I recently installed a 75mm pro-m calibrated for 30lb injectors, 30lb fms injectors,255lph in tank, afpr, and a gauge. Combo is pretty basic, only a b-cam, cold air intake, underdrive pulleys, no smog equipment, offroad h-pipe, and 2 1/2 flowmasters with dumps.Timing is set at 11* with spout out for nitrous use. I installed the 30lb setup getting ready for my upcoming turbo install. My question concerns the fuel pressure. If I set it to 40 or so, the car idles very rough and does not accelerate well. It will spit and sputter and rev very slowley under a load. No load it tends to back fire. If I raise the fuel pressure to 60-65lbs no vacumm, it runs like a top with no problems and seems to have more power than before. I bought the pro-m and the injectors used. Any and all ideas will help. Also, the gauge is about 16 inches from the schrader vavle if that makes a difference.
Have to run high fuel pressure
- Thread starter getusummm
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is your fuel pressure guage known to be accurate?? if you know someone else who has a mustang perfable with a stock regulator hook your guage up to there car to make sure it works(should be around 38 psi). you can also try kragen auto parts store to see if they have one to loan out. also for fun check your timing. chris
Well we dont have kragen auto parts down here in Louisiana, lol. As far as the timing, I have double and triple checked it, spout out. I expected the car to not run quite right with injectors that are too big, but the high fuel pressure puzzles me. I am somewhat curious about the gauge. It is not an actual "fuel pressure" gauge, but rather a brand new, known to be good 160 psi gauge from an air pressure regualtor. Could that make a difference? Everything I have read tells me that a "gauge is a gauge". I couldn't find a difference between liquid versus air gauges. Even the guy at the FMS counter told me that would be fine.
Gauges are gauges - fuel and air will work the same and give the same results. There no such thing as guage for liquids and and a gauge for air or gases.
I have a cheapo industrial gauge for my FP gauge and it works fine. See http://forums.stangnet.com/showthread.php?t=588569& for more info
I have a cheapo industrial gauge for my FP gauge and it works fine. See http://forums.stangnet.com/showthread.php?t=588569& for more info
Well I tried a new gauge today, same result. Tried cleaning the MAFM, no real change. But low and behold, when I rotated the MAFM 90* towards the alternator, problem solved. FP is back down to 38 right now and idles as smooth as can be and drives great. Maybe on the rich side, but acceration is smooth with no popping, stumbling, or surging. Now on to more productive things like fabbing up the turbo system. Thanks goes to you jrichker. I found this suggestion in a couple of your replies to other problems.
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