manual fuel pressure gauge
 

my friend has a 01 cummins and I think the vp44 is going out but I want to double check the fuel pressure getting to the vp44. I was wondering how some of you have done this? is there a port I could tap into or do I separate the lines and put a gauge in there? any help would be great....

for a temp check I did use a refrigeration gage I believe there is a 1/4 flare port to do a quick test. been a long time I am now connected to the air dog loft pump under the truck