Mechanical fuel pump — checking, adjustment, removal and installation (BMW 3 Series E21)

Cleaning

Remove the cover, O-ring and pump strainer.

Thoroughly clean the pump surface from dust and dirt and remove foreign particles from the filter.

Install the filter, sealing ring and replace the pump cover, tightening the mounting bolt.

Checking the fuel pump discharge pressure and the condition of the carburetor needle valve

Connect the pressure gauge hoses to the carburetor and fuel pump, and the hose going to the carburetor should be equipped with a tap.

Run the engine at idle speed and read the pressure gauge. If the pressure is below 0.05 kg/cm², replace the fuel pump.

Stop the engine and close the tap; the fuel pressure in the system should be 0.29-0.30 kg/cm². If the pressure drops, replace the carburetor needle valve.

Removal and installation the fuel pump

Remove the pump after disconnecting the fuel hoses from it.

Check the condition of the heat-insulating gasket and seals and replace them if damaged.

Install the pump and connect the fuel hoses to it.

Adjusting the throttle actuator

Warm up the engine.

Adjust the throttle actuator with the two adjusting nuts 1 on the intermediate support so that the actuator operates without jamming.



When the accelerator pedal is fully depressed, the throttle valve opening limiter of the 1st chamber should rest against the lower stop.