Checking vacuum between high-pressure fuel pump (venturi nozzle) and injectors

Do not perform this test until the vacuum at the high-pressure pump (venturi nozzle) has been checked

⇒ Fuel supply system; Rep. gr. 20

• Make return line connection accessible. Release catch -1- to do this.
• Pull fuel return line connection in direction of arrow off injector.
• Ask a second mechanic for assistance.

• Close shut-off tap of pressure tester - VAS 6551- -A- + -B- and open -C-.
• Connect connection -C- on pressure tester - VAS 6551- with hose adapter - VAS 6551/3- to fuel return line.

• Connect hose adapter - VAS 6551/4- to fuel return line connection on injector and hold free end into a ≤ 3 litre measuring container -3-.
• Switch on pressure tester - VAS 6551- by pressing On/Off button and calibrate it.
• Switch on ignition.
• Start engine.

• Take pressure reading on pressure tester - VAS 6551-.

Specification: min. – 0.10 bar

If the specified value is not reached, first check the delivery pressure in the fuel return system ⇒ Fuel supply system; Rep. gr. 20.

If the specified value is still not reached: Replace fuel return line. ⇒ Item 2 (page 213)

• Drain measuring container.