Was checking my fuel pressure to see if I could diagnose occasional rough idle/surging, not sure if what I saw is normal. Reads at about 48, but needle shakes back and forth rapidly between 46 and 50. If I turn the truck off, pressure holds solid at 40. On start up the gauge needle will shake back and forth between 20 and 48 rapidly for about half a sec then hover around 48. Is this normal, or is my fuel pump going? Also the thing is loud as hell, can hear the pump whining whenever I'm outside truck while its running.

 

The only thing I can say is that 20 psi at startup isn't enough and I can't hear mine while it's running. Someone will chime in who knows more.

 

You should see 49 psi as soon as you turn the key. Any deviation from that it's time for new pump.