I followed this video how to get to, and remove the pump:



I have just performed the PCV Valve parts replacement, which is a major pain in the neck requiring the partial removal of the High Pressure Fuel Pump. Unfortunately, my GLK350 (M276 NA) will not start immediately after "finishing" work. The engine turns over, and even seems to spark for a second, but never idles. I have a feeling I am missing a step for either resetting a fuel cut-off switch, or purging air from the fuel line. Please help with any suggestions of how to move forward. I did just disconnect (unbolt) the fuel lines from the pump and the passenger side fuel rail without any prior "decompression" or "computer setting" steps.



Fuel Rail Pressure while cranking: 202 psi

Picture from Carly App Screen (Do not get Carly, it sucks for most of the things needed)

https://photos.app.goo.gl/mdFCMaHNiSenTKDT8

Fuel Rail Pressure while idling: 2164 psi (Taken prior to start of work)

https://photos.app.goo.gl/hZB7VneNWuBpsFry9

 

Any Luck figuring out the issue?

 

I had made a mistake assembling the pump. What issue(s) do you have?

 

It was a hard crank but never a start, for a while the sender would not allow fuel to fill the pump. I eventually started getting loud whining noise, which ended up being the PCV valve replaced it. I don’t know if it dislodged something in the lines that affected the high-pressure fuel system, but replace the fuel pump which didn’t offer any solution. I replaced the flex fuel sensor, both the pump and sender unit, The Plenum and after all that still no start. I thought to myself after all this time and how many times I’ve had to open up the fuel tanks surely had to have some type of objects or debris falling into those tanks. I got a high-pressure air air compressor from the lines towards the fuel sensor with the fuel sensor off and cleared any remaining debris, put back together the pump by putting fuel inside the fuel pump before installing and locking the tanks up. It cranked up better than it ever has and fired right up. it’s been an ongoing battle I’ve Been able to tolerate and deal with, but once I got to the point where I was losing all high fuel pressure to run I’m not a certified mechanic by any means, but it might be worth simply clearing the lines from the tank to where the flex sensor if you have a sensor like that it could’ve avoided me multiple unnecessary estimates of what could be wrong.

 

You are referring to "High Pressure" system, but also "in the tank". High pressure pump (2000+ psi) is mounted to one of hte passenger side Camshafts, right on the engine (M276). The low pressure pump (~200psi) is the one mounted in the gas tank. Are you sure you are addressing the correct pump. You can look at the video at the beginning of this string.