Suction Jet Pump, Checking
The fuel tank in a vehicle with all-wheel drive is divided into a left and right chamber. To move the volume of fuel from the left fuel tank chamber -3- to the right baffle housing of the fuel delivery unit -2-, a suction jet pump -1- is utilized.
Function of suction jet pump:
Function of the suction jet pump is based on a simple physical principle: A suction jet from the electrical fuel pump is compressed by a nozzle in the suction jet pump and is thereby accelerated. This acceleration causes the surrounding fuel to be drawn in and be forced to the baffle housing of the fuel delivery unit.
Malfunctions of defective suction jet pump:
Tow-in due to faulty suction jet pump.
- If suction jet pump is defective, the vehicle can stop running due to lack of fuel, though the fuel tank is up to 1 /4 filled.
If the suction jet pump does not work, up to 15 liters (4 gallons) of fuel (up to 1 /4 of a tank) can be remaining in the left chamber of the fuel tank.
This fuel cannot not be extracted from the fuel delivery unit.
If the vehicle does start due to lack of fuel even though the fuel tank is 1 /4 full, proceed as follows:
-- Check the Transfer Fuel Pump -G6-, refer to FUEL PUMP, CHECKING .
If the fuel pump is OK but fuel is still not being delivered:
-- Add approximately 5 liters (1 gallon) of fuel.
-- Start the engine.
If the engine starts now:
-- Replace the suction jet pump, refer to SUCTION JET PUMP .