Checking the fuel delivery rate — VW

Checking the fuel delivery rate
Voltage supply OK.
Fuel pressure regulator and holding pressure OK, checking
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Fuel filter OK.
Remove cap from fuel filler neck.
Open cover of relay and fuse holder of engine compartment E-box.
Pull fuse SB33 out of socket F33 of fuse holder.
Connect
remote control
V.A.G 1348/3 A
with
adapter cable
V.A.G 1348/3-3
to right terminal of fuse socket F33.
Tape off 2nd connector contact of the
adapter cable
V.A.G 1348/3-3
with insulating tape
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to prevent short circuits.
Connect crocodile clip to vehicle battery (+).
Note
Delivery rate of fuel pump must be measured at 4 bar. Therefore, test fuel pressure before measuring fuel delivery rate
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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 joint. Then release the pressure by carefully pulling the hose off the connection.
Pull the return line
1
off the fuel pressure regulator.
Note
Press in securing ring to release fuel line.
Connect
adapter
VAS 6550/1
to fuel pressure regulator and hold the end of the adapter in a measuring vessel.
Operate remote control
V.A.G 1348/3A
for approx. 5 seconds to fill fuel filter.
Drain measuring container.
The delivery rate of the fuel pump depends on the voltage. Therefore connect the multimeter to the battery.
Operate remote control for 30 seconds and measure the battery voltage.
Compare delivered quantity of fuel with specification.
*) Minimum delivery rate cm³/30 s
**) 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. Because the voltage at the pump is approx. 2 volts less than the battery voltage, this will result in a minimum delivery rate of 580 cm³/30 s.
If minimum delivery rate is not attained:
Check supply line to filter for possible restrictions (kinks) or blockages.
If fuel line is OK
Check fuel delivery rate before fuel filter. Proceed as follows to do this:
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 joint. Then release the pressure by carefully pulling the hose off the connection.
Pull fuel supply line
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off fuel filter.
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 the shut-off tap
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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.
Operate the remote control again for 30 seconds. Compare the fuel delivery rate with the first measurement.
If the minimum delivery rate is now achieved:
Renew fuel filter.
If the minimum delivery rate is again not achieved
Remove fuel delivery unit and check filter strainer for contamination.
Only if still no fault has been detected:
Renew fuel delivery unit
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Reconnect all disconnected fuel lines.
Bleeding fuel system
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