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  Auxiliary measuring set -V.A.G 1594C-

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 t  Protective gloves Checking fuel pressure 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. l  Ignition off. Checking fuel pressure –  Remove rear seat bench → Rep. gr.72.

–  Unbolt cover for flange -arrows-.

–  Unplug electrical connector -1- at flange.   Note Disregard -item 2-. –  Connect remote control -V.A.G 1348/3A- for V.A.G 1348 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. –  Connect contact -5- to the body (earth) using a test lead from auxiliary measuring set -V.A.G 1594C-. –  –  Connect remote control -V.A.G 1348/3A- for V.A.G 1348 to item -A- of junction box in plenum chamber (battery positive). For safety reasons an in-line fuse (10 A) must be connected into the lead. –  Move switch of remote control -V.A.G 1348/3A- for V.A.G 1348 to front of engine compartment.

–  Remove seal -arrow-. –  Unclip plenum chamber cover -2- and remove.   Note Disregard -items 1 and 3-.

–  Release retainer -arrow A- and open cover -arrow B-.

–  Connect remote control -V.A.G 1348/3A- for V.A.G 1348 to item -A- of junction box in plenum chamber (battery positive). For safety reasons an in-line fuse (10 A) must be connected into the lead. –  Remove filler cap from fuel filler neck. –  Pull off engine cover panel (front).

–  Disconnect fuel supply pipe -arrow- at high-pressure pump.   WARNING Risk of injury - fuel system operates under high pressure. To reduce the pressure in the fuel system, wrap a clean cloth around the connection and carefully loosen the connection.

–  Connect K-Jetronic pressure tester -V.A.G 1318- to fuel supply pipe with an adapter. –  Fit test hose -arrow- onto pressure tester and hold end of hose into a container to catch escaping fuel. –  Open cut-off valve on pressure tester. l  Lever points in direction of flow. –  Bleed fuel system by pressing remote control switch briefly.

–  Close cut-off valve on pressure gauge. l  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. 5.5 bar (4.5 ... 6.5 bar) If specification is not obtained: –  Check delivery rate of fuel pump → Rep. gr.20. Checking residual pressure –  Check for leaks and check residual pressure by watching drop in pressure on pressure tester. 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  Check delivery rate of fuel pump → Rep. gr.20. t  Renew fuel filter with integrated fuel pressure regulator → Rep. gr.20. t  Non-return valve of fuel pump is defective → Rep. gr.20. Assembly is carried out in the reverse order; note the following: –  Switch off ignition.   Note Before removing pressure gauge, release fuel pressure by opening cut-off valve. Hold a container under the connection.

–  Re-connect fuel supply pipe -arrow- to high-pressure pump.   Note Check fuel system for leaks.