So I'm running VP Fuels M1 which is 100% methanol in Snow Performance system. I have the stage 3 system that has two nozzles and 2 solenoids. I recently put the system back on the car after removing it almost 2 years ago. This time I replaced the Snow Performance nozzles with nozzles from ProMeth. These nozzles are 60ml's smaller than the Snow Performance nozzles. Now after a few datalogs I've noticed a dip in my fuel pressure which goes all the way down to 1150 psi while at WOT. Also my STFT's are only in the 90's. Now I tested the system and it appears to be spraying as it should. I also tested the solenoids and they appear to be functioning without any issues. The nozzles were also removed to ensure the filters were fine which they were. The pump is 4 years old so I'm assuming it's lost pressure and it's time for another one. New Snow Performance 300 psi pump will be in tomorrow so hopefully this will fix my issue. My intake temps were dropping on the datalog approximately 28-30 degrees once I started spraying. Hopefully this will help anyone having the same issue. And yes I did adjust the allen screw on the pump to try and gain more PSI but unfortunately it didn't help out my situation.
Yup I bet your pump is toast.. be it my opinion you might consider bi-annual replacement since they are cheap.. are you braided? If not you absolutely need to replace the nylon lines if there that old as well
Your fuel pressure dipped that low (momentarily) or stayed that low during your entire WOT pull? Meth isn't going to make up 50% + of your fuel pressure I think more like 20% at best. When's the last time you changed your primary O2 sensors? I had a similar experience, it was actually after I replaced my O2's and occured a few datalogs later. It dipped for a second to about 1100. Never to occur again.
But Topher is right you should replace the pump. I replace mine every 2 years.
Im betting it had a momentary dip when the meth 1st starts pumping,, then climbs up a bit. It would be consistent with a pump that spikes up meth pressure but cannot maintain it.