DiscoV8i

Hi. I´me adressing you from Portugal, hope to exchange some ideas with you all. Meantime, would apreciate some opinions from you. Have a Discovey 3.5V8i with autobox, and a RPI engines kit. The problem is that the fuel pump keeps failing all the time, have exchanged it several times and the problem goes on. Is this normal in these engines? What can I do to find/fix the problem? Would apreciate very much your opinions on this. Cheers