4 Wire Fuel Pump - WTF?

[greddy91]

Good day to you all!

I'm wondering if anyone has any idea why the 2010 X5M fuel pump has 4 wires on it? I know this isn't the only model with this configuration, so if anyone has any insight I would greatly appreciate sharing the pinout and functionality.

As it stands now I've got a spare bucket at a reputable fuel management vendor reviewing for the possibility of dropping a higher volume LPFP into the bucket to increase the E85 content past the 30% mark (or really 20% mark for me as my LPFP is crumbling it's way to death day by day).

Looking for a fuel fix for us all; any help you can provide will be appreciated!

GH

[mitch808]

Many 4 wire pumps, are because, the extra two wires are for fuel level sensing, and the larger guage wires the pump itself. Pretty evident when looking right at the pump, if that is true.

But being a BMW, I wouldn't hold it against them to make those wires some special communication CANBUS protocol, that feeds a PCM, that is connected via fiber optic cable, to move a mechnical potentiometer.. (leave it to the German's to make stuff complicated )

[greddy91]

Originally Posted by mitch808

Many 4 wire pumps, are because, the extra two wires are for fuel level sensing, and the larger guage wires the pump itself. Pretty evident when looking right at the pump, if that is true.

But being a BMW, I wouldn't hold it against them to make those wires some special communication CANBUS protocol, that feeds a PCM, that is connected via fiber optic cable, to move a mechnical potentiometer.. (leave it to the German's to make stuff complicated )

Nah the fuel level has it's own two wires. There are four wires that tie directly into the pump in the bucket.

[deansbimmer]

Most if not all of the newer BMW fuel pumps are brushless. They require at least three wires to operate and also necessitates the need for a separate fuel pump motor controller (EKP). You can't just swap them out for an aftermarket pump, which are almost exclusively brushed type motors.