I just replaced my fuel filter yesterday, and I thought some of you might be interested in my findings. Big thanks to Mik325tds on activating the LPFP with Toolset 32. I should note, the old filter was a BMW filter, and had a manufacturing date of January 2017.
I pulled the filter outlet hose off and slid on another hose with the other end into an old juice bottle, just to see the flow rate. I ran the fuel pump with tool32, and I was unpleasantly surprised by my findings.
Next, I removed the old filter and heater, and just ran the fuel pump with the unfiltered fuel going into another juice bottle. Also rather unnerving findings.
After that, I hooked up the new fuel filter, ran the pump, and collected the fuel while the new filter was priming.
Finally, I ran the pump with fuel flowing through the new filter and into anther bottle.
A picture is worth a thousand words, so here are the 4 bottles side by side. Notice the color, clarity, and volume difference between the old filtered fuel, unfiltered fuel, and freshly filtered fuel. Note: The pump ran the same duration for each test, so volume in each container is directly related to filtration, not pump duration. Not only is the fuel through the old filter nearly half the volume of the freshly filtered fuel, but it looks as though the old filter is actually adding dirt/grime/particulate/"stuff" to the fuel going directly to the HPFP
.
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Here are some pics of the fuel filter cut open. Notice the "goo" between some of the fins in the element, and brown gritty stuff elsewhere.
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I've heard that a filter actually filters better with age, since the stuck particulate acts as a finer media for the fuel to pass through. But based on my findings, I'd say there is a limit to that, and this filter was way past that limit.
Based on the unfiltered fuel color and cloudiness, It looks like I'll be doing a complete tank flush. Anybody know a good DIY thread? I might be interested in an aftermarket water separator/filter too, so I'll have to do some research there.