A gauge is best located in a location with little or no flow, this gives an accurate static pressure reading and minimizes any error due to fuel flow over your sensing port. (Venturi effect). Error would be minimal though
hmm, I always thought the main reason you want a gage somehwere with little to no flow, is all plumbing has restrictions and therefor backpressure. If you have flow you only know the pressure where your gage is, not a few inches down the line where the restrictions and backpressure changes.
In a system like a honda where the end of the rail has a huge restriction in the fpr, I wouldn't think it would matter really where you put it from the filter to the rail as the filter would be the only other large restriction you'd have to look for, so as long as you're downstreem of the filter you'd be fine.
(same concept as if you read boost pressure at the turbo vs. at the intake, each restriction adds backpressure and your end result is lower pressure reading at the intake)
ok i guess i still dont get it. the fuel gauge on the fuel filter banjo fittings would tell me what pressure my fuel pump is pushing. not the pressure my fpr is at. so either i get a wideband or a fpr with a gauge built in? that is all
only if it was in the inlet banjo of the fuel filter, the outlet would be the same as the fuel rail. The fpr controls the pressure behind it up to the next big restriction.
(unless you're a dumbass with the banjo washers backwards like I did once and creat a huge restriction right at the rail inlet)