2014 cts-v fuel pressure dropping to 38 psi at wot

[01SLPSSM6]

Hey guys, having an issue with fuel pressure dropping at WOT. 2014 CTS-V ID1300s, DW-300 fuel pumps with the regulator that comes in the kit, (2 340lph pumps) currently 680 rwhp on E85. Vehicle had an issue with fuel pressure dropping on pump gas before the DW-300 pumps were installed, the fuel pumps were unknown at the time so i installed the DW-300 kit because my friend does not want anymore power than what its at.

I have noticed that as soon as the fuel pump duty cycle hits 100%, the fuel pressure goes to about 72 psi and it starts dropping from there, it drops to 38 psi by the time its at 6500 Rpm. I did adjust the duty cycle in the FPCM because the short term was adding, now its -3%. I tried changing max pressure regulation and a few other settings to see if that would change anything so in the log if you see that its commanding 85 psi that is why. The fuel system minimum voltage is 12.5 stock, but the FPCM voltage is at 12.0V, anyone ever try to command the alternator to put out more voltage to the fuel pump control module by changing the minimum voltage number? I have tried adjusting different parameters, but no changes. Any help is appreciated.

[hjtrbo]

Wow. You're way out of fuel pump. Your injector duty calculates to 107%. Your delta pressure is only 23psi across the injector. Scary stuff. Don't think a couple of volts will save you. Time for 2 x Walbro 460s and a manifold referenced regulator mate. Intake air temperature getting up there. Consider setting the rev limit to 5500rpm or put it back on gas until sorted. Also a bit of a lean spot that needs sorting presumably when you loaded the dyno up, around 2000rpm.

[01SLPSSM6]

The pumps should support the current power level, i wanted to install an external regulator, but he wanted to cheap out and try the $400 option lol. Something in the fuel pump control module is causing it to ramp down pressure when it is at 100% Fuel Pump DC , the fuel pressure goes and ramps down from there. Going to adjust the DC table and High/Low flow numbers and if that works. I agree only 23 psi is scary i know the fuel is probably dribbling out.. still hitting my target lambda but definitely not safe. IAT was getting up there for sure kept making dyno pulls and the interchiller does not work to well...not done with calibrating it so i will look into that.

[hjtrbo]

The pump commanded DC remains at 100% throughout. Desired fuel rail pressure remains at 85psi throughout also. You are on the high flow control loop. Read the specs on the fuel pump set up. Apparently good for 700rwhp on E85. So if its not the pumps is must be the injectors. If they're open like they are you lose all your back pressure. The kit creators mention 1000cc injectors. Is that what you've got in there?

[hjtrbo]

screen shot...

[hjtrbo]

and for comparison here is my setup with the fuel pump clearly not up to the task.

[01SLPSSM6]

Yes, it does remain at 100%, but it also seems to be the point where the fuel pressure starts to drop shortly after it hits 100%. I commanded it to be 85 psi to see if it would allow it to at least hit that pressure. I am on the high flow control loop, but i did not raise the lb hr value, i think this may be causing a problem because the fuel flow is exceeding high flow upper limit. It has ID 1300s so its definitely not out of injector at this power level, but you are correct that you cant build pressure when the injector is in saturated mode.

[blindsquirrel]

What is the voltage at the pumps, though? Commanded voltage from a computer doesn't mean shit if there's 6v voltage drop somewhere.

[HarryD]

boost-a-pump lol
kinda joking kinda not.

[BigTuner]

What are the chances only one pump is running?