I replaced the thermocouple in my gas furnace and it is running longer than it did before but it still shut off so what is the problem?

It could be a couple of things:

1. Wha is the condition of the pilot light? Does it have a yellow or white color to it? If so it will need to be cleaned. It could also be buring with to much pressure and blowing itself out.

2. What is the thermocouple connected to? If it is a silver color box (and not directly the gas valve) it could be weak and need repllacing.

3. If it is connected to the gas valve, that could be your problem as well, but it is an expensive replacment item.

4. Is there a down draft coming from the chimney? Air blowing down the chimney that does not have a cap on it can also cause the pilot to blow out.