Date registered: Nov 2017
Vehicle: 2000 E55 Wagon
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
Fuel pressure drop when ignition off.
My wagon has been starting harder and harder of late, so I replaced the fuel filter with a Mahle, made in Germany. However if anything, it's gotten worse since the swap. It takes two full cycles of cranking before it erratically catches and starts running. Once it's running, it's fine and runs strong.
I bought a fuel pressure gauge to check what was up. Once you the car started the pump seems fine, hitting over fifty psi when running and not dropping when revving the engine. However when the car is shut off, pressure drops away very quickly, hitting 0 psi in something less than a minute. My understanding is that pressure is supposed to stay up. I'm presuming a lot of the reason for the poor starting is related to this. Some earlier research leads me to believe that the ecu is expecting there to be residual pressure and not running the pump constantly before starting, but I'm not sure if that's actually the case.
I've looked around the obvious areas for gasoline smell or puddles of fuel indicating an outside leak, but nothing seems apparent. My next step is to pull some plugs and look for fuel, in case of a leaky injector. Any other troubleshooting suggestions? I'm trying to avoid throwing parts at this.
Also, is there a good diagram/explanation of the fuel system online somewhere? I feel a less knowledgeable about how this is expected to work than I want to be.