1990 Mercedes Benz 190e STALLING OUT

Hello I have attached where each hose goes from the regulator. This should help you out there. Next, you need to check the pressure on your fuel pump. It sounds like it is that to me with that many miles. If you do replace it change your fuel relay also.

The primary-pressure regulator maintains fuel supply pressure to the fuel distributor and injection valves. The control pressure must be held constant, even when fuel delivery from the supply pump, and injected fuel quantity, vary considerably. This is due to the fact that any variation of the control pressure has a direct effect upon the air-fuel ratio. Fuel enters on the left; on the right is the return fuel connection from the fuel distributor. The return line to the tank is connected at the top. When the fuel pump starts, fuel pressure forces the control diaphragm downward. The pressure of the counterspring forces the valve body to follow the diaphragm until, after a short distance, it comes up against a stop and the pressure-control function begins.

Fuel returning from the fuel distributor now flows back through the open valve seat to the tank along with excess fuel from the control system. When the engine is switched (OFF), fuel pump operation stops and the system pressure drops. As a result, the plate valve moves back up again and pushes the valve body upward against the force of the counterspring until the seal closes the return to the tank. The pressure in the system then sinks rapidly to below the injection-valve opening pressure with the result that the valves then close. The system pressure then increases again to the value determined by the force of the fuel accumulator spring.