Where did you get the idea that you could install a Focus pump? I'm not sure that it will fit or that it will flow enough fuel.
Some here have posted that they have installed the SVT Focus pump only, not the whole pump module and in doing so that they had to make some modifications to the stock Contour pump module to make it fit. It is critical that it be the SVT Focus pump, not any other Focus pump.
On the issue of the ring in the bottom of the tank. First, a little history. As soon as the returnless system hit the streets, there were issues with the filter screen. Somewhere along the line some dealers noted that they were having repeat repairs from the scteen being plugged and some started unofficially removing the screen. Ford seemed to take no action. They introduced the the Focus with a similar pump design and continued to have problems and eventually initiated a recall for a new design pump. The new design required removing the locking ring from the bottom of the tank and the recall included providing the dealers with such a tool. Finally Ford realized that there may be something wrong with the Contour, Mystique, and Cougar design and issued a recall, but the recall did not go back far enough to include the Contours and Mystiques, only the newer Cougars.
Some have tried the newest Cougar pump module including making the modification to their tank and many have posted that they still have problems with fuel delivery.
I suspect that only the Focus SVT pump is strong enough to handle the V6, especially if it is an SVT. Again, the whole Focus SVT pump module may not fit. The only success that I have heard about has been to use the internal pump only and modify the Contour pump module to accept it.
I'm sure you can learn more detail than I have included in this post with a deeper search.
