Petrol engine 2.5-I-V6-TDI
The fuel pump is located in the fuel tank.
Security note. When working on the fuel system, do not use open flames or tools that may generate sparks. Make sure there is a charged fire extinguisher in the immediate vicinity of the workplace.
Fuel vapors are poisonous, so work on the fuel system must be carried out in a well-ventilated area.
The fuel system is under pressure. When disconnecting system components, fuel can splatter, so use goggles to protect your eyes from fuel getting into them.
Check the battery voltage, which should not be. less than 11.5 V.
Checking the voltage supply
Check the No. 28 fuse for the fuel pump. If the fuse is blown, replace it.
Turn on the starter for a short time, while you should hear a short (about 1 s) fuel pump operation. You can hear the noise of the fuel pump near the fuel tank.
If the fuel pump is not working, check the fuel pump control circuits (see above).
Turn on switch 1 (pic. 4A.14). If the pump runs, check the fuel pump relay.
Pic. 4A.14. Devices necessary for checking the power supply circuit of the fuel pump
1 - switch,
2 - clamp type «Crocodile» (with cable for battery connection),
3 - movable fuse for 8 As with wires,
4 - single-pin electrical connector (connects instead of the fuel pump fuse),
5 - two-core wire with a cross section of 1.5 mm2 and a length of 5 m.
If the fuel pump does not work, do the following.
Unscrew and remove the fuel gauge/fuel pump access cover. Disconnect the fuel level sender/fuel pump connector (see fig. 1).
Connect an LED tester or a voltmeter to the external contacts of the connector disconnected from the fuel pump (see fig. 4A.15).
Turn on switch 1 (pic. 4A.14). Voltmeter should show battery voltage (12 V). Otherwise, check the condition of the wires supplying voltage to the fuel pump.
If the voltmeter shows battery voltage, remove and check the fuel pump.
Check the connection of the electrical connector between the flange and the fuel pump. Also check the condition and resistance of the wires going to the fuel pump. Use guide lines if necessary.
If the test fails, then the fuel pump is faulty and needs to be replaced.
Install the fuel pump and connect the electrical connectors to it.
Checking the performance of the fuel pump
Remove the cap from the fuel filler neck.
Remove the engine cover and unscrew the spark plugs.
Security note. The fuel system is under pressure. Depressurize the fuel system before disconnecting the fuel lines. To do this, cover the connection point with a rag and, being careful, disconnect. When disconnecting system components, fuel can splatter, so use goggles to protect your eyes from fuel getting into them.
Disconnect the fuel return line from the fuel line (see fig. 4A.16).
Instead of a fuel return line, connect an additional hose to the fuel line, lower the free end of which into a measuring vessel (see fig. 4A.16).
Connect a voltmeter to the battery terminals.
Turn on switch 1 for 15 seconds, while using a voltmeter, determine the voltage of the battery (pic. 4A.14).
According to the graph shown in Figure 4A.17, determine the performance of the fuel pump, while taking into account that when the starter is running, the voltage decreases by 2 V.
Compare the volume of fuel in the measuring vessel with the data obtained from the graph.
Example: During the performance test, the battery voltage was 12.5 V. Since the voltage at the fuel pump is about 2 V less than the battery, the voltage at the fuel pump is 10.5 V (12,5-2 =10,5). This voltage corresponds to a fuel pump output of approximately 275 cm3 /15s.
If the voltage supplied to the fuel pump is normal, and the performance of the fuel pump is low, check that the fuel lines are not pinched or dirty inside.
Also check if the fuel filter is dirty. Check the performance of the fuel pump with a new fuel filter.
If the performance is still below normal, remove the fuel pump and check the condition of the strainer at the pump inlet, and clean it if necessary.
If everything is in order, check the fuel pump check valve.
If the performance is still below normal, check the current drawn by the fuel pump, which should be around 8A. Otherwise, the fuel pump must be replaced.
Disconnect the auxiliary hose from the fuel line and reconnect the fuel return line.
Disconnect the fuel pump control test circuits and reinstall the #28 fuse.
Install the cover over the fuel pump mounting flange and screw it on.
Reinstall the filler cap.
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