I can tell you without hesitation BMW fuel pumps actually soft fail as well as hard fail. I do not know the E53 fuel pump like I know the E46 and E39 fuel pumps, but I tell people to not even bother testing fuel pressure.
At the end of the day it is not if, but when the fuel pump will fail. Yes, it is wise to replace the fuel filter, but I have yet to see a fuel filter cause the problems that weak fuel pump can and do cause.
You can use the Hidden OBC to monitor the fuel level in both sides of the tank, the drivers/left side should never have more fuel than the passenger/right side unless you make a hard right turn, but the drivers/left side should pump down quickly. With soft fuel pumps we find that the passenger/right side of the tank runs out of fuel with 1/4 tank still showing on the gauge. If this happens, the fuel pump NEEDS to be replaced.
You need to verify both pressure and volume. But given the age of these vehicles and the history of pump problems, even if it does not resolve your problem, you have headed off a future failure. I find it is actually just a waste of time checking duel pressure and volume on vehicles 8+ years old. I just replace the pump and filter.
Pump with sending unit should be around $200.
You can use this tool to find the best pricing from major suppliers -
BMW Part Number Price Comparison for Windows & Mac
If you can get OBDII Logs so Fuel Trims and other values can be reviewed along with Freeze Frame data it would be helpful.
As mentioned, OBDFusion is the App I highly recommend.
11-01-2015, 09:06 PM
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