Volkswagen Workshop Service and Repair Manuals

Checking delivery rate –  Remove seat bench → General body repairs, interior; Rep. Gr.72.

–  Remove cover -1- with fuel pump control unit -J538--2- from fuel delivery unit. –  Pull 5-pin connector off fuel delivery unit flange.

–  Connect remote control -V.A.G 1348/3A- to contact -1 (+)- of fuel pump and contact -1 (+)- of connector using adapter cables. –  Connect contacts -6 (-)- of connector and -5 (-)- of fuel pump using an adapter cable from auxiliary measuring set -V.A.G 1594/C-. –  Remove filler cap from fuel tank filler neck.

–  Pull off supply line -2- and catch escaping fuel with a cloth.   Note Press in safety ring to release fuel lines.

–  Connect pressure tester -V.A.G 1318- with connector -V.A.G 1318/23- and adapter set -V.A.G 1318/17-. –  Push hose adapter -V.A.G 1318/16- onto adapter -V.A.G 1318/11- of pressure tester and hold it in measuring container.   WARNING Danger of spray when shut-off tap is opened. Wear protective glasses and clothing to avoid injuries and skin contact. Hold container over free connection of pressure tester. –  Close cut-off tap of pressure tester. The lever then points in direction of flow -A-. –  Operate remote control -V.A.G 1348/3A-. Then slowly close cut-off tap until a pressure of 4 bar is displayed on pressure gauge. From this point on do not move position of cut-off tap. –  Empty measuring container. –  The quantity delivered by the fuel pump depends on the battery voltage. Therefore connect multimeter -V.A.G 1715- with adapter cables from auxiliary measuring set -V.A.G 1594/C- to vehicle battery. –  Operate remote control for 30 seconds while measuring battery voltage.

–  Compare quantity of fuel delivered with specification. *) Minimum delivery rate cm3/30 seconds. **) Voltage at fuel pump with engine not running and pump running (approx. 2 volts less than battery voltage). Example During the test a voltage of 12.5 volts is measured at the battery. As the voltage at the pump is approx. 2 volts less than the battery voltage, this will equate to a minimum delivery rate of approx. 580cm3/30 seconds. If the minimum delivery rate is not attained. –  Check fuel lines for possible restrictions (kinks) or blockages. If no fault is found.   WARNING The fuel supply line is under pressure! Wear protective glasses and clothing 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 supply hose -1- off fuel filter inlet. –  Connect pressure tester -V.A.G 1318- with adapter set -V.A.G 1318/17- to hose. –  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 for dirt in filter strainer. Only if still no fault has been detected. –  Renew fuel delivery unit. If delivery rate has been attained, but nevertheless you suspect a fuel supply system fault (e.g. intermittent failure of fuel supply system): –  Measure current consumption of fuel pump → Chapter.