2000 cadillac deville has been sitting in backyard for 2 years. Recently diagnosed with low pressure on fuel pump. After i replace fuel pump, how likely is it that the gas lines have been corroded...an old school mechanic said he wouldnt do the work due to potential complications from clogged lines, etc. Is there anything that you recommend that I could do to increase the chances of having an operable vehicle after I get the pump replaced?