I have a 1997 F-250 diesel. Recently I've noticed a small stain where I park. I opened the hood and discovered that the leak is on top of the engine. I found a small amount of diesel fuel pooled on the intake manifold. I also found what appears to be a vacuum hose that was not connected. Apparently the clamp broke and the hose came off. I know where the hose was connected but I'm not sure what the unit is called on top of the engine. I had to remove the 7.3L plackard and the unit it right behind it. It has a small yellow toggle on the lower front left corner that says open and closed on it; What is this unit? I cleaned up the pooled fuel and I've been driving for a couple of days. The leak seems to have slowed; I only saw one very small spot yesterday when I checked my parking place. Can anyone offer any insights? Is that unit a fule pump or some sort of vacuum controller?

 

That valve is your fuel drain from the fuel filter. You really shoul dbe draining it a bit every month to keep water from collecting in the bottom of the filter housing. Just move it to the open position for a few seconds then close it.

Not sure what the hose is that you are talking about. The one to the map sensor above the air conditioning box blows off sometimes. Not sure.

If that fuel drain is leaking first make sure it is closed all the way. It may need an oring kit put on it. It's a cheap and relatively easy fix.