Hi all, I'm new here. I have an 03 Dakota Sport quad cap 4x4 4.7L. I have 228000 miles on it and it still runs great. Recently I threw a code which said "small evap leak", I don't remember the code. I took it to a dealership and they did a smoke test and didn't find anything. I've changed the gas cap. The light is still on and the truck idles kind of rough. Any thoughts?

Thanks in advance,

Chris

 

I've battled the same problem. Think I have it licked now but I've thought that before. Right now I show zero codes.

Replaced with new OEM gas cap and checked hoses underneath truck for cracks, etc. It didn't help. I also have records showing that previous owner had smoke test done. Guess it didn't work very well so I have little faith in smoke tests.

It wasn't until I pulled the battery and tray that I found a few cracked hoses connected to the leak detection pump. Standing in front of the truck it sits just right of the battery.




Here is a view of the hoses with the battery tray removed. You have to remove the tray to get to the hoses that come up from underneath. The pump is sitting upside down, still connected



I cut the cracked ends off, reconnected, then zip tied. I also found a split hose up next to the brake master cylinder. Look closely and you'll see the split between my fingers. The screwdriver points to where the hose came from.







Cleared codes and weeks later it returned. Guess it was still cycling. Cleared again and have been good ever since. That's about two months now. Fingers still crossed.



If it's not the hoses... you can probably try changing the LDP or the canister which sits underneath near gas tank.

PS, doubt it would be the cause of your truck running rough.

 

I didn't want to tell you this but Dodgevity spilled the beans you need to do the same as Dodgevity.


A long search to find the leak

 

Thanks for the info guys. I guess I have some more detective work to do!
have a good one,

Chris

 

At our age/mileages, it's expected for some hoses to start cracking here and there. The evap is one of the most sensitive systems to that issue. As you can see, my battery tray was quite nasty so It was a good opportunity to throw it into a bucket and wash it down real good. I also hit the area with some baking soda and water. Looks like new now.

 

Yeah, that's my next project to take the battery and tray out and inspect the hoses down there. It makes sense that the smoke test failed. If the crack is down there, it may have been hidden.

 

I would just start replacing all your vacuum lines with new silicon vacuum lines all your old hoses are going by now.

If you can find the silicone hoses locally great but the silicone hoses can be hard to find.

Here is a good ebay place for the hoses by the foot LINK

I like the silicone hoses as they stretch very well to varying size metric and standard USA connections and are strong

 

sounds like a good idea. Also, would a bad PCV valve cause this?