Has anyone done this? Has anyone else had the same issues Jeff had with unstable fuel pressure? I am using the stock pump while he was using the Supra pump. However at some stage I plan on fitting a Walbro pump instead.
What i did was run a 10 awg wire from the battery to the pump. using a regular 30a automotive you use the stock fuel pump power wire as your relay trigger. you also need to do the resistor by-pass. The stock wires are very small and go a long distance so there really isn't enough power getting to the pump under stock wiring. I can't feel the transition from low speed to high speed anymore and its a lot smoother.
If you ever upgrade your pump you might over run your stock fpr and then all you would need is an aftermarket fpr. I don't think a walbro would overrun the stock fpr if its still in good conditon
2007 BMW 335i 6MT BLK/BLK 1995 3000GT VR4l SOLD l
1992 3000GT VR4- SOLD
Last edited by soccermania688; 07-18-2010 at 07:44 PM.
I just did this yesterday... so it's funny to me that this thread pops up
My fuel pressure has been high for awhile. I already had the resistor bypass mod done. Here are my before and after numbers.
11.23V Cold idle
10.76V Under boost
11.07V Hot idle
13.91V Cold idle
13.96V Under boost
13.95V Hot idle
Battery voltage: 14.09V
Obviously, the mod kept the fuel pump voltage very stable. Before it was done, voltage would DROP when it was needed most... under boost.
I ran 10AWG from the battery back to the pump. I thought about using 8AWG but went with 10 because Hosfelt didn't have 8AWG and they were VERY cheap. My install is VERY clean and I am quite satisfied with the results.
Fuel pressure is even higher now at around 50psi. Coming up next for me is an AFPR. On the plus side, my injectors flow more at 50psi... so I might even be able to go higer than 14psi of boost.
BTW, the Erik Gross method isn't the way to go... even he himself has stated high fuel pressure after doing it his way.
I did the rewire in may with a 40amp relay. I have sufficent amps to the fuel pump.
Running a 255 without an FPR (I need one like Xtreme does)
kwikwire.com sells a kit for this for like $25 if you don't want to do it custom tho..
I'm running stock boost [with free boost mod] atm and don't intend on increasing it until I have a Walbro 255. In this case I would fit an aftermarket FPR at the same time. Depending on finances I might fit the FPR sooner rather than later.
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