Loose battery connection, charging system not charging, new battery bad would be my first places to take a look at.

 

I have an 06 pathfinder. a few weeks ago it wouldn't start. It was thought to be the fuel pump, because when we hit the fuel pump with hammer or kicked it, then it would turn over. So my 18yr old brother said he could replace it. he is in vo-tech. He said it was easy to drop tank and put new one in. So I let him.
Well it went smooth going. Until he went to fill the tank back up. Gas kept shooting out, or you had to go really slow, and it kept clicking off. the Service engine soon light came on. So we assumed it was pressure. My brother hasn't had the time to drop the tank, and its really starting to drive me nuts. it takes forever to put gas in it. and I keep running it practically empty, in hopes he will drop the tank and fix.
Then today, it wouldn't start again. Wouldn't you know, I hit the fuel pump with hammer, and it started up.

So now I have 2 problems.
1. filling my tank. What could be that problem? I suggested maybe the pressure tube was pinched and couldn't relieve pressure. but my brother didn't see how that was possible. Then someone suggested that the flapper on gas tank was broke from when he shoved a tube down to suck out gas to drop tank. If thats the problem can you buy a new flapper? Any other ideas on why this would happen.
2. New problem is its back to not starting unless you hit the fuel pump. but since its a brand new fuel pump, thats not the issue. Could dirt or rust be clogging the fuel pump, and then when I hit it, it knocks it loose?
I know nothing about fixing cars, or was even there when my brother did this. I'm just looking for suggestions to give my brother so he can figure it out. if he wants to be a mechanic he needs to figure this stuff out. but I don't want it to be at my expense?

 

You say you have power but it wont start. When you turn the key does all the power turn off? If so double check your connections. Any kind of corrorison is bad. I would remove the power connections to the battery and clean both the connectors and the battery terminals with a wire brush. Re attach and clamp down tight. They should not move. They may look good and power your radio, lights etc, but when you turn to start, the connection is not tight enough for the amout of juice that the starter draws.