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 set -V.A.G 1318/10-12-

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  Fuel filter OK l  Fuel tank at least 1/4 full. l  Fuel pump control unit -J538- OK; checking → Rep. Gr.20. l  Ignition off. Checking fuel pressure Saloon models with front-wheel drive: –  Detach trim in luggage compartment. –  If necessary, fold forward right backrest of rear seat bench. Avant models with front-wheel drive: –  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 models with front-wheel drive: –  If necessary, fold forward right backrest of rear seat bench. –  Take out luggage compartment floor trim. –  Unscrew cover for flange -arrows-.

–  Carefully release electrical connector from flange -arrow- and unplug.

Vehicles with four-wheel drive: –  Remove rear seat bench → Rep. Gr.72. –  Unscrew cover for flange (right-side) -arrows-.

–  Carefully release electrical connector from flange -arrow- and unplug.

All models: –  Connect remote control for V.A.G 1348 -V.A.G 1348/3A- to contact -1- using adapter cable -V.A.G 1348/3-3- and test lead from auxiliary measuring set -V.A.G 1594C-. –  Tape off 2nd connector contact of adapter cable -V.A.G 1348/3-3- with insulating tape -arrow- to prevent short circuits. –  Move switch of remote control -V.A.G 1348/3A- for V.A.G 1348 to front of engine compartment. –  Connect contact -4- to body earth via an improvised auxiliary lead. –  Connect crocodile clamp to battery “+”.

–  Pull off engine cover (rear) -arrows-.   WARNING t  The fuel system operates under high pressure. The pressure in the high-pressure part of the injection system must be reduced to a residual pressure prior to opening the system → Chapter. t  A clean cloth must then be wrapped around the connection and the residual pressure dissipated by carefully loosening the connection.

–  Disconnect fuel line -arrow-.

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

–  Close cut-off tap on pressure gauge. Lever is at right angle to direction of flow -arrow-. –  Press switch on remote control until pressure gauge shows no further increase in pressure. l  Specification: approx. 6 bar If specification is not obtained: –  Check fuel pump delivery rate → Rep. Gr.20. Checking residual pressure –  Check leak-tightness and residual pressure by watching the drop in pressure on the pressure gauge. l  After 10 minutes pressure should still be at least 3.75 bar. If the residual pressure drops below 3.75 bar: t  Check union between pressure gauge and fuel line for leaks. t  Test pressure gauge for leaks. t  Check fuel lines and their connections for leaks. t  Renew fuel filter with integral fuel pressure regulator → Rep. Gr.20. t  Renew fuel pump → Rep. Gr.20. Assembly is carried out in the reverse order; note the following:   Note Before removing the pressure tester, release the fuel pressure by opening the cut-off valve. Hold a container under the connection. Tightening torque

Component	Nm
Fuel line to fuel rail	28