I figured I would compile this data in one thread as I am getting some questions. There is more info in this thread
http://www.e90post.com/forums/showthread.php?t=517288
but all pics and videos have been consolidated in this post
I got a few photos that you guys might be interested in with all this fuel pump talk. BMS is setting up a fuel pump voltage booster for one of their customers and took a few photos showing the fuel pump location, connectors, and contacts. The main power connector should look familiar to many of you!
The DME runs 14 volts and varies its duty cycle to change pump speed. At full duty a volt meter will show 14v. At idle a volt meter will show around 7v. The voltage hasn't changed just the ratio of how long it was applied (e.g. the duty cycle). Here is a video showing the actual N54 low pressure duty cycle. This is why you use a real scope for investigative work before writing the white paper.
The question was asked on another forum what does the DME and FP controller do if you just unplug the low pressure sensor. Here are the results.
Little update with flow testing at various voltages for you guys.
Quote:
Had a chance to do some exploratory flow testing with a new stock pump generously on loan from RB. For this testing I used a simple rig. A variable voltage XP800 power supply, AM regulator set at 72psi, an iPhone timer, and an empty 2 liter bottle of diet coke. Each voltage was tested 2-3 times and averaged. Std deviation was quite low.
Based on the testing @ 14v, the factory voltage, I came up with a theoretical whp curve. But the important thing here isn't the measured LPH or my theoretical power estimate. It's the flow and current variance at each voltage. Based on this testing I'd say this pump is an excellent candidate for increasing flow via increasing voltage. Which isn't surprising but always nice to verify.
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