Vehicle is a 1999 ML 320 with about 152K on it. First fuel pump was replaced under warranty, second by my and now I need another. Actually it's not the fuel pump that fails but the sending unit.

Are fuel pumps with built in sending units considered consumables like oil filters, oil, brakes, battery and the like?

The most common reason for sending unit failure is ethanol ratio in the fuel you use.

When the ratio gets to 90/10, (10% ethanol) fuel sending units tend to fail.

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Oddly enough, the sending unit on my 2001 went tonight as well, gauge slowly went to empty after a fill up. Mine was replaced in 2008!
Any service bulletins? Recalls?

Additionally, is the $435.00 part the only option?

Other questions, there are 2 options for the assembly, one is an "updated" 3 hose the other is a 2 hose, how can I tell which one is in there before I order it, is it on the top or do you have to pull it?

I have read that there may be no reason to replace the filter also, any thoughts on that?

Appreciate it!

-John

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John
2001 ML 320
1988 560 SL
2009 Toyota Tundra TRD
1992 400 E (sold '07) (bought back, '13)
2008 ML 350

I replaced my fuel pump relay and haven't had a single no-start since... coincidentally, my 194k mi fuel pump has never managed to fail...so I guess I'm the lucky one. Anyone think it's worth the $15 gamble (from the dealer!)?

I ordered Bosch pump with sending unit from Phil yesterday. I paid for overnight next day delivery so it came today. I replaced that unit and also put in new fuel pump/regulator. I also replaced all three hoses as they are more trouble than it's worth to remove, and I have the Hazet special tool to remove them.


Vehicle had also been throwing P0455 code. When it gets between 3/4 full and 1/4 I'll just have to see if it keeps throwing that code. If so I'll have to take it to dealer as I do not have any sort of smoke machine to check for vaccum leak.


I friend of mine who works at independenat MB shop said that it was possible that the full pump might have been causing P0455 code, something to do with pressures, did not quit follow theory.


Edited:
Cost of bosch pump with sending unit from Phil was $162, with overnite shipping was about $200. Well worth the price form my perspective.