Long-term EVAP troubles

[Cobi Heckmann]

Hi all,

I've been an avid reader but wanted to become a participant of the discussion due to my troubles with the darn EVAP system. 2003 Liberty Sport 3.7L 4wd. Bought 2 years ago with the engine light on since.

I don't have a fancy scan tool (or the means to buy one right now) but I have replaced what seems like every piece of the EVAP system... LDP, nearly every hose/tube, purge valve, gas cap twice...

My only real symptoms are awful mpg (12-13 if I'm driving like grandma on the highway). Spark plugs are new, air cleaner and oil changes religiously, PCV new... I just need some pointers because I feel so lost.

Could there be a micro-crack in the top of the fuel tank sending guy?? Literally ANYTHING helps!!!

 

[tommudd]

Plugs, what brand and type ? NGK coppers hopefully

Most all Evap hoses I found with issues have been right around the rear diff / gas tank areas
Could be a cracked fitting even, very hard to see but it doesn't take much of a crack , have seen a few of them

 

[LibertyTC]

Be nice to know what the code number is: You can obtain code by using key trick.

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With a scan tool you can clear stored code to clear the engine light, or the other option to clear, is to disconnect both battery terminals for 20 min & then re-connect & see if light comes back.
Next would be a hard re-set where you would disconnect terminals, clamp them together for 20 min.

 

[LibertyTC]

Often the best & easiest way to find EVAP leaks is by finding a shop with a smoke machine.

 

[adamkrz]

I had the same issue ( small evap leak ) chased it with parts for about a year , finally dropped the fuel tank and found very small cracks in the top plastic bushing that sits on the fuel tank, up to 2004 they used a 2 piece fuel pump assembly that is no longer available - ordered a used fuel pump assembly and 1 more for a spare and problem was finally solved..

A smoke test did not find this leak.

 

[Shankster]

Hi all,

I've been an avid reader but wanted to become a participant of the discussion due to my troubles with the darn EVAP system. 2003 Liberty Sport 3.7L 4wd. Bought 2 years ago with the engine light on since.

I don't have a fancy scan tool (or the means to buy one right now) but I have replaced what seems like every piece of the EVAP system... LDP, nearly every hose/tube, purge valve, gas cap twice...

My only real symptoms are awful mpg (12-13 if I'm driving like grandma on the highway). Spark plugs are new, air cleaner and oil changes religiously, PCV new... I just need some pointers because I feel so lost.

Could there be a micro-crack in the top of the fuel tank sending guy?? Literally ANYTHING helps!!!

I've replaced a bunch of cracked evap hoses above the rear axle (Autozone had fuel hose by the foot that worked perfectly) and seemed to solve my constantly cycling evap solenoid cycling issue (at least it's quieter now). Sounds like you've been there done all that too though.

In regard to scan tools - 2 suggestions - Autozone (I don't work for them, honest!) will run a scan for free. Also, I bought a clone USB ELM327 connector ($7) and ScanMaster Pro ($10) off eBay and run them off my old Windows 7 laptop - really slick, I now have scanning capabilities way beyond what I could ever need. I didn't ask if the software was pirated but I think I know the answer!!

 

[tommudd]

Key trick is how I get all of my codes when working a KJs
no computers needed or wanted

 

[Cobi Heckmann]

Plugs, what brand and type ? NGK coppers hopefully

Most all Evap hoses I found with issues have been right around the rear diff / gas tank areas
Could be a cracked fitting even, very hard to see but it doesn't take much of a crack , have seen a few of them

Yep, NGK coppers! Thanks Tom!

I had the same issue ( small evap leak ) chased it with parts for about a year , finally dropped the fuel tank and found very small cracks in the top plastic bushing that sits on the fuel tank, up to 2004 they used a 2 piece fuel pump assembly that is no longer available - ordered a used fuel pump assembly and 1 more for a spare and problem was finally solved..

A smoke test did not find this leak.

I'm thinking that might be my next step... thanks for the great info! Where can I get a pump assembly? A scrap yard and hope it works??


Any thoughts on using an appropriate epoxy on that plastic?

 

[runfor5]

Hi Cobi - Like you I've gotten help on here over the years and try to give some back now. We have a 2004 Liberty KJ Sport trim w/ towing package (tow hitch + trans oil cooler from the factory). I chased a P0456 code for a few years before caving on the $300 to have a smoke test done (I can be a cheap bastard lol) - cost was also high because it took them 2 hours to find. As you mentioned off the bat, a micro-crack on the top of the 2-piece fuel pump assembly was my issue.

See the picture with the bubble in the divet part of the top of the assembly? The dirty/messy dark photo. That's my leak via the smoke test. Had the shop plastic solder it right then and (knock on wood) been fine since summer 2019.

I have admittedly have that code pop-up randomly again, but its always been the gas cap.

I have attached pictures (hopefully they load...let me know if they do not) of when I dropped the fuel tank for a fuel pump replacement. Having done so multiple times now, crappy pumps lol, its super easy. 4 bolts attach the black metal straps that hold the tank to the frame. Lower it on your chest and slide on out. I've done it without the car jacked up.

 

[runfor5]

Sorry, just to add more. As @adamkrz said that entire "upper" 2-piece fuel pump assembly is no longer made by Chrysler nor aftermarket. I presume due to the fuel tank explosion risk they're trying to get the cars off the road. Nonetheless, a junkyard is your only option if that ever goes bad. Same for all those connectors/lines sitting atop the fuel tank.

Again for me thankfully, the plastic soldering has worked. Note the "upper" assembly is SEPARATE from the fuel pump part that actually sits inside the bottom of the fuel tank - that's still readily available. See 2 pics attached here for the different parts I'm talking about (the yellow one is the "upper"/"top" part no longer made).

Also in case your curious, a 2004 has a different upper fuel assembly from a 2003 lol. I got a super clean upper assembly out of the yard, went to put it on, and the lines shot right off when starting the car! So back to the trusty soldered one I went. Compare img_0966 (2003 version) to that per my photo img_0960 in prior reply.

 

[adamkrz]

Sorry, just to add more. As @adamkrz said that entire "upper" 2-piece fuel pump assembly is no longer made by Chrysler nor aftermarket. I presume due to the fuel tank explosion risk they're trying to get the cars off the road. Nonetheless, a junkyard is your only option if that ever goes bad. Same for all those connectors/lines sitting atop the fuel tank.

Again for me thankfully, the plastic soldering has worked. Note the "upper" assembly is SEPARATE from the fuel pump part that actually sits inside the bottom of the fuel tank - that's still readily available. See 2 pics attached here for the different parts I'm talking about (the yellow one is the "upper"/"top" part no longer made).

Also in case your curious, a 2004 has a different upper fuel assembly from a 2003 lol. I got a super clean upper assembly out of the yard, went to put it on, and the lines shot right off when starting the car! So back to the trusty soldered one I went. Compare img_0966 (2003 version) to that per my photo img_0960 in prior reply.

Great write up and photos, Plastic solder and epoxy both a option -I was lucky to find 2 entire fuel pump assembly's in great shape -my next option was to maybe retrofit a newer kj fuel tank w/ the standard one piece fuel pump.

 

[JeepLibertyKK]

Chasing down Check Engine Light or EVAP issues can be rough. I experienced one on my 2012 Liberty (KK). Turned out to be cracked line in the engine compartment. I checked them but never would have found it without help. It was on the backside of a 90 degree bend along the firewall on the drivers’ side.