That's because it is being overrun

 

this has me a bit worried, getting ready to fire my car anyday. using a aem 400lph fuel pump, 1300cc and stock rail/frp... is the stock components not going to be up for the task? fuel will be e85

 

NO. Upgrade your fuel pressure regulator. This is not an S2000 thing.

 

You are using a rail mounted analog gauge or a digital sensor? 73psi with a 450 on stock fpr is crazy high. I had the same setup and was at 54psi. If you want to bump up your pressure you need to take into account the fuel pressure relief valve in the pump and what boost pressure you'll be running.

 

​​​​​​It was a rail mounted aeromotive gauge. I changed it out for a clean injection digital sensor now.

 

ah, I have the same sensor. The calibration is the same as an AEM, make sure its setup for what range it is though. either a 100 or 150psi...that may be why yours is reading so high

 

Yes I saw your post and bought one. The high reading was on the other gauge though. I think it's fine other than the npt tap leaking because I tapped it too deep. The clean injection sensor seems to read accurately and consistently so far.

 

Is it normal to see a fuel pressure increase of only about 2 psi when taking the vacuum line off? I have my pressure set at 64 psi and with vac connected it is 61-62 psi. I am used to seeing a larger jump with the stock FPR and 255 fuel pump.

 

just to update in case people search info in the future. yes the stock fpr couldnt keep up with the 400lph aem in a surge tank fed by the oem intank pump with stock injectors and pump 93. I only base this on the afrs being incredibly rich. too rich for me to drive to the tuner on so i unhooked the surge tank and drove it on stock fuel system (which was perfect as far as afr's on the aem ecu) to the tuner where we installed the entire fuel system. aem 400lph pump in a surge tank fed by oem intank pump, bosch 1300cc injectors, aem fpr. aem was more than capable of handling the flow on e85.

i also have a radium fuel rail we couldnt install because there was no way to hook it up, the banjo bolt and stock feed line bracket on my stock setup was not compatible which was a big bummer. guess i should have read the instructions better as it does state you have to buy the 04-05 banjo fitting to use the stock line and when i ordered the radium setup the radium feed line install kit was out of stock.

 

Bummer on the fitting. Radium makes nice stuff but they nickle and dime for every damn thing. I too had to make multiple orders to get my radium fuel system up and going. They are the Apple of fuel system components..

You would have to turn on O2 feedback and it would have been fine... if its on 50ish psi of fuel pressure and your ecu is thinking its on 43, of course its going to run rich