New return fuel system: slight pressure bounce at idle?

[fbody83]

Hey guys, I finished up installing my new fore return style fuel system last week and noticed that the needle on the fuel pressure gauge is bouncing a little at idle. This seems to only start happening once the car is warmed up. Is this normal? I'm not having any fueling issues when driving the car.

The setup is a -8 AN feed and return line through a fore 4 port regulator in the fender with separate lines going to each rail (dead head).


[youtube_browser]0-6gMAczneY[/youtube_browser]

 

[Tractionless1]

Fore is very helpful, give Justin a call. My F2i regulator doesn't do this running -8 supply to reg. -8 single supply to OE rails, and -6 return from reg., I.E., deadheaded as well. My gauge reads off the regulator though rather than the rails.

 

[cj428mach]

mine is read at the regulator and is rock solid. Maybe being on the rails you get a momentary drop in pressure as the injectors fire?????

 

[Bdubbs]

Well after doing some fair amount of research on fuel pressure regulators, it seems that there accuracy is hit or miss. Once the gauge or the liquid inside gets to hot the accuracy can be diminished. I've found this problem with mine at least. Sometimes it will read a 10 psi difference. Every day is different. I thought about trying a different gauge for the heck of it. Here's an article I found.


http://aeromotiveinc.com/fuel-pressure-gauges-liquid-filled-vs-dry-problem-solution/

 

[fbody83]

Thanks guys. I spoke to Justin Fore and he explained that this is normal and comes from the feedback from injectors. You'll only see it when the gauge is on the rail and when you have large injectors.

He also confirmed what Bdubbs said - The mechanical gauges aren't 100% accurate and this accuracy gets worse as the fluid in the gauge heats up.