drop the tank and get rid of that pump. the best thing you can do is exactly duplicate the benz fuel system, no restrictions, nothing that could impact diagnosis for engine issues.

there have been numerous examples of people trying to work around and around an in tank fuel pump they just dont want to remove, and ultimately it was some characteristic of that pump that caused all their problems. i say run the motor off a pop bottle in the engine compartment, if it works, get rid of that fuel pump.

i have personally seen an example where an in tank pump was connected to the return line at the top of the tank with a poppet valve for some gasoline reason. what would happen was the lift pump on the diesel could pull this poppet valve open and draw air. result was at half a tank the vehicle would run out of fuel, as the return line was much higher.

sounds like a cool truck, post some pics!
i wonder how the 617 does moving that size truck and 4x4 system around, should be fun on the first test drive

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