Volkswagen Workshop Service and Repair Manuals

Checking fuel delivery rate   Note If driving characteristic problems occur when the fuel tank is approx. 1/4 filled, the fuel delivery rates check should be carried out with fuel tank filled up to 1/4 or less of its capacity. –  Observe safety precautions → Chapter. –  Observe rules for cleanliness → Chapter. l  Battery charger connected. l  Filling level in fuel tank above reserve. l  Voltage supply OK → Chapter. l  Fuel pressure OK → Chapter. –  Remove bench seat → General body repairs, interior; Rep. gr.72.

–  Unclip cover -1- at retaining tabs -arrows-, using removal wedge -3409-.

–  Check that connector -1- is fitted securely by pulling connector without pressing catch. If connector was not inserted correctly, repeat functional check of fuel pump. –  Release and pull off connector -1-. –  Check contacts on plug and on fuel delivery unit for damage.

–  Connect test instrument adapter/DSO (5-pin) -VAS 5565- to connector and fuel delivery unit. –  Connect remote control -V.A.G 1348/3A- to adapter -VAS 5565- and to battery positive terminal in engine compartment.   Note This step serves only to have the fuel pump running when the engine is stopped.   WARNING Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid eye injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect supply line -1- (black) and catch escaping fuel with a cloth. Separate push-on couplings → Chapter.

–  Connect pressure tester -VAS 6550- to fuel supply line with adapter -VAS 6550/2-. Hold adapter -VAS 6550/1- in a measuring container.

–  Make sure that drain tap -C- is closed and cut-off taps -A- and -B- are open.   WARNING Danger of spraying! Wear eye protection and protective clothing to avoid eye injuries and skin contact. Hold container before the free connection of pressure tester -VAS 6550-. –  Operate remote control -V.A.G 1348/3A-. Then slowly close shut-off tap -arrow- until a pressure of 3 bar is displayed on pressure gauge. From this point on do not move position of shut-off tap. –  Drain measuring container.

–  The quantity of fuel delivered by the fuel pump is dependant on the battery voltage. The multimeter -V.A.G 1715- must therefore be connected to contacts -1- and -5- of 5-pin test instrument/DSO adapter -VAS 5565- as well. –  Operate remote control for 60 seconds, whilst measuring voltage at fuel pump. –  Compare delivered quantity of fuel with specification. Minimum delivery cm3/60 seconds Voltage at fuel pump with engine not running and pump running is 12 V. Specification: approx. 1050 cm3/60 s. If the specification is not attained: –  Open tank flap.

–  Remove cap -arrow- from fuel filler neck. –  Repeat delivery rate check. –  If fuel delivery rate is now reached, check fuel tank breather → Chapter. If the specifications are still not attained: Proceed as follows to check fuel delivery rate at separating point on underbody:   WARNING Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid eye injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect fuel supply line -2-. Separate push-on couplings → Chapter.

–  Connect pressure tester -VAS 6550- with adapter -VAS 6550/1- and -VAS 6550/2- to push-on coupling of fuel supply line -1-. t  VAS 6550/1 between fuel line leading to engine compartment and shut-off tap -B- t  VAS 6550/2 between measuring container (capacity 3 litres) and shut-off tap -A- If the minimum delivery rate is now attained: –  Check fuel line between separating point on underbody and separating point in engine compartment for possible restrictions (kinks) or blockages. If the specifications are still not attained: Proceed as follows to check fuel delivery rate at fuel delivery unit:   WARNING Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid eye injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect fuel supply line -2-. Separate push-on couplings → Chapter.

–  Connect pressure tester -VAS 6550- with adapter -VAS 6550/2- to fuel delivery unit. Hold adapter -VAS 6550/1- in a measuring container. t  VAS 6550/1 between measuring container (capacity 3 litres) and shut-off tap -B- t  VAS 6550/2 between fuel delivery unit and shut-off tap -A-

–  Make sure that drain tap -C- is closed and cut-off taps -A- and -B- are open.   WARNING Danger of spraying! Wear eye protection and protective clothing to avoid eye injuries and skin contact. Hold container before the free connection of pressure tester -VAS 6550-. –  Operate remote control -V.A.G 1348/3A-. Then slowly close shut-off tap -arrow- until a pressure of 3 bar is displayed on pressure gauge. From this point on do not move position of shut-off tap. –  Drain measuring container. –  Repeat delivery rate check at fuel delivery unit. If the minimum delivery rate is now attained: –  Check fuel lines for possible restrictions (kinks) or blockages. If the minimum delivery rate is again not attained –  Remove fuel delivery unit → Chapter. –  Check filter strainer for soiling.

–  Check that all hose connections -arrows- are connected. Only if no fault has yet been detected: –  Renew fuel delivery unit → Chapter If fuel delivery rate has been attained, but nevertheless you suspect a fuel supply system fault: –  Check current consumption of fuel pump → Chapter.