Hello, new member here to the forums. But i have been tuning in for some time. Big respects to the MB community and (konigster) i believe is his name. So im currently in a similar situation, crank, no start. Checked both fuse and relay & both seem to be good. New crankshaft and camshaft sensors. Batteries both seem to be in good condition as theyre both fairly new. Also have the main battery in the trunk on a maintainer.. No codes on the ecu or tcu. New injectors, New fuel pump + sender unit. Seems like I'm able to actuate the fuel pump relay via scanner. But I don't think the fuel pump is recieving the "prime" signal from the sender unit because I don't hear anything coming from the rear bench area where everything's at. After replacing everything I ran another scan again but nothing.. the only thing I really haven't done is check for pressure up on the rail with a pressure gage because I can't seem to find mine. But I did gather some information from my scanner which reads as follows: 017 Fuel Tank Pressure difference (USA); VALUE= -33.33mbar, from the ECU, while key cycled in position 2. And, 617 Fuel Tank Pressure difference (ADC) (USA) 1.33v

Not sure what to make of all this information as that's all I was really able to gather since it cranks but won't start. Outside of what ive already mentioned here i have some other codes & canbus communication issues that i doubt are even relevant here. But who knows.. there seems to be voltage on the rear Sam. I believe I also have power up on the driver side front Sam under the hood. But not too sure about the other Sam inside the driver side dash or the front and rear prefuse boxes. Not really sure where to go from here or what else to look for but any information would really be appreciated as I don't want to keep throwing money into it. By the way it's my (W211) 2003 E500 V8 we are talking about here.

Also wanted to add that i tried to bypass the fuel pump before changing it by pouring fuel into the throttle body and it turned on for a brief sencond then shut off. So im wondering how I can "bypass" the fuel pump/sender in the sam? I guess my question is how did you guys jumper the relay to bypass the fuel pump? I'm pretty sure it's just a simple jumper wire. But if you have any pictures or can be more specific on how to accomplish that it would really help. Thanks in advance !!

 

You should certainly check the W211 forum. I found this on YouTube, could be your problem.

 

Okay so if you look at my post I mentioned how this is a crank, no start situation. So I already changed the fuel pump + sender unit. That should rule out those plastic hoses + ive already watched that video so i kept a good eye on anything plastic. So I don't think that's the issue. In addition I've changed out the the crankshaft position sensor + the camshaft position sensor. Both batteries are new and have the rear main battery on a maintainer to ensure proper voltage. No relevant diagnostic trouble codes from what I'm seeing. Moving forward today I went out to see if I could pull up any new information/ codes. I started by running a quick scan (nothing new) there. Meanwhile I was at the rear bench testing the connector harness to the sender unit for power by backprobing my multimeter. Came up with 0- volts.
Made sure the key was cycled back n forth to position 2, no voltage/power. Also went up to the engine bay and tested the fuel rail for pressure by pushing in the Schrader valve and absolutely NOTHING came out of the fuel rail not even a drop. So needless to say there should be no pressure (psi) there on the fuel rail. Most importantly I'll highlight my first post there is NO "prime" going on. Although I'm able to actuate/activate the relay via scanner. I'm not able to hear, feel or sense any signal priming back there. Yesterday I wasn't able to make that conclusion as it was a very windy day. But again, this seems like a signal is not being sent/received. Maybe due to a power issue..? Not exactly sure what's going on or what to look at next. I have a really crazy suspicion that maybe just (maybe) the 4 big red power cables that go into the rear prefuse box (f33) might be connected wrong. I believe it houses fuses #78-81 or 82. Not exactly sure what it controls although I have looked at the fuse diagram. I can't seem to find a wiring diagram showing which power cable routes/connects to what part of the prefuse box. The prefuse box was also unplugged a while back due to a battery drain issue so I believe the cables may have been mixed up.. not sure if this would cause that or anything like that. But just a thought.. if anyone else can chime in that would be great. Really appreciate your feedback too boss 👍🏼 anything helps in all honesty because what might not help me rn might help me down the road or someone else even.

Anyways I can upload my diagnostic report if anyone thinks that might help. Although I don't see any current codes on any of the modules like the ECM or TCM, CGW, SBC, ECT. The drive authorization seems to be active. Not sure where else to look 🤦‍♂️ maybe a bad ground or something idk? But wouldnt that kick up a code..? BTW I'm using a pretty decent scanner. Its the LAUNCH creader version for BENZ. It's actually really capable of doing a lot more then most for the $ invested. You can access all modules and even do some variant coding/programming. I didnt think that would really be possible until I was FINALLY able to get rid of some SRS codes and access some other things but thats another day and another story. Just wanted to add that incase anyone is wondering what I'm using for diagnostics.