Problem with my focus !!!

HELLO EVERYONE!!! I wanted to ask you if you can help me:
I have a Ford Focus Model 2000 Zetec 2.0 16V engine, approximately 10 days ago I burn the gasoline pump replaced it with an original pump. After this I find that having a fourth fuel tank or less, sometimes the atina vehicle to stop (begins to fail) with an apparent lack of fuel. I stop the engine and start it again and the car begins to walk well. This action followed it for a few days after changing the pump, until I bought another bomb again and changed it again and the problem follows. I have changed 2 new bombs and continuously with the same inconvenience.
Please someone who can give me an idea !!

Well, first of all pump is not the problem is that the pump must be outside its base that is located inside the tank if the pump or the complete cojunct is not subject to the base that is in the anchor of the tank the pump will fail.

The companion's response is correct since your bomb must be out of its base, nothing more would be a thing to review that little detail..OK

Friends that give it for granted is already reviewed, the bomb has only one correct position and a specific fitting, that is why having changed everything I cannot find where the failure is. I thank you for your time and if you know from any other option I will accept it. Thank you all

I think you must check if you have changed the fuel output and arrival tubes. If these are well the fault you have in the aeration of the tank, apart from the fact that you must also check the fuel filter.