Genuine Mercedes 1770700501 Fuel Pump, Mechanical; Left – Mercedes

The mechanical fuel pump on your Mercedes delivers fuel to your engine’s carburetor to run the engine. The mechanical fuel pump is mounted to the engine and is run using a pushrod that transfers camshaft movement to raise and lower a diaphragm inside to pump fuel from the fuel tank up to the engine. Since the mechanical fuel pump uses camshaft motion and a pushrod to operate, it will only pump fuel while the engine is turning.

If the fuel pump diaphragm ruptures or the fuel pump arm sticks, the fuel pump will not pump gas to the engine and the engine will not run.

Signs of a Faulty Mechanical Fuel Pump
A lean running engine, engine stuttering, and engine stalling are all signs the mechanical fuel pump on your Mercedes is beginning to fail. Either the diaphragm has a small hole or tear in it that prevents the pump from pumping all the needed fuel, or the pushrod lever is worn. If the diaphragm is completely torn or the pushrod shaft is completely worn or broken, the pump will not be able to supply any fuel and the engine will not run.

Replacing Your Mercedes Mechanical Fuel Pump
The mechanical fuel pump should be replaced anytime it cannot supply adequate fuel pressure to the carburetor to run the engine. A vacuum pump can be used to test the draw of the fuel pump while the engine is being cranked to determine how much vacuum is created. If the pump does not create a vacuum or the vacuum created is less than specified in the Mercedes owner’s manual, the pump has failed or is failing.

Mechanical fuel pumps mounted to the side of the engine can usually be replaced in under an hour. However, make sure the mating surface to the engine is properly cleaned prior to installation of a new pump to prevent vacuum leaks that will prevent the pump from pumping all the fuel needed. Additionally, replacing the fuel filter inline before the pump will prevent fuel contaminants from damaging the diaphragm on your new mechanical fuel pump.

Mercedes Fuel Pumps.