Audi Workshop Service and Repair Manuals

Checking fuel pressure and residual pressure (up to high-pressure pump) Special tools and workshop equipment required

t  K-Jetronic pressure tester -V.A.G 1318- t  Fuel-resistant measuring container Test conditions l  Battery voltage at least 12.5 V. l  Fuel filter OK. l  Fuel tank at least 1/4 full. l  Fuel pump control unit -J538- OK (check) l  Ignition off. Test sequence   WARNING The fuel system is pressurised (initial fuel pressure). Wear safety goggles and protective clothing to avoid possible injury and skin contact. Wrap a cloth around the connection before opening the fuel system. Then dissipate residual pressure by carefully detaching the connection.

–  Lift release tab and disconnect fuel supply pipe -arrow-. –  Screw connector -V.A.G 1318/23- and adapter set -V.A.G 1318/17A- onto K-Jetronic pressure tester -V.A.G 1318-.

–  Fit adapter set -V.A.G 1318/17A- onto the disconnected fuel supply line. –  Run test hose into measuring glass -arrow-.

–  Close cut-off valve on K-Jetronic pressure tester -V.A.G 1318-. Lever is at right angle to direction of flow -arrow-. –  Connect a vehicle diagnostic tester. –  Press buttons on touch screen for »Vehicle self-diagnosis«, then »Engine electronics«, then »Final control diagnosis«. –  Press right-hand arrow button on touch screen until tester advances to final control diagnosis of fuel pump electronics. –  The fuel pump should start running. –  Read off fuel pressure on K-Jetronic pressure tester -V.A.G 1318-. l  Specification: approx. 6 bar (3 ... 7 bar). If specification is not obtained: –  Check delivery rate of fuel pump → Fuel supply system, petrol engines; Rep. gr.20. Checking residual pressure –  Check system for leaks and check residual pressure by watching the drop in pressure on the K-Jetronic pressure tester -V.A.G 1318-. l  After 10 minutes pressure should still be at least 3 bar. If the residual pressure drops below 3 bar: t  Check union between K-Jetronic pressure tester -V.A.G 1318- and fuel supply line for leaks. t  Check K-Jetronic pressure tester -V.A.G 1318- for leaks. t  Check fuel lines and their connections for leaks. t  Renew fuel filter with integrated fuel pressure regulator → Fuel supply system, petrol engines; Rep. gr.20. Then repeat the test. t  If fuel filter is OK, renew fuel pump → Fuel supply system, petrol engines; Rep. gr.20. Assembly is carried out in the reverse order; note the following: –  The ignition must be switched off.   Note

Before removing the pressure tester, release the fuel pressure by opening the cut-off valve. Hold end of test hose into measuring container -arrow-.

–  Re-attach fuel supply line -arrow- (make sure that all parts are clean and that there are no leaks).