Erratic Fuel Pressure Readings

[Black Beast5059]

I have a 2019 Tahoe 5.3 with a 2.9l whipple. Recently had a shop install a boost and fuel pressure gauge. The fuel gauge is pretty erratic in the sense that at idle the gauge is constantly twitching back and forth minus 10psi of whatever number it’s reading, usually around 50psi. The owner of the shop told me that’s because the fuel pump has a pulse module. Once I get moving it smooths out but even then it’s never really one set number. Sometimes it will be at 50psi sometimes it’ll go to 65psi and I’ve even see it jump to 80psi. I’ll post a picture of the line they tapped into for the gauge. Did they tap into the wrong spot and that’s the reason for the weird gauge behavior or is it normal for a tuned modded truck like mine?

 

[LordWayback]

More than likely it’s just a low quality gauge

 

[LordWayback]

It’s a whole thing

 

[Black Beast5059]

Hm I don’t think that’s the issue. My gauge isn’t a mechanical liquid filled gauge it’s a autometer electric fuel pressure sensor powered gauge.