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  Adapter -V.A.G 1318/11- t  Adapter -V.A.G 1318/12-

t  Remote control -V.A.G 1348/3A- for V.A.G 1348 with adapter cable -V.A.G 1348/3-3- t  Fuel-resistant measuring container

Test conditions: l  Battery voltage at least 12.5 V l  Fuse in fuse holder -S228- (position 28) OK.

l  Fuel pump control unit -J538- OK (check) l  Fuel filter OK l  Fuel tank at least 1/4 full. Test sequence –  Switch off ignition. Saloon: –  Detach trim in luggage compartment. –  If necessary, fold forward right backrest of rear seat bench. Avant: –  Remove left-side section of backrest (1/3 section) → Rep. Gr.72. –  Remove left-side trim in luggage compartment and anti-soiling tray → Rep. Gr.70.

All vehicles: –  Unscrew cover for flange -arrows-.

–  Unplug electrical connector -arrow- at flange.

–  Connect remote control -V.A.G 1348/3 A- with adapter cable -V.A.G 1348/3-3- to contact -1- using a test lead from auxiliary measuring set -V.A.G 1594 C-. –  Tape off 2nd connector contact of adapter cable -V.A.G 1348/3-3- with insulating tape -arrow- to prevent short circuits. –  Connect contact -4- to the body (earth) using a test lead from auxiliary measuring set -V.A.G 1594 C-. –  Connect crocodile clip to vehicle battery (positive).

–  Remove filler cap from fuel filler neck. –  Take off engine cover panel -arrows-.   WARNING The fuel system is pressurised. Before opening the system place a clean cloth around the connection. Then release pressure by carefully loosening the connection.

–  Disconnect fuel supply line -arrow-.

–  Connect K-Jetronic pressure tester -V.A.G 1318- to fuel supply pipe with adapters -V.A.G 1318/11- and -V.A.G 1318/12-. –  Fit auxiliary hose -arrow- onto K-Jetronic pressure tester -V.A.G 1318- and hold it into a container. –  Open cut-off valve on K-Jetronic pressure tester -V.A.G 1318-. Lever must point in direction of flow. –  Bleed fuel system by pressing remote control switch briefly.

–  Close cut-off valve on K-Jetronic pressure tester -V.A.G 1318-. Lever is at right angle to direction of flow -arrow-. –  Press and hold remote control switch until K-Jetronic pressure tester -V.A.G 1318- shows no further increase in pressure. 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 pipe 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:

–  Switch off ignition.   Note Before removing the pressure tester, release the fuel pressure by opening the cut-off valve. When doing this, hold auxiliary hose in container to catch fuel. –  Re-connect fuel supply line (make sure that all parts are clean). Tightening torque

Component	Nm
Fuel line to fuel rail	22