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I am having fuel pressure dropping issues that seem to be getting worse.
Fuel system is a stock RX8 tank / pump housing but with new 3/8" feed and return lines going to a (knock off?) Aeromotive FPR.
I first went from the stock pump to a Walbro 255, it worked fine for a bit but then the pressure drop started happening.
Swapped to a 340LPH pump and still had pressure issues right away.
At first it was only happening under load over 3000rpm while driving, but now I can get it to drop on idle.
I have seen other people complain about the seat on the regulator leaking, but just wanted to see if anyone had any other ideas.
I think I fixed the problem. I took the regulator apart to see what the seat looked like for the ball and it didn't look very good. This is probably why I could hear the fuel bypassing and returning to the tank as soon as I turned off the key.
So to re-seat the ball I took some 800 grit paper and placed it over the seat.
Then I took the ball/seal and push it in to the seat with the paper in between.
I lifted one corner of the paper to hold it so it would rotated back and forth with the ball while applying slight downward pressure.
I did this about 4-5 times and the seat now fits the ball perfectly.
After re-install the pressure seems to stay where is should be and when I turn off the engine it appears to hold pressure in the lines.
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FPR Problem? 
