Question fuel pressure swing

[robinson]

Put a gauge on fpr it swings real bad between 35# and 55# every now and then it will hit 70# is this normal or should i shim the fpr spring. Just tring to help mpg it seems to have gone down over time. It is 95 F350 7.3

 

[Cratos]

machaical pumps look that way since they pulse

 

[95_stroker]

I'd say you are normal, perhaps a little low on the fuel pressure but nothing to be alarmed about. If you want to accurately read the pressure you need a liquid filled gauge to dampen the pulsations.