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 set -V.A.G 1318/17A-

t	Connector -V.A.G 1318/23-

t	Remote control -V.A.G 1348/3A- for V.A.G 1348 with adapter cable -V.A.G 1348/3-3-

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

t	Fuel-resistant measuring container

Test conditions l  Battery voltage at least 12.5 Volt. l  Fuel filter OK. l  Fuel tank at least 1/4 full. l  Fuel pump control unit -J538- OK; checking in Guided Fault Finding → Vehicle diagnostic tester.

Preparations l  Ignition off. –  Remove rear seat bench → Rep. gr.72. –  Unscrew cover for flange -arrows-.

–  Unplug electrical connector -1- on flange.   Note Disregard -item 2-.

–  Lift cover -1- by its handle -arrow-.

–  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 vehicle body (earth) using a test lead from auxiliary measuring set -V.A.G 1594C-. –  Move switch of remote control -V.A.G 1348/3A- for V.A.G 1348 to front of engine compartment.

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

–  Connect crocodile clip to jump start socket -U6--item A- in terminal 30 wiring junction 2 -TV22- located in plenum chamber. –  Remove filler cap from fuel filler neck.

–  Pull off engine cover panel → Chapter.   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. –  Push down protective sleeve -1- and disconnect fuel supply line. –  First press hose connector -2- downwards -arrow A-, then press release tabs -arrow B-. –  Pull off hose connector, keeping release tabs depressed.

–  Screw connector -V.A.G 1318/23- and adapter -V.A.G 1318/17-1A- onto K-Jetronic pressure tester -V.A.G 1318-. –  Fit -V.A.G 1318/17-1A- onto disconnected fuel line. –  Connect adapter -V.A.G 1318/11- to -V.A.G 1318-. –  Attach test hose -arrow- and hold end of hose in measuring container. –  Open cut-off valve on pressure tester. l  Lever points in direction of flow. –  Bleed fuel system by pressing remote control briefly.

Checking fuel pressure –  Close cut-off valve on pressure tester. l  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. 5.5 bar (4.5 ... 8.0 bar) –  If specification is not attained, check delivery rate of fuel pump → 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 3.0 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  Check fuel filter with integral fuel pressure regulator → Rep. gr.20. t  If fuel filter is OK, renew fuel pump → Rep. gr.20. Installation 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 end of test hose into measuring container -arrow-. –  Re-attach fuel supply line (make sure that all parts are clean and that there are no leaks).