TnF Posted September 9, 2017 Report Share Posted September 9, 2017 (edited) Hello. If you remember i added a fuel pressure sensor recently and i am running differential fuel pressure compensation on the injectors. Under WOT conditions you can see that fuel pressure starts falling from about 46-48psi base fuel pressure to 40psi and even spikes up to 52psi during the gear change. Injectors are ID 1050X, 8mm fuel lines, new fuel filter, oem fuel rail (ca18det), and adjustable fpr (unknown brand, very similar to SARD design - not the copy one though, this one is riveted). Fuel pump is Walbro 255lph HP version running on the stock nissan wiring (15A fused - stock is 10A - heard there is a measurable voltage drop in our cars).What i am wondering is this 12psi fluctuation range typical of what do you normally see, should i be worried, or is there any point of limitation in the fuel system? From the data you can see fuel flow at fuel load is 2L/min=120lph, this pump can do this flow at 90psi @12V, whereas the fuel pressure i have is much less.I am thinking the adjustable fuel pressure regulator is the "issue", too small, with too small diaphragm.What are your thoughts? Edited September 9, 2017 by TnF Quote Link to comment Share on other sites More sharing options...
Ducie54 Posted September 9, 2017 Report Share Posted September 9, 2017 I see just over 5 KPA pressure drop as an example. I find the pressure slope of the turbosmart 1200 to be very good, that's what I use. I would try a better quality fuel pressure regulator and rewire the fuel pump using a realy close to the pump with large gauge wiring. Brad Burnett and krohelm 2 Quote Link to comment Share on other sites More sharing options...
TnF Posted September 9, 2017 Author Report Share Posted September 9, 2017 Well i am thinking the same - it is either one of the 2..my idea is to datalog the voltage at the fuel pump to see if i have a noticeable drop - both could be an issue in the end though Quote Link to comment Share on other sites More sharing options...
TnF Posted June 5, 2018 Author Report Share Posted June 5, 2018 Just an update to this, the solution was to move to a more flowing FPR, i used Turbosmart FPR 800 to have a stable +-1psi fuel pressure. The issue is with a restrictive FPR all the flow from the pump increases head pressure so the base fuel pressure you set is higher than when you have less fuel returning. Either way best to use a fuel pressure sensor as i have now as well and have the ecu compensate (assuming you have injector flow data for each voltage and pressure) Quote Link to comment Share on other sites More sharing options...
Steve Posted June 5, 2018 Report Share Posted June 5, 2018 Yeah. Regulator overrun is more common than people tend to beleive. And often quite obvious when you know what to look for Quote Link to comment Share on other sites More sharing options...
Grant Baker Posted June 6, 2018 Report Share Posted June 6, 2018 We get this on stock regulators on the VAG 1.8T engine when the in tank pump is uprated. A decent FPR fixes it... Quote Link to comment Share on other sites More sharing options...
GregM Posted June 7, 2018 Report Share Posted June 7, 2018 For the price of a decent FPR, a Fuel Pump Speed Controller is something I'm considering. No need to upgrade the FPR or fuel return line, and keeps the fuel cooler. Quote Link to comment Share on other sites More sharing options...
Steve Posted June 7, 2018 Report Share Posted June 7, 2018 6 hours ago, GregM said: For the price of a decent FPR, a Fuel Pump Speed Controller is something I'm considering. No need to upgrade the FPR or fuel return line, and keeps the fuel cooler. I actually went from aeromotive fpr to stock when i started pwm'ing my pump. GregM and TnF 2 Quote Link to comment Share on other sites More sharing options...
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