Fuel pump duty cycle issue

[Mach1soldier]

So I have an 03 mach 1 mustang that is completly stock engine wise except for long tube headers, x pipe, dumps and a tune.

I was at 91% duty cycle with the factory pump so I installed a focus fuel pump with no other modifications and now i'm at 100%. I don't understand this and really can't afford / justify going back to a return system. The tank is completly full. Also I got a code for p0190 which is fuel rail pressure voltage error or something like that but I'm assuming this is all related. The code came on when I was datalogging below.

Any help would be appreciated.

Battery voltage is at 13 volts but drops when the car is floored. I took a picture of the datalog. What the heck is going on?

 

[Ironhand]

Test your alt and battery to make sure they are working correctly.

Pull the dipstick, does it smell like fuel? If yes then replace FRPS, change oil. and go again.

Also, these cars are returnless style fuel systems, they typically will spike between 88%, 100%, and 114%.

Im not sure if what your seeing is normal either as Ive only done logging on my return setup.

 

[Brutal Metal]

That doesn't make sense at all? when my Cobra was N/A my duty cycle was in the 50% range at WOT with the stock 110 lph pump?

 

[01yellercobra]

You have a mechanical issue somewhere. You shouldn't be pegging any fuel pumps with your set up. Check your FRPS like Ironhand said. There weren't any kinks in the fuel line when you replaced the pump right? When was the last time your fuel filter was changed?