Fuel supply system - Petrol engines

Removing and installing suction-jet pump

~1min read
On vehicles with four-wheel drive the fuel tank is divided into a left and a right chamber. A suction-jet pump -2- is used for delivering fuel from the left fuel tank chamber to the baffle housing of the fuel delivery unit -1- on the right.

Function of suction-jet pump

The suction-jet pump operates according to the principle of fluid entrainment: the stream of fuel from the electrical fuel pump is passed through a nozzle in the suction-jet pump, and is thus accelerated. The accelerated stream of fuel draws off the surrounding fuel and delivers it to the baffle housing of the fuel delivery unit.

Faults caused by defective suction-jet pump

Note

Risk of breakdown due to defective suction-jet pump.

If the suction-jet pump is defective, the engine can stop due to fuel starvation when the tank is still 1/4 full. If the suction-jet pump does not work, approx. 15 litres of fuel (1/4 of tank capacity) remain in the left chamber of the fuel tank and cannot be extracted by the fuel delivery unit. If the engine stops due to fuel starvation with the tank filled up to about 1/4, proceed as follows:
  • Check fuel pump with → Vehicle diagnostic tester.

If fuel pump is OK, but no fuel is delivered:

  • Refill fuel tank with approx. 5 litres of fuel.
  • Start engine.

If engine starts OK now:

  • The suction-jet pump cannot be renewed individually. Renew fuel tank → Chapter.
Removing and installing suction-jet pump

Test yourself

A quick Volkswagen Golf quiz: every answer comes with an explanation and a link to the manual page.