Car won't start!!! Is it my fuel pump?

[gavij012379]

Hello everyone

This is my first post and I am here with a problem. Any help is greatly appreciated. It is 2002 olds alero with 2.2L engine, auto transmission with 114k. I have own it since 2003 when it had 27k.

My car won't start. This is how it started. My wife drove the car to school (30 miles away) on wednesday on a rainy day. She said the low tire pressure light was coming on so I ask her to check the pressure on the tire. But after checking she was not sure. So I told her to take it to Walmart over there to have them look at it and do the oil change too. The guys at walmart took off the inlet air temperature sensor (I don't see how that happened). So she comes home and tells me that the low tire pressure light is off but the car is jerking often while driving and also while shifting into gear. After spending several hours, worrying my transmission is busted and having autozone find the code, I figure out it was the sensor. So I plugged in the IAT sensor and disconnected the battery overnight, Next day I connected the battery and it started fine. My wife again drove the car about 12 miles that day. Then on friday night we drove to the grocery store and just as I was pulling into the parking spot, the car handled a little funny and the trac off light came on. I shut it off and started it again and the engine was vibrating. I shut it off and tried it again and it will vibrate more but wouldn't start. So I had it towed home.

Next day I check all the fuse, it is all fine. So I had a next door mechanic look at it. It was not starting and he bangs on the gas tank and it ran for a while, so he says it's the fuel pump.

Now all I want to do is make sure it is the fuel pump. I just don't want to change the fuel pump ( $ 400- $500) and find it's not the problem. Everything is fine with the car and everything is fine except it won't start. It will still start for a while if I hit the gas tank but not as long. Only my trac off light was on earlier but now my service engine light is on too. I don't think it is a passlock issue since the security light is not blinking. I already tried the fix for it anyway. I don't know if I even have passlock because my key is just a regular key although I have keyless entry. I just want to make sure it is the pump that needs replacement before and not go on a wild goose chase.

My one question is if the fuel pump is bad how can just hitting the tank make it work for a while.

I am sorry for such a long post but I just want to make everything clear. Although when it comes to alero problem, my story is always long. I spent all night yesterday looking at the various posts and I have had all the problem that I see here except that passlock issue. Thanks for all the help.