Volkswagen Workshop Service and Repair Manuals

Test procedure –  Remove fuse No. 28 (fuel pump) from fuse holder.   WARNING Fuel supply lines are under pressure! Wear eye protection and gloves to avoid injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Pull off supply line -1- and catch escaping fuel with a cloth.

–  Connect pressure tester -V.A.G 1318- to fuel supply line and hose to fuel rail using adapter -V.A.G 1318/9- and adapter set -V.A.G 1318/17-. –  Open shut-off valve of pressure tester -V.A.G 1318-. The handle points in direction of flow. –  Refit fuse 28 (fuel pump) in fuse holder. –  Start engine and run at idling speed. –  Measure fuel pressure. Specification: approx. 2.5 bar.

–  Pull vacuum hose off fuel pressure regulator -arrow-. The fuel pressure must increase to approx. 3.0 bar. –  Switch off ignition. If the specification is not attained: –  Check delivery rate of fuel pump → Chapter. If specification is attained: –  Now check for leaks and holding pressure. Do this by observing pressure drop on gauge. After 10 minutes, there must be a residual pressure of at least 2.0 bar. If the holding pressure drops below 2 bar: –  Start engine and run at idling speed.

–  Switch ignition off after the pressure has built up. At the same time, close shut-off tap of pressure tester -V.A.G 1318- (lever at right angles to direction of flow -arrow-). –  Watch pressure drop on pressure gauge. If the pressure does not drop: –  Check fuel pump non-return valve → Chapter. If the pressure drops again:

–  Open pressure gauge -V.A.G 1318- shut-off tap (handle in direction of flow). –  Start engine and run at idling speed.

–  Switch ignition off after the pressure has built up. At the same time pinch together/seal return hose -2- (blue marking). If the pressure does not drop: –  Renew fuel pressure regulator → Item. If the pressure drops again: –  Check line connections, O-rings on fuel rail and injectors for leaks. –  Check pressure tester -V.A.G 1318- for leaks.   Note Before removing pressure tester -V.A.G 1318-, place a cloth around the connections to be undone.