cummins man 7

Thanks for the replies and I will do that and change all fluids and filters

The truck is new to me and the gauge was on there and Im not sure what kind of pump to be honest. Idk why the lift pump would run a full course just turning the key before bumping the starter? I noticed i had to charge the batteries so maybe low voltage and also noticed it was blowing black smoke before on start up then all this started and it turned to blue and i believe its because the lift pump ran so long before i started it up so it was all the extra unburnt fuel coming out. Another thing i have the bed off because Im replacing it and i broke the filler neck so i took it off so the two rubber hoses that go into the tank are wide open so maybe the air pressure causing something weird? Plus i think the fuel pressure gauge is shot to be honest. What do you think about it all?

I have a 99 3500 mostly stock and im not to sure what this noise is or why its this loud when i turn the key on. It seems like something with the lift pump but it stays on for awhile and is very noticable in the cab then turns off. The trucks start fine and i have a crappy electric fuel pressure gauge and when it makes that noise its at atleast 25# and then i start it and it stays right around 24-25#. I have a few videos showing the noise and the gauge but none of the noise right when i turn the key forward without bumping. It sometimes comes on for a few seconds but lately has been coming on for the full 20- 25 second cycle without bumping the starter. Can you tell me if its supposed to be this loud and why it would cycle without bumping the starter only turning the key on. Also why the pressures so high? Heres the videos http://s1226.photobucket.com/albums/ee416/cumminsman7/