Green5pt0

Hey I put an adjustable fuel pressure guage on and I have it set at 42psi with the vac line dissconnected. I seem to have lost ALOT of my bottom end, and it even backfires at low RPM's in higher gears. Am I correct in assuming the fuel pressure needs to be higher?
Any info is greatly appreciated! Thanks alot,
-Green5pt0

primetime5.0

https://mustangforums.com/m_463668/tm.htm

Green5pt0

I checked out that thread and It helped somewhat, but with my engine acting the way it is would you say I should turn the pressure up more since its not running well at 42?
Thanks!

91LXstanger

well 42psi is about as high as i would go.

Green5pt0

I know what you mean LXstanger, but the fuel regulator is the only change I made to the engine and now its not running right. The symptoms seem to be saying that it needs more fuel, but 42 is already alot... Could too high fuel pressure be giving me the problems I'm having? Thanks for the feedback!
-Green5pt0

stanglx2002

i would say back it down to 40 psi and see if that makes it better and are you running rich?

Crash7772

Did you change the FPR from stock to adjustable and add a gauge? The best way to tell is a dyno pull with a A/F readout. Are you still running the stock 19# injectors? You can run up to 60psi on the injectors but I personally wouldn't recommend it. Any idea of what HP your making? Did you know what the psi was before you changed it? When I did mine I added the gauge first then a day or two later added the adjustable FPR. The stock one was actually running 40psi and after a dyno pull 38psi was the best for me but I was pretty much stock at that point.

Djs94stang

Let's back up a bit....why did you increase the fuel pressure? Did you change the cam/intake/exhaust...all of the above?

Green5pt0

I have a K&N cold air intake, 70mm TB, 70mm MAF, trick flow street intake, BBK shorty headers, offroad h-pipe, and 2-chamber flows. My timing is set at 18 degrees and I run 93 octane. I have an A/F guage and a fuel pressure guage on the schradder valve. With the vacume line off (WOT) I'm running at 42psi. Oh yeah, I also went through a full tank of gas in about two days so I'm thinkin I might have the pressure too high! Any suggestions would be great!
Thanks alot,
-Green5pt0

Crash7772

With your mods I would try 38psi with the vacuum line off. You could try 40psi but I think 38 will get you where you need to be.