Originally Posted by Th3Franz
You could start by hooking it up to the stock wiring and see if the pressure is high enough for your needs, since the supply current from the ECU might be limited. If not, then you can run it with a relay and run it at 100% with current drawn straight from the battery. Fuel pumps can get pretty noisy running at 100% all the time though
The first guy who wanted to adjust the fuel pump duty cycle was actually doing it for noise reduction, but the other way around. He said his pump was very noisy when running at low speed. At 100% it runs quieter. Go figure.
Anyway, I can certainly see value in running a heavy duty fuel system with a heavy duty power supply. I've seen pics of setups with three pumps and it never occurred to me until this thread that you'd probably destroy the ECU's fuel pump driver that way. Using the stock fuel pump line to drive a good mosfet (with a good heat sink) seems like a great idea.
If anyone has reason to believe that running your pump at 100% all the time would solve a problem, I can get you an EcuFlash ROM definition to make that happen. However you will first have to convince me that you really need it.
Tons of Impreza people are running Walbro 255s off the stock ECU, I'd be very surprised if that setup was really problematic.