I have a 99 Lumina, 3.1, that has ongoing shutoff problems. So far I have replaced the ignition module, 3 coil packs, Crank Position Sensor, Knock Sensor, as well as a burnt through wire from the CPS on the back of the engine. All seemed to be going well, till the temperature warmed up here in NC, and now it is back to its same old crap. Does not matter how fast you are going, or if you are sitting still.....it just shuts off like it runs out of gas. I have noticed that the fuel pump has gotten noisy, it whines and you can hear it inside the car. Any suggestions would be greatly appreciated.

Sounds like you may have answered your own question...borrow a fuel pressure gauge and see what happens when it stalls...

Of course the Sevice Advisor at the dealership where my wife works cannot possible accept the fact that since everything else has been done, and it does not throw an error code, that it might be the fuel pump, so I will see what he decides to do today to fix this problem.

An intermittent fuel pump problem rarely trips any code. Occasionally, it will throw codes involving lean/rich fuel due to the fluctuating volume of fuel, but not very often. A fuel pressure test would finger it.

I would deffinitely run the fuel pressure test first, and a little trick if it is intermittent is hook the gauge up (if you don't have one beg,borrow or BUY...lol)and run it up over the wiper cowl and tape it to the base of the windshield, so you can keep an eye on it when you are driving. If it is the fuel pump, the pressure will drop off when it dies. I will say though that this problem (when associated with heat like you said) is usually an injector shorting out. I'd run a resistance check on the injectors and see if one of them has fallen below 12 Ohms.

The mechanic took the car home with him last evening, with a fuel pressure gauge taped to the windshild as you suggested, so I will find out today I hope if it showed anything. One other thing that I should perhaps mention here, this car has done this occasionaly since it was purchased brand new by my wife's sister, but when taken to the garage, you cannot get it to do it while they drive it. Very random, and at times after shutting off and giving you fits for several hours, it will run just fine for 2 or 3 months.

Well, the never ending saga continues.....2 days at the dealership....2 days of them driving it in the heat....with a fuel gauge on it.....and about all they can say is they do not THINK it is the fuel pump, because it has the proper pressure....of course they have not been able to get it to shut off either, so who knows. I gave them the message in regards to checking the ohm's to the injectors....but of course they ruled that out without bothering, since that definetely was not the problem. Anybody else have any suggestions ??? I am getting ready to sell the thing if I cannot get it fixed.

After having the technician drive the car in the heat for 3 days, it finally shut off on him in traffic, with the fuel pressure guage taped to the window as suggested. After installing a new fuel pump, all seems to be well, and the car seems to be running better than ever. Hopefully this problem at long last has been solved.

Yeah..I hope so too...I hate seeing those intermittent things that I can't get to happen...you'd be surprised how often I hear "it was doing it all the way here!" LOL...hope you got it fixed.