I know this topic has been beat to death, but i really need some help with my fuel pressure gauge. A few months ago I purchased an Isspro ev2 fp gauge, autometer snubber, and bigline kit. I install everything, and from day one the gauge has flucktuated. At idle in continuously goes back and forth from 20-18 psi and wot 14-16 psi. After doing a little research I found many recommend that a needle valve be used. i have been putting it off because after the install a had a hard time getting the truck to start probably due to air in the lines. The bigline kit replaces the banjo bolt at the vp44 with a tapped 90 degree fitting. I installed the snubber in the tapped 90 degree fitting and the fp sender into the snubber. My question is, should I install it (snubber, needle valve, then sender) or (needle valve, snubber, then sender), or should I do something totally different. Also what would be the best way to bleed air out of the lines after I take everything back apart and get it back together? Last time I loosened the tapped 90 at the injection pump and bumped the starter until I saw fuel and tightened it back up. Any tips, insight, or recommendations would be greatly appreciated. Btw Im running Raptor FRRP if that makes any difference.

I have the same gauge and the same trouble! I have a needle valve and have it just a hair from being totally shut and my gauge still fluctuates a bit. So I hope someone can help.

Here you go... Skip the snubber install the needle valve...

As for wandering if its a electric sender then you might have to replace the sender due to being damage already. Mechanical gauges you know when youe set right because the gauge no longer is buzzing.

Thanks a lot! Should I use any thread sealant on the needle valve, or should it be ok?