Fuel pressure jupy??

[Turbo_pace]

Well I just put a gauge on my truck in place of the shredder valve and when running the gauge jumps around between 40-60 real fast, what is this an indication of??

[JSchuricht]

It's a mechanical pump, it's going to jump around.

[Patrick Feeley]

It will jump around due to the nature of it being a mechanical fuel pump. A liquid-filled gauge will dampen that somewhat, but don't leave the gauge on there permanently as they tend to get hammered pretty quick! Cheers!