Adjusting the accelerator pump:
1 - fuel injection start adjusting nut; 2 - fuel supply adjustment screw
1. Remove the air filter.
2. Press the throttle control lever several times; at the same time, a stream of fuel should emerge from the two nozzles of the accelerator pump.
3. If this does not happen, clean the sprayers, wash them with gasoline and blow them with compressed air, and also check the condition of the diaphragm, which should be intact, without damage (when assembling the accelerator pump, direct the small diameter conical helical spring towards the diaphragm).
4. Move the throttle actuator back until the idle mixture quantity adjusting screw stops in the throttle control lever; in this case, the accelerator pump drive lever should barely touch the plunger.
5. If necessary, use nut 1, which determines the start of fuel supply by the accelerator pump, to achieve the desired result.
6. Using the adjusting screw 2 for fuel supply, achieve a gap between it and the accelerator pump cover within 3.5±0.2 mm, thereby ensuring the required fuel supply by the pump, provided that the fuel is supplied uniformly by its nozzles.
7. If there is any doubt about the correct performance of the accelerator pump, remove the carburetor.
8. Secure the fuel tank 2m above the carburetor and connect the tank hose to the carburetor inlet fitting.
Information copied from the website: mercedesman
9. Place a measuring cup under each carburetor chamber and check the performance of the accelerator pump for 1 cycle by slowly moving the throttle control lever all the way to the stop several times. To increase the pump performance, turn out the adjusting screw 1, and to decrease it, turn it in.