Help on where to hook a fuel pressure gauge Big Cam with a PT pump

thanks I appreciate got 1 more question so I done some research bout my motor but again im completely new to trucking my background is from restoring 58-66 impalas. My data tag is missing but its a small cam nt855 specifically a shiny 290 I have pt tag could someone decode it if poss

 

im getting n series turbo after cooler 400 but don't understand the rest.thanks for your guys help

 

Someone stamped a fuel code for a NTA 400 on tag. Who knows if pump is calibrated to that or not. Many, many things get changed over time. You need to find the serial number on the engine block. That will tell you what it was built as new. Tags are missing all the time. Guys used to pop them off back in the day to hide what they really had for power.
A friend of mine just recently started working on a ‘61 Pete. It has a after research because of missing tag a 300 big cam 2 in it. He worked for Cummins for 12 years during the 80’s and never heard of a 300. Yet the pump is coded for a 350 cpl.

 

So I have been running with the gauge for a while now and it seams like this problem is getting worse but do the gauges flutter? or is something warn out and needs to be replaced?

 

Gauge will flutter with foot on throttle cruising. That is normal. The fatter the throttle shaft is set the more it will. The throttle will get real sensitive to your foot bouncing on peddle with rough road. It is normal to not read anything at idle. Only The older external fuel line 743’s will make 10psi at idle because they had more return restriction. I’ve got a #7 button and a few more spring shims over the fuel code. A high performance throttle shaft that has a huge hole in it over stock. I still cruise pulling an empty 8100lb flat bed running about 20-25 psi at 65 mph with 10psi of manifold pressure. Hammer it in high gears between shifts and it will peg the 300 psi gauge.

To get the best idea of the pumps highest pressure output you have to test the fuel pressure in a high gear under load hammered down before the governor will kick it down. If No hills to test on or Pulling an empty trailer just drag the trailer brakes a little for the test to simulate a load.

 

Ok so its in a dump truck and I live in the mountains of NC so its easy to pull a hill loaded but I have never really gotten a decent reading I only feel like I did when I had a external gauge that I had zip tied to the windshield wiper it always flutters but defenly gets worse when I am at the RPM governor