Engine cranking but not starting?

2007 MERCEDES BENZ R350
235,487 MILES • V6 • 2WD • AUTOMATIC
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BLESSING EWOBOR
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The engine of the vehicle is cranking but not starting, the engine was scanned for diagnostics trouble code, but no code was available. It was observed that fuel is not supplied to the engine. I energies the fuel pump with external battery, the fuel pump was working. However, while cranking the engine power was not available at the fuel pump. If the fuel pump connector is disconnected and probed while cranking, it will display 10v, immediately it is connected no voltage will be available to the fuel pump any longer. Removing the connector to the fuel pump and supply eternal battery voltage, then crank the engine, the vehicle engine will start running.
What could be the problem?
Could I get a wire diagram for it?
All the fuses have been checked and confirmed okay.
Thank you
Dec 16, 2024 at 10:02 AM
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STRAILER
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I have seen the MAF sensor failure and cut off the fuel pump for safety. If you unplug it and the engine starts, then you know that is the problem. Here is a video to show you how and I have included the sensor location in the diagrams below.

https://www.youtube.com/watch?v=lXLJbuAZ4CE&t

Here are the fuel pump wiring diagrams as requested. Check out the images (below). Let us know what you find.
Images (Click to enlarge)
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Dec 17, 2024 at 11:42 AM
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BLESSING EWOBOR
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Thank you very much.
Dec 17, 2024 at 5:32 PM
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STRAILER
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You are welcome, please let us know what happens.
Dec 18, 2024 at 10:01 AM
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BLESSING EWOBOR
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Yes, I will let you know.
Dec 19, 2024 at 11:07 AM
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BLESSING EWOBOR
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Hello,

The problem was the fuel pump fuse (fuse No 57), I used multimeter to test for continuity while testing the fuse initially and there was continuity. Pulling out the fuse later from the fuse box confirmed that the fuse has heat - up, the terminals even pulls into the fuse box. Replacing the fuse solved the problem, the engine has started and running fine. Does it mean that continuity is not a good way to test for fuse.
Dec 21, 2024 at 2:25 PM
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BLESSING EWOBOR
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The mistake that I did is that measure the continuity on the fuse without removing it.
Dec 22, 2024 at 8:31 AM
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STRAILER
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Usually that will work, it might have been a bad connection, did you remove the fuse and inspect it? Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
Dec 23, 2024 at 1:09 PM