This is a strange one. I am considering buying this 1995 6.5TD truck, but I am having trouble diagnosing a problem. It starts and runs fine for about 200 miles, then it starts to smoke profusely. Get out, pop the hood, and open the bleed vent on top of the fuel filter to let a bunch of air out, then the smoke goes away and is fine again for 200 miles or so. The lift pump was replaced, and it is working due to fuel coming out of the filter bleed. Will air in the filter cause the smoking? Any ideas on the cause? Please help. Thank you. Adam