Help-1974-450SLC

[jim16671836]

I have a 1974-450-SLC and the fuel pump comes(for about 2-3 seconds) on each time the key is activated. then the pump shuts off. I laid under the car and listened and the pump did exactly the same thing time after time...I had just dismantled the pump and cleaned it because it had been idle for some time....it is almost like a timer is hooked to the elctric fuel pump....thanks Jim

[Pili380SL]

I believe, without a manual, that the 2-3 second start-up is a timed primer for the fuel system. Beyond that, I believe Mercedes uses an RPM reference to activate the pump, while most American cars use the oil pressure sending switch as a ground for the fuel pump circuit, as a safety check that the engine is indeed running.