just installed stewart warner fuel pressure gauge at the schrader port on vp pump,bleed air from line and gauge showed 14lbs with no load,6lb at wot.
pulling my enclosed car trailer{about 7000lbs)shows 10-12 lbs at 1900 rpm.
but sometimes the gauge shows 0-1.5 lbs just cruising and if you kick it down will jump anywhere from 3lbs to 15lbs-might stay there or go back to 0-1.5lbs.If I turn truck off and get back on the road pressure comes back and stays 10-12lbs.No codes in computer,both pumps replaced at 90,000 mi by dodge,truck now has 145,000mi.Any sugestions?

 

I do have a needle valve in the fuel line to the gauge,it is open all the way.
Brent

 

I had the same issure with several Carter-Style pumps (six to be exact).
Fluctuating pressures......

I ditched the Carter pump and replaced it with a Walbo/Glacier Diesel setup.
Others have used different style pumps from different manufacturers.

Basically, if you want to SOLVE the problem, trash the Carter-syle lift pump.

 

What kind of pump did the dodge dealer replace it with?? They didn't do the dreaded intank pump did they? I had the lift pump on the block and at 98k it went south. Dodge replaced it and the IP. At 148-149k my intank pump took a great big shuddering dump. Installed a Fuel Boss from Glacier. Talked to a guy who works at the local Cummins shop, he said those intank pumps were the most useless pieces of schmidt, said they have replaced intank pump conversions on 2nd gens with 2-3k on them. He told me that mine is one of the longest lasting one's he has ever heard of, and this is big Dodge country around here.

You have it hooked straight to the fp guage? No isolator or anything? Those Dodge electric fuel pumps are amazing, great engines and trucks, fuel pumps aren't worth spit.

 

I moved the pump back to the frame just in front of the tank and put a NAPA inline filter in front of it to keep dirt from getting into the valves in the Carter FP and preventing it from working properly. Pressure came up a couple lbs.