I've been putting this one off for a while since it wasn't causing any issues at the time but my MPG has decreased now (assuming this is the reason for the decreased MPG). So revisiting this issue. I took the truck to a mechanic today and they did a smoke test and found NO EVAP LEAKS whatsoever. They seem to think the CEL code was just some kind of fluke and won't come back after they reset it. I'm not convinced because I've reset the computer several times and it always comes back after about 60-80 miles.

Most people commenting on various threads regarding this issue said they found a cracked hose or some sort of leak. Anyone found a different cause to this problem besides an EVAP leak?

 

I found a partially clogged air intake on the NVLD pump on my 2005, but I do not think this is the same system as yours.

 

I'm glad yours was that simple. From all the forums i've read online, it sounds like the system is similar on most Chrysler vehicles made around 2003-08 and possibly more years so I doubt yours is different than mine but i'm not sure.

I've seen many posts that said they had to replace the NVLD pump. Assuming it doesn't rain this weekend, i'll see if I can get under there and check mine for clogs and such. I might even just replace it if I can find one. You wouldn't happen to know the part number of that NVLD pump, would you? Or where I can buy one? I searched O'reilly AutoZone Advance Auto and Mopar's websites and can't find the part number.

Found this one on Amazon but the part number doesn't return a result on Mopar's website.
http://www.amazon.com/Chrysler-Detec.../dp/B0074JC8B4

 

Smoke tests are very unreliable when it comes to pinholes and dry rot. Fuel systems are like coolant systems in that the hoses rot from the inside out. Moving or squeezing these hoses can crack the inside of the hose while leaving the outside looking perfect. When visually checking your system, pay close attention to mounting/clamping areas and where lines slide onto nipples. If the outside of the hose has the slightest rot or cracking, guaranteed the inside is shot. I had a very good mechanic tell me to come back in 6-8 months to redo smoke test in order for the leak to get large enough for smoke test to be effective. He was correct.

 

If someone has a scan tool with the ability to a run a forced monitor test on the EVAP system, it's a real game changer. Internal leaks cannot be detected by a smoke test (unless there is a vacuum diaphragm on the EGR or the like) and the internal pressure tests aren't really that reliable. There are times when there is no substitute other than to swap a purge valve or an ESIM switch. ESIM switches are total garbage and very cheap. Something new they have integrated now is a fuel tank pressure sensor. By watching the data during a monitor test, you can usually detect any internal leak. I have had 100% predictability so far with it. At least when the pressure sensor isn't full of raw gas where someone has done the fill up click-o-rama

 

I'm not sure waiting longer will do me much good at this point because I've had this issue for at least a year now. The leak might be getting worse or something is changing over time because now I can only drive 10-15 miles after resetting the computer before the CEL comes back on. In the past it was over 100 miles then about 50 miles, now 10-15. Seems like it should be bad enough now for the smoke test to find a leak. My MPG has also dropped to about 15 when it used to be 18-20.

My scan tool definitely can't do that; it's just a cheap one that reads codes. The mechanics I've been to didn't mention anything about that either. I'm not familiar with this pressure sensor you mention but I'm wondering if it could be filled with fuel like you said. I don't do the "click-o-rama" when I fill up but there was one time that the gas pump failed to shut off and I had gas pouring out of the side of the truck until I stopped it.

 

2007 didn't have the pressure sensor. I was rambling on, sry. The rest applies though.

 

I attempted to look at the NVLD pump this weekend. I can see it from the rear drivers side wheel-well but I can't reach it to check anything. I think I would have to drop the fuel tank or take the bed off neither of which I want to do. I do need this fixed and I've already been to a couple mechanics so I think I will be taking it to a dealership next.

 

The instructions in the owners manual apply only to the std. Dakota cab. If you have a quad cab, you will have to drop the fuel tank and skid plate if you have one. First, check the inlet hose for the NVLD pump to see if it is clogged. It plugs into the left frame rail forward of the fuel tank. Disconnect the other end of the hose from the NVLD pump. Because the hose plugs into the frame rail, it is prone to get sand, etc. into it if used under dirty conditions. Try to pour/shake out any foreign particles from the frame end of the hose (you can try blowing through that end toward the pump end to determine if the hose is clogged (do this with the hose removed from the vehicle). If clogged. blow through the other direction and shake out as much dirt foreign matter as possible. Once you can blow through the hose, you are good to go. I removed replaced \every component of the NVLD system (except for the fuel tank) before I found this problem. This entailed removing the fuel tank five (5) times. Be careful that you do not break the plastic fuel inlets on the pump. Rock Auto has all of the parts for the NVLD system, or they did when I was working on mine. Yes, it is a very simple solution if that is the problem, but very time consuming and expensive to find. Needless to say, this cause/solution is mentioned nowhere in the service manual. Good luck.