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Maybe I am missing something.  Are you doubting your gauge?  Do you have the option of putting a mechanical test gauge to verify your in cab readings?  I don't see much movement on my needle and a mechanical test gauge shows the same.

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9 hours ago, notlimah said:

Well drive into work showed the following numbers.

19psi @ startup and idle - showed 0 deflection even under load with grids cycling.

20-21psi while driving - showed practically 0 deflection even while hard acceleration.

I'm really wondering if I'm really just getting that solid of numbers? I might crack the needle valve a TINY bit more to see if I can get the gauge more responsive and see if that changes my numbers.

 

I see very little variation in my readings as well and my numbers are very close to the ones you're seeing. 

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So I managed to snap this video, it's not the best quality (shaky! My trucks not as smooth as I thought! ha!) but it at least shows my fuel pressure spread. I'm really surprised that my fuel pressure spread is as low as it is! Overall, I'm really happy with everything!

 

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40 minutes ago, dodgedieselnewbie said:

I have a question and will post it here rather than start anew... Why do fuel pressures vary? If two trucks are running Fass 150s.. why would one show 16ish and one 20ish? Is there an adjustment?

Could be multiple things.

-fuel line size

-using stock fuel filter as well

-return line size

-the spring in the FASS itself 

40 minutes ago, dripley said:

Was any of that run at WOT? I did not see but maybe a 1 psi drop.

No wot on that run, probably 1/2 a 3/4 throttle though. I'll do an official wot run soon

 

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7 minutes ago, dodgedieselnewbie said:

Okay.. all things being equal.. 1/2 line.. no stock filter... that leaves the spring.. right? I heard it can be stretched/adjusted.. changed?? I mean.. ultimately you want the highest pressure you can get/supply.. no?

Not neccesarily. Like IBM said, you can see starting issues. You could also cause issues to your VP. It's not really a more the merrier type thing. You want the sweet spot of 15-20psi. More then 20 isn't needed and obviously under 14 and your overflow valve isn't working.

I'm not sure how much the return line matters in the overall psi, but maybe that could be a difference as well.

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Late to the party....  As for needle valve... I open it up til the start up and shut down bleed time is really quick, and then listen for a buzz of the vp pulse hammering the gauge and tighten as required.

As for overpressure, I believe mopar man debunked that unless you have an old stock dodge vp with the plastic in it.  The new ones are steel.

I think my fass needs a new set of brushes and I would like to up the pressure.

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One of the things liked about the ADII that bought is the adjustable pressure regulator. I did not want to mess with a spring and such. If I want a change just loosen the lock nut and adjust as necessary. Not sure why more of them dont come that way. I have mine set at 18.5 at idle and see for the most part a 2.5# drop at WOT. If I set the comp on 5 and hold my foot in it I can pull it down to about 15#'s. by then I am going faster than I need too.

 

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Well I went out a recorded some fuel pressure videos. Here they are...

 

 

 

Overall I'm extremely happy with this setup. It idles around 19-19.5 and I couldn't get it to drop below 18 at WOT. So at worst its a 1.5 psi drop! I'll take that any day!
 

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