Volkswagen Workshop Service and Repair Manuals

Checking fuel delivery rate (engine codes CBTA, CBUA, BGP, BGQ) l  Voltage supply OK. l  Fuel pressure regulator and holding pressure OK, testing → Rep. gr.24 l  Fuel filter OK. –  Remove bench seat → Rep. gr.72.

–  Remove cover from fuel delivery unit.

–  First check that the connector -arrow- is fitted securely by pulling the connector without pressing the catch. The connector can cause a fault if it has not been fitted correctly. –  Now pull off connector. –  Check the contacts on the connector and on the 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 test instrument adapter/DSO (5-pin) -VAS 5565- and to battery positive (+).   Note t  This step serves only to have the fuel pump running when the engine is stopped. t  Delivery rate of fuel pump must be measured at 4 bar. Therefore, test fuel pressure before measuring fuel delivery rate → Rep. gr.24.   WARNING Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid possible injury and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Disconnect return line -1- from fuel pressure regulator. Separate push-on couplings → Chapter. –  Connect adapter set -VAS 6550/1- to fuel pressure regulator and hold end of adapter in measuring container. –  Operate remote control -V.A.G 1348/3A- about 5 seconds to fill fuel filter. –  Empty measuring container.

–  The quantity of fuel delivered by the fuel pump is dependant on the system voltage, therefore, also connect multimeter -V.A.G 1526D- to contacts -1 and 5- of 5-pin test instrument/DSO adapter -VAS 5565-. –  Operate remote control for 30 seconds while measuring battery voltage.

–  Compare quantity of fuel delivered with specification. *) Minimum delivery rate cm³/30 s **) Voltage at fuel pump with engine not running and pump running. Example: During the test a voltage of 10.5 volts is measured. This equates to a minimum delivery rate of approx. 580cm³/30 s. If the specification is not attained: –  Check supply line to filter for possible restrictions (kinks) or blockages. If fuel line is OK –  Remove cap from fuel filler neck and repeat check. If fuel delivery rate is now reached, check fuel tank breather. If the specifications are still not attained: –  Check fuel filter (proceed as follows):   WARNING Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid possible injury and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

–  Pull fuel supply line -arrow- off fuel filter. Separate push-on couplings → Chapter.

–  Connect pressure tester -VAS 6550- to fuel supply line with adapter -VAS 6550/1-. Hold adapter -VAS 6550/2- in a measuring container. –  Make sure that drain tap is closed and cut-off taps are open. –  Operate remote control -V.A.G 1348/3A-. Then slowly close shut-off tap -A- until a pressure of 4 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. If the minimum delivery rate is now attained: –  Renew fuel filter. If the minimum delivery rate is again not attained –  Remove fuel delivery unit and check filter strainer for soiling. Only if still no fault has been detected: –  Renew fuel delivery unit → Chapter. –  Reconnect all disconnected fuel lines. –  Bleed fuel system. If fuel delivery rate has been attained, but nevertheless you suspect a fuel supply system fault (e.g. intermittent failure of fuel supply system): –  Measure current draw of fuel pump → Chapter.