Earlier today I was looking up how to clean the MAP sensor becuase I have a p0238, and stumbled across this http://www.dodgeram.org/tech/dsl/ISB/low_power.htm
So when I was out inspecting the MAP and discovering that I don't have a big/deep enough socket to take it out I decided to check my tank vent. To my suprise I discovered a black plug where there should be none, I double checked that it was the tank vent that sometimes has the red plug left on, I came back and looked it up to make sure I was right. So I took some pictures and then removed it, took it for a test spin to warm up the engine. After parking I opened the fuel tank and no more hissing air. Just wanted to share what I found and confirm that it was a good Idea to remove the little cap.

 

That's an odd one? I've never seen one that style, just the smaller red/black ones that slid over the nipple.

 

I agree, I've only seen the red ones. I definitely don't think it belongs there though.

 

I was pretty surprised when I saw it, i had to come back and dig up more info for about an hour before I went and messed with it.

 

so, is the vent line left open to the atmosphere? any possibility of running some line up a ways to get to cleaner air (or put a small filter on the end of it?

 

When looking up information about the cap I read a little bit about a vent mod where a hose is connected to the vent and ran up into the frame, whith a filter placed at the open end. I might do that over winter or thanksgiving break. There are also two other vents located at either end of the tank which are supposed to be plugged from the factory, but supposedly some aren't and can lead to water and dirt in the tank, so I am going to check all that stuff soon, ULSD already has me worried enough