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VW Golf Mk1 Service and Repair Manuals

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Checking fuel pump non-return valve > < Checking function and voltage supply

Checking fuel delivery rate for Golf Mk1 4 Cylinder Fuel injection Engine Mechanics

4 Cylinder Fuel injection Engine Mechanics (1.6L & 1.4L)
Removing and installing parts of fuel supply system
Checking delivery rate

Test conditions

  • ● Battery voltage at least 11.5 V.
  • ● Remote control V.A.G 1348/3A connected.
Attention!
Fuel supply lines are under pressure! Before removing from hose connection wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.

Test sequence
 
U20-0074
  • ‒ Remove filler cap from fuel tank filler neck.
  • ‒ → Pull the fuel supply pipe -1- off fuel rail.
  • ‒ Connect pressure gauge V.A.G 1318 with adapter 1318/10 to the fuel supply pipe -1-.
  • ‒ Push the hose V.A.G 1318/1 onto the adapter V.A.G 1318/11 on the pressure gauge and hold hose in a measuring container.
  • ‒ Open the pressure gauge cut-off tap. The lever then points in the throughflow direction -A-.
  • ‒ Operate remote control V.A.G 1348/3A. Whilst doing this slowly close the cut-off tap, until gauge shows 3 bar.

From now on do not alter the position of the cut-off tap.

  • ‒ Empty the measuring container.
  • ‒ Connect multimeter to vehicle battery to measure voltage using auxiliary cables from V.A.G 1594.
  • ‒ Operate remote control for 30 seconds.
 
U20-0075
  • ‒ → Graph for comparing the quantity of fuel delivered with the specification.
  • *) Minimum delivery cm3/30 seconds.
    **) Voltage at fuel pump with engine stationary 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 then this will equate to a minimum delivery of 500 cm3/30 s.

If the minimum delivery rate is not attained:

  • ‒ Check the fuel pipes for possible restrictions (kinks) or blockage.
 
U20-0076
  • ‒ → Pull the supply hose -1- off inlet to the fuel filter.
  • ‒ Connect pressure gauge V.A.G 1318 with adapter 1318/10 to the fuel supply pipe -1-.
  • ‒ Repeat delivery rate check.

If the minimum delivery rate is now attained:

  • ‒ Replace fuel filter.

If the minimum delivery rate is again now attained:

  • ‒ Replace fuel pump.

If the delivery rate has been attained but nevertheless you suspect a fuel supply system fault (e.g intermittent failure of fuel supply system).

  • ‒ Check the current draw of the fuel pump as follows:
  • ‒ Reconnect all disconnected fuel pipes.
 
U20-0077
  • ‒ → Connect the multimeter V.A.G 1715 using the current clamp to the positive wire of fuel pump in wiring loom.
  • ‒ Start the engine and run at idle speed.
  • ‒ Measure the current draw of the fuel pump.
    Specification: max. 8 amps.

If the current draw is exceeded:

  • ‒ Replace the fuel pump.

Checking fuel pump non-return valve > < Checking function and voltage supply