Skoda Workshop Service and Repair Manuals

Checking fuel flow rate with pressure gauge -V.A.G 1318-   Note t  Safety precautions when working on the fuel supply system → Chapter. t  Rules of cleanliness when working on the fuel supply system → Chapter. –  Switch off the ignition and all electrical components and take out the ignition key. –  Removing rear seat bench → Body Work; Rep. Gr.72.

–  Unclip the cover -4- with the fuel pump control unit -J538--1-.

–  First of all check the plug -1- for correct fit. To do so, pull on the plug without pressing the catch. If the plug connection was not correctly positioned, this could cause a fault. –  Now unplug the plug -1-. –  Check the contacts at the plug and at the fuel delivery unit for damage.

–  Connect the adapter for measuring method/DSO (5-pin) -VAS 5565- to the plug connection and to the fuel delivery unit. –  Connect remote control -V.A.G 1348/3A- to adapter -VAS 5565- and to battery positive (+).   Note This step is only intended to ensure that the fuel delivery unit runs when the engine is switched off.

–  Disconnect the feed line -2- (press in the securing ring to the top) and catch the fuel which flows out with a cleaning cloth.

–  Connect the pressure gauge -V.A.G 1318- with the double connection piece -V.A.G 1318/23 - and the adapter -V.A.G 1318/17A- to the fuel feed line. –  Fit hose adapter -V.A.G 1318/16 - onto the adapter -V.A.G 1318/11- of the pressure measuring device and hold in a measuring vessel. –  Close the shutoff cock of the pressure measuring device. The lever then points in the position -B-.   WARNING Danger of liquid spraying out when opening the shut-off valve. Wear safety goggles and safety clothing, in order to avoid injuries and skin contact with fuel. Hold the container in front of the free connection to the pressure gauge. –  Open shut-off cock of the pressure gauge. The lever then points in the direction of flow -A-. –  Activate remote control -V.A.G 1348/3A -. While doing so, slowly close the shut-off cock until the pressure gauge displays 0.4 MPa (4 bar) overpressure. Now do not make any further changes to the position of the shut-off cock. –  Empty measuring glass.

–  The fuel flow rate of the fuel delivery unit is dependent on the battery voltage. For this reason, additionally connect the multimeter -V.A.G 1715- to the outgoing circuits -1 and 5- of the adapter for measuring method/DSO (5-pin) -VAS 5565-. –  Activate remote control for 30 seconds while measuring the battery voltage.

–  Compare the fuel rate with the specified value. *) minimum flow rate 1 cm3/30 s **) Voltage at the fuel pump when engine not running and delivery unit operating. Read out examples: During the test a voltage of 10.5 V was measured. Thus a minimum flow rate of 580 cm3/30 s is obtained. If the minimum flow rate is not reached: –  Check the fuel lines for possible restrictions (kinks) or blocking. If no fault is found: –  Take cap off fuel filler neck and repeat the test. If the fuel flow rate is now reached: –  Check the ventilation of the fuel tank. If the minimum flow rate is again not reached:

–  Disconnect the feed hose -1- from the fuel filter inlet. –  Connect pressure gauge -V.A.G 1318- with the adapter set -V.A.G 1318/17A- to the hose. –  Repeat fuel flow rate test. If the minimum flow rate is now reached: –  Replace fuel filter. If the minimum flow rate is again not reached: –  Remove fuel delivery unit and inspect filter strainer for soiling. If you have still not found any fault up to this stage: –  Replace fuel delivery unit → Chapter. If the required fuel flow rate has been achieved, but a fault is still suspected in the fuel supply system (e.g. intermittent breakdown of the fuel supply): –  Check power consumption of the fuel delivery unit → Chapter.