Hello. I've got both a filter top B&M FP gauge and an in-cabin Autometer FP gauge. They show different readings of 30 psi on the B&M and 24 psi for the Autometer. What might some of the causes be?

I haven't touched the connections since the install, so assuming it's not an electrical issue, could fuel flow issues possibly cause this?

Also, if I'd have to choose one over another, which would likely be the more reliable reading?

Thanks.

A-dub

 

I just went through this same issue, I had a marshall fp gauge on my rail, and a prosport fp gauge inside the car.. My marshall gauge was reading 42psi, and the prosport was reading 52psi.. Didn't think the marshall gauge was a problem, so I ordered another sensor for the prosport.. Got the sensor replaced it and had the same issue with the 10psi difference. I was like wtf, still thinking it was the prosport gauge, I contacted prosport and explaind the problem to them,and they sent me a new gauge with a new sensor at a reduced price.. Got the gauge and sensor, replaced it and wtf still a 10psi difference. I said f#@k it and bought a new gauge for the rail and replaced that and that was the problem all along.. the two gauges are reading identical now...

I didn't think it was the gauge at the rail, because the liquid filled gauges don't normally go bad like that, but the glycerin in my gauge was leaking a little bit, so I should have took that as a sign.. Sometimes you live and you learn..

I would change that b&m gauge to a liquid filled gauge if its not one, cause those b&m tend to go bad fast, due to vibration from the engine..