99 Tahoe issues

Ok got a few slight issues with the hoe....

I think the fuel pump maybe going out on me :banghead:
When cold out, when trying to start the pump does not 'charge' / hum like it getting power. This has happened twice, 1st time it was fine next day, then a week ago it did it again, couple light taps on the tank with a hammer, it started fine.
Once started it runs a drives fine (minus another issue).
* I am assuming this is the fuel pump - How difficult is this task for a DIY'selfer?

Sometimes on startup there is a knock, this goes away after a few minutes - starts off louder then to quiet then gone....
Any ideas what this could be? I ran some seafoam thru her, and it stopped for a couple months then returned. (clogged oil gally???) could this be related to the pump???
Now I have also noticed that occationally the oil pressure gage will jump to the 40 mark on start up - then under throttle it goes to 80....
Could this be a bad sending unit (giving wrong pressure) or ??? - I dont drive her alot but I dont want to spin a bearing or anything either.

99 Tahoe 96K miles 5.7 auto 4x4

Thanks in advance

I have a 97 Tahoe and your oil pressure seems normal. Mine does that same thing. Your fuel pump on the other hand can be done yourself but you might want to have some help. You have to drop the tank. Once the tank is out, it's a piece of cake. Its just getting the tank out. Also check your wiring harness for the fuel pump carefully because there is known issues with the connectors melting and wires burning. Now you may just change the actual pump or you can change the whole unit which has the fuel gage and everything. I recommend changing the whole unit.

Having low fuel pressure will make your truck do weird things. Make sure you change your fuel filter when your finished.