Hello Members: 1990 D250 318 TBI Automatic. I dropped the fuel tank to change the pump. The metal lines were all rusty and fell apart and the vacuum lines also fell apart which is ok because I will replace it all anyhow. Question is, the vent valve has 2 nipples on it. A smaller one and a larger one. I can tell where the smaller line hooks up and goes but cannot tell where and what kind of line hooks to the bigger nipple because it all fell apart. The underhood vacuum diagram shows the smaller line comes up to the canister purge solenoid but just shows the bigger line goes to the fuel tank which makes no sense. Found the answer, those hood diagrams are not very easy to follow. the big nipple is apparently the atmosphere vent and only the small nipple is connected to the canister. Thanks