About fuel pressure?
 

hello i got a fass ddrp pump and a fuel pressure gauge. my fuel pressure gauge kind of acts wired sometimes. when the truck is warmed up the fuel pressure idles at 16 or 17 psi. and when im going down the highway it stays around 16 psi.then sometimes when i ran the truck a while then at idle it idles at 20 at it goes back and for th to 20 to 25. it seems to move around alot. What would cause this. and another question my truck keeps really good fuel psi at idle and highway but its wierd it goes down to 11 psi at WOT. i wonder why i lose so much fuel pressure at wot.

It sounds like the pressure regulator is not working right.

well my gauges are all brand new.

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what is the best place to hook up your fuel pressure gauge.

at the intake on your vp if you have the 24v if ya got a 12v not sure

X2

You are losing fuel pressuse because that pump is not keeping up with the flow or demand of the vp pump or p7100 even thought 11 psi is suitable for a stock truck.The fuel pressure will go down if you plan on any mods.Make sure you have all the air out of the fp gauge.