The tank vent is a little cone shaped thing attached to the bottom of the fuel tank. I jack my car up, put it on jack stands, put boards under the tires (safety first) and use my creeper to get to it. I replaced it a long time ago when I thought it was not working. I tested it after removal and it was fine. Turns out the woosh of air that I was hearing when I uncapped the fuel tank was air coming out. Never did figure it out. Oh well. That was like 175,000 miles ago.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900