Seat Ibiza 1.4 gasoline year 96, starts and stops

Hello, if someone can give me a hand. My problem is that I have a Seat Ibiza 1.4 gasoline from the year 96, the car starts perfect but the second stops. As much as I try always does the same. I have changed the air filter but it is still the same. What can you do?
Thanks in advance

Hi Madmax, well with what you say because there is not much, but well. If I don't remember that engine badly, it was a monopunto injection. You should start looking at the easiest, if the gasoline pump works correctly, if the right tension comes, if you do not noise the pump when operating, etc. If everything is correctly, then see if it is the problem of the gasoline filter, which unfortunately, gasoline filters are usually the great forgotten. Try to change it.
If after all this it remains the same, because the complications begin, because you do not comment if it is cold, which I suppose if you say you can not start it, or if it gets to start and hard start a few seconds or directly sticks the time trying to start. I think you commented that it started and stopped immediately, if so, the same thing happens that the opening times of the injector are very long and ends up drowning the engine, or that the slowdown regulator is not working properly, what I do not remember is if this model carried a regulator that acted by pushing the gase butterfly or was an engine of steps.
To check the injection times you have no choice but to do it with an oscilloscope, but it is almost more likely to the idle regulator, which is dirty or defective, try to see and you will say.

Buy a spray to clean carbureting acceleration bodies and clean yours is possibly full of because it forms over time you throw it accelerate to the maximum (sienpreter the car off) and clean it with a trapa and a rod on the sides until it is clean, and check the temperature sensor and if you do not check the pump relay and then make the other story.

Thanks for your help.
But consult the problem with a SEAT mechanic and told me that if it started well and the second one stopped, as was my case, it had to be of a immobilizer that wears, that surely the key of the car had distrusted and you have to configure it in the workshop, to try with the other key that it had to start. Well, nothing tries with the other key and starts perfectly. I did not know that such an old car has the key electronically encoded.
Well, nothing said, thank you very much for the help.

If you want to cleanse the chapter of the acceleration body that it is over and so you also achieve a regular minimum