6.5 GM motor fuel supply

I have a safiri motor home has a 6.5 turbo motor. I bought it it set 9 years. I started it drove it 90 miles home. It started acting like it was taking on to much fuel. I checked the return line. Nothing coming out I replaces all the fuel filters the lines both to pump & return. Replaced fuel. At start idle runs good up to 8-10 hundred RPM then puts out white smoke over black. Fuel runs off the exhost pipe & now its hard to start. Then on the return nothing coming out it. Its got a 4 way T or side ways H for the return. We did pull a injector line & she run good but started dying like starving for fuel. I know its in thereturn some where what can I do I ever tried blowing out the new lines this has only 25000 miles not over that Iv been showed papers but also set between 9 & 10 years & yes I changed the fuel please someone help me if I get good I give my word I will donate thank you Kevin