2006 Liberty Sport 3.7 EVAP system nightmare. Seeking info, suggestions, help.

[JeepSpace]

Hello All,
I've had an ongoing issue with my EVAP system that no one can seem to pin down. I've worked with 3 mechanics, for various prices, expertise, and other reasons, and still no luck. Here's the History.

1. Noticed the vehicle would choke out and have trouble starting after driving a few hours and then stopping to fill up for gas. Vehicle would choke out while starting, but if I tried a 2nd time it would start. Soon after, it started with the Check Engine light and an EVAP code. Came back "Small Evap Leak" code.
2. Mechanic A suggests it could be Purge Solenoid, Evap Canister, or Gas Cap. Suggests I should start with the Cap as it's the cheapest test and fix. Replace OEM Cap from dealer. Problem persists.
3. Replaced Purge Solenoid by battery. Problem persists.
4. Reset Codes. Codes and check engine light come and go. See GASCAP light intermittently now comes and goes.
5. Mechanic B runs codes and gets "Large Evap Leak." Suggests it could be Evap Leak Detection Pump, Evap Canister, or leaks in lines, connections, hoses. Suggests doing Smoke Vapor Evap test first to check for leaks before buying more parts. He also suggested that if I cycled the key when I had trouble starting, to build pressure in pump/system, and then started, that it should help. This was confirmed. Every time I had trouble starting, if I cycled key once first, listened for gas pump to fire and build pressure in the system, and then tried to start it, it would start right up and not choke out.
6. Do Smoke Leak Test and physically inspect all outer components of system. Results find no leaks at all. Mechanic B suggests it could still be something internal to Leak Detection Pump or Evap Canister, and to start with the Pump since it is the cheaper fix. He also suggests it could be Gas Pump, but doesn't think that's the issue or I would be seeing other symptoms.
7. Mechanic A replaces Evap Leak Detection Pump. Problem persists. Mechanic A suggests that sometimes it's still a bad gas caps and to try another.
8. Replace Cap with an after market cap. Problem persists.
9. At this point, I'm still getting random Small Leak and Large Leak codes as well as the GASCAP code, and I am also smelling fumes every once and a while when I'm towing and accelerating hard to keep up speed while going up steep hills. The fumes usually go away after 15-30 minutes and or when the load calms down. Both the codes, check engine, GASCAP, and fumes all come and go. Sometimes it's a week or 2 with no issues or symptoms, and then they will just pop up again. Then it can go another week or so with no codes or issues; so very intermittent. The GASCAP light has become more regular, almost constant now.
10. Take it to Mechanic C to see what he can find. Mechanic C says it's likely the Evap Leak Detection Pump Filter, but that because I didn't replace the Pump and Filter at same time, that the new Pump could be ruined. Suggests I replace Filter and now Pump again, making sure to do the filter first. He also suggests it could be the Fuel Pump or the Gas Tank Sleeve, but that the sleeve should have showed up in the Smoke test.
11. Replace Evap Leak Detection Pump Filter and then the Pump again..... Problem persists.

So that's where I'm at. At this point the only thing I haven't replaced is the EVAP Canister. Any ideas what I should do next or where I should go from here?
Is the Canister the next best thing?
Could it be the pump, the gas sleeve, or something else?
I'm still intermittently throwing both Small and Large Evap Codes, as well as the GASCAP light is on almost all the time, but not quite all, and it still does respond to Cycling the key; that is if I cycle the key once, it never chokes out.
I've wasted so much time, energy, and money on this issue. I would have loved to find someone who knew how to fully diagnose the issue in the first place and hone in on the correct problem. In any case, I'm so appreciative of any help anyone has to offer, suggestions, or to steer me in the right direction. As well, I'm hoping this thread can serve to help anyone else with a similar issue.

 

[lfhoward]

Wish I could steer you in the right direction. When I had evap codes last time, it really was the gas cap. If you are not using Mopar parts, try that. Aftermarket stuff in my experience is hit or miss (usually miss).

 

[JeepSpace]

Thanks ifhoward. I have tried 2 new caps already, one Mopar OEM, the other after market. Neither seemed to change anything. The one mechanic had said it could still be the cap, that he's seen it where people have to go through a few of them before finding a good one, but when I mentioned that to the dealer, they said they had never seen or heard of that once in all their years, and that it was probably still something else such as possibly the fuel neck sleeve.

 

[Ksat]

What year lib do you have and what engine? A purge solenoid that sticks open can cause a vacuum leak, which can cause the hard starting issue you describe, including right after filling up. A pretty classic problem, actually. Checking the fuel trim % with a scan tool would be helpful in that regard, as high + values could point to that. It might help to look under your hood to see if there's a diagram of the system.

 

[JeepSpace]

What year lib do you have and what engine? A purge solenoid that sticks open can cause a vacuum leak, which can cause the hard starting issue you describe, including right after filling up. A pretty classic problem, actually. Checking the fuel trim % with a scan tool would be helpful in that regard, as high + values could point to that. It might help to look under your hood to see if there's a diagram of the system.

Thanks Ksat. It's a 2006 Sport, 3.7L. I did replace the purge solenoid as one of the first steps I tried, see steps 2 and 3 of description. Didn't make any difference.

 

[LibertyTC]

It can be difficult to locate Evap leaks. Find a shop that has a smoke machine, & hopefully a leak will present itself.
The gas filler neck can often be problematic.

 

[Johnny O]

Dollars to donuts its a bad canister.

 

[Ksat]

I did replace the purge solenoid as one of the first steps I tried,

Yea, I read that in your original post. Because it was replaced doesn't mean it's working correctly. It also doesn't mean it's being controlled properly by the PCM or their could be a wiring issue en route.

I would pull the solenoid and test it to see if it's working. It's normally in the closed position, so pressure should hold when it's power is disconnected. Connect a vacuum pump (or just suck on it) to both ports and see if pressure holds. Next, apply 12V to it, listen for a click and see if the pressure drops (allows flow between both ports).

If the valve is working, leave it out of the vehicle and plug up the purge line that goes into the engine intake. Start the car and see if it starts any easier. Again, it would be helpful if you could check fuel trim values on a scan tool prior to pulling the purge then again after u plugged up the line to see if there are any changes. Plugging up the that line should remove the entire EVAP system from the vehicle.

Find a shop that has a smoke machine,

He already had a shop do that and no leaks were found. I would suggest having another shop do a second test. The vent solenoid needs to be commanded closed by a scan tool or closed another way when performing the test. It is also important that the gas cap be left off at some point to make sure smoke escapes through the filler neck, as some vehicles have a fuel limiter vent valve, which would prevent smoke from traveling up to the filler neck area preventing a leak from being seen there.

Dyes can be added to smoke machine oils to make them more visible. Laser pointers can be helpful in being able to see smoke escape from a leaking area.

 

[69BahamaYellow]

These days, I can’t see escaping smoke from a small leak using a smoke machine So I just use pressurized air instead. Use a pressure regulator on your air line set to about 10 to 15 psi and you can hear the tiniest of leaks. I found a small leak on the gas tank to charcoal canister hose on a 2005 Liberty this way.

 

[JibeHo22]

I agree with 69Bahama - use air pressure as the diagnostic aid. But you will need good hearing and a quiet environment to hear the air leak. You can also use a soap water solution and a small brush to check the various fittings and joints along the lines. Bubbles will form if there is a leak.

 

[Ksat]

Compressed air can easily damage EVAP components and lines. Smoke machines only add 2 or so psi, which is somewhat difficult to achieve with your average compressor regulator.

 

[JeepSpace]

It can be difficult to locate Evap leaks. Find a shop that has a smoke machine, & hopefully a leak will present itself.
The gas filler neck can often be problematic.

Did the smoke test, Step 6 in op post, found nothing. Filler neck is still on the table though, but not the most likely according to mechanics.

 

[JeepSpace]

Dollars to donuts its a bad canister.

It is still my current most likely next part to suspect and to try and replace.

 

[JeepSpace]

Yea, I read that in your original post. Because it was replaced doesn't mean it's working correctly. It also doesn't mean it's being controlled properly by the PCM or their could be a wiring issue en route.

I would pull the solenoid and test it to see if it's working. It's normally in the closed position, so pressure should hold when it's power is disconnected. Connect a vacuum pump (or just suck on it) to both ports and see if pressure holds. Next, apply 12V to it, listen for a click and see if the pressure drops (allows flow between both ports).

If the valve is working, leave it out of the vehicle and plug up the purge line that goes into the engine intake. Start the car and see if it starts any easier. Again, it would be helpful if you could check fuel trim values on a scan tool prior to pulling the purge then again after u plugged up the line to see if there are any changes. Plugging up the that line should remove the entire EVAP system from the vehicle.



He already had a shop do that and no leaks were found. I would suggest having another shop do a second test. The vent solenoid needs to be commanded closed by a scan tool or closed another way when performing the test. It is also important that the gas cap be left off at some point to make sure smoke escapes through the filler neck, as some vehicles have a fuel limiter vent valve, which would prevent smoke from traveling up to the filler neck area preventing a leak from being seen there.

Dyes can be added to smoke machine oils to make them more visible. Laser pointers can be helpful in being able to see smoke escape from a leaking area.

Thanks, these are some excellent suggestions. I don't really have the ability or tools to do all the suggestions you make by myself at the moment, however it is great info I can try to pass on to the mechanics I'm working with. I did see something about sucking on the ports like you suggest in one of the YouTube videos I watched related to the issues. I'm also curious if the mechanic who did the smoke test did what you said with the gas cap. I'm guessing not, unless he was very familiar with such things. Not sure if I have the limiter vent valve or not. I do know though he said he did use dyed smoke and saw nothing. So far, I'm still inclined to try the Evap canister next, before a 2nd smoke test, since it's easier for me to do that versus finding someone competent enough or willing enough to do what you suggest, but after that I'd have to defer to what your saying, or anything else that others come with in the thread.

And whatever I do try, I will post the outcome to the thread. I can probably afford a canister in the next week, and get it installed in the next 7-14 days. Still I wanted to pick people's brains at this point before I even went through with that step. I also have this issue posted on 2 other forums, but still no replies there yet, but I will cross populate any info I get. Thanks again.

 

[JeepSpace]

These days, I can’t see escaping smoke from a small leak using a smoke machine So I just use pressurized air instead. Use a pressure regulator on your air line set to about 10 to 15 psi and you can hear the tiniest of leaks. I found a small leak on the gas tank to charcoal canister hose on a 2005 Liberty this way.

Will keep that option in mind for mechanic.

 

[Johnny O]

It is still my current most likely next part to suspect and to try and replace.

You got the fuel burp too?

 

[Michael Wolfe]

So, might I throw you in another direction?
Two things peak my interest. Smelling fuel vapor, and hard starting after fueling. The whole evap system uses vacuum from the engine's intake manifold, modulated through the purge valve. The system draws a slight vacuum on the fuel tank, filler neck, cap, etc. to make sure that there isn't a leak. Perhaps you're not getting enough vacuum. Have you tested the system "north" of the purge valve? ie. between the valve and the engine, and lines coming off the intake manifold?

 

[Ksat]

The whole evap system uses vacuum from the engine's intake manifold, modulated through the purge valve. The system draws a slight vacuum on the fuel tank, filler neck, cap, etc

I'm not sure it works that way on the lib as the OP said his mechanic replaced a leak detection pump. Detection pumps provide plenum (or positive air pressure) to the system- as opposed to engine vacuum as in your scenario.

A look on the bottom side of the hood might provide a diagram of the EVAP system and show the presence- or lack of- a pump. The service manual would also show it: http://www.colorado4wheel.com/manuals/Jeep/KJ/

 

[JeepSpace]

You got the fuel burp too?

What do you mean " fuel burp?"

 

[JeepSpace]

So, might I throw you in another direction?
Two things peak my interest. Smelling fuel vapor, and hard starting after fueling. The whole evap system uses vacuum from the engine's intake manifold, modulated through the purge valve. The system draws a slight vacuum on the fuel tank, filler neck, cap, etc. to make sure that there isn't a leak. Perhaps you're not getting enough vacuum. Have you tested the system "north" of the purge valve? ie. between the valve and the engine, and lines coming off the intake manifold?

Well the not enough vacuum is in line with what one of the mechanics told me, ie the one that said cycle the key to build pressure before starting. I personally haven't tested anything else then mentioned. I'm not afraid to tackle certain parts and repair, but I also have a limited tool set and live in a motel atm, so there's that. That is my options are limited for self work, and I can only afford repairs here and there in bits and pieces.

I did however, maybe have some new info today. I haven't smelled fumes in 2 weeks or so. I also have 2 gas caps to work with, try, or alternate. I had been using the aftermarket one, but it doesn't attach to my fuel lid that well, so I decided to revert to the other new OEM one I had gotten. Whereas over the last 2 weeks I hadn't received as many GASCAP warnings, all of a sudden the GASCAP warning was on almost all the time. I then switched back to the after market cap, and the warning was gone again. Oddly enough, the fumes happened using the aftermarket cap, but the GASCAP light was gone.

So either way, I 'm thinking my OEM cap has something wrong with it, yet I still think the problem is more than just the cap. I drove for 10 hours today, and the fumes happened twice. Both times was while revving hard to go up a hill while towing, and both times they lasted 10-30 minutes before going away after I got up the hills and leveled out again.

Would a bad EVAP canister allow a fume smell?