the same time, close cut-off valve of K-Jetronic pressure tester -V.A.G 1318- (so that lever is perpendicular to direction of flow -arrow-). –  Observe pressure drop on pressure gauge. If the pressure drops again: –  Check fuel pump non-return valve. If the pressure now does not drop: –  Replace fuel filter → Fuel supply system, petrol engines; Repair group 20   Note t  Before detaching pressure gauge, dissipate fuel pressure by opening cut-off valve. When doing so, hold vessel in front of connection. t  Assemble the fuel supply system in reverse order.