Evap system leak

[jesseshoots]

FWIW, just because a fuel cap passes the test at the local emissions station doesn't mean it wont throw a CEL. When I was designing the fuel cap for the Rugged Ridge Elite line, I kept throwing CEL's after 50 miles even though the cap was passing the emissions test. We had to switch from a nitrile to viton gasket to fix the issue. We were basing the cap around the inner components of the MotoRad cap.

This is the same cap that is run on '01 and newer Wranglers.

 

[KCsTJ]

On our jeeps there are a few common areas for leaks, the flexible line between the engine vacuum manifold and the hard line on the frame, this line is located on the frame under the drivers side foot well. Follow the line from the purge valve toward the tank and you will find it. Another place is the line and connections above the tank that go toward the canister, and the large lines on the canister itself. Also the service port, the Schrader valve can leak.

That's good info, im getting an annoying code 441, generic purge valve issue. Time to check fittings and places u mentioned

 

[C.J. Roberts]

I had multiple small and large evap codes for a year and a half before I finally got it fixed. I replaced the gas cap, purge valve, Leak Detection Pump and all the rubber hoses and fittings. Smoke showed a crack in the gas tank, so that was replaced. Then it had a crack in the fuel filler tube. Replacing that solved the problem... for a while.
When it came back, smoking the system didn't show anything. Finally my mechanic figured out the the schrader valve that you plug the smoke into was leaking, so it was removed.
The last time it happened, smoke didn't show anything, but my mechanic took some emery cloth to the gas filler where the gas cap went, roughing the surface creating a good seal, FINALLY fixing the damn thing.

 

[Rollin20z]

Also make sure to check metal line running from hose connection from tank running inside drivers side frame rail up to under drivers floorboard in engine compartment where it returns back to rubber hose coming up to evap on drivers inner fender well. I found some corrosion on mine where it goes up over rear axle and down in and around rear control arm bracket when I pulled tank to change out skid plate. I cut it out and put a piece of 3/16" brake line with a couple pieces of 3/16" vac hose as connectors and ordered some new 3/16" rolled brake line to run entire new 1 piece front to back. Very cheap and easy to do. IF you need it, or just want to refresh those lines. Figure 20yrs under there in the elements will take it's toll on those as it does everything else under a Jeep. And brake line is right there with it so while your at it. You know how that goes.

I actually ended up with a 4 pk of tubing(like 100' for $24) way too much but never hurts to have extra. But here's enough for $10 to do front to back new and fittings thrown in.

https://rover.ebay.com/rover/1/711-...0001&campid=5337789113&icep_item=291697244318
Also just used a simple cheap spring bender and with this line being easily bendable I had no problems putting it where it needed to be.

A set like this, even though I have a regular tubing bender these worked much easier as I started at front and just let the spring ride back the line bending it where needed. Just remember to pre route your tubing over tranny skid plate,rear axle and around thru any brackets first. Then go back with bender and straighten and tighten,bend as needed to fit into frame clips already there holding old line. Pop out old pop in new.

https://rover.ebay.com/rover/1/711-...0001&campid=5337789113&icep_item=183781927938
Anyhow just throwing that out there for anyone who may not have thought about that line and are only looking for racked rubber hose connections leaking throwing codes.

 

[KCsTJ]

And this will show leaks for the evaporative system?

Yes, it will. If you have a leak that is. The smoke takes all the guesswork out of the process and shows you exactly where the problem is

 

[KCsTJ]

Also make sure to check metal line running from hose connection from tank running inside drivers side frame rail up to under drivers floorboard in engine compartment where it returns back to rubber hose coming up to evap on drivers inner fender well. I found some corrosion on mine where it goes up over rear axle and down in and around rear control arm bracket when I pulled tank to change out skid plate. I cut it out and put a piece of 3/16" brake line with a couple pieces of 3/16" vac hose as connectors and ordered some new 3/16" rolled brake line to run entire new 1 piece front to back. Very cheap and easy to do. IF you need it, or just want to refresh those lines. Figure 20yrs under there in the elements will take it's toll on those as it does everything else under a Jeep. And brake line is right there with it so while your at it. You know how that goes.

I actually ended up with a 4 pk of tubing(like 100' for $24) way too much but never hurts to have extra. But here's enough for $10 to do front to back new and fittings thrown in.

https://rover.ebay.com/rover/1/711-...0001&campid=5337789113&icep_item=291697244318
Also just used a simple cheap spring bender and with this line being easily bendable I had no problems putting it where it needed to be.

A set like this, even though I have a regular tubing bender these worked much easier as I started at front and just let the spring ride back the line bending it where needed. Just remember to pre route your tubing over tranny skid plate,rear axle and around thru any brackets first. Then go back with bender and straighten and tighten,bend as needed to fit into frame clips already there holding old line. Pop out old pop in new.

https://rover.ebay.com/rover/1/711-...0001&campid=5337789113&icep_item=183781927938
Anyhow just throwing that out there for anyone who may not have thought about that line and are only looking for racked rubber hose connections leaking throwing codes.

Excellent post, thank you!

 

[Claude]

Jumping in here-- we've got a 2004 TJ that keeps throwing EVAP codes. Smoke tested it at an offroad specialty shop multiple times, and nothing — no leaks found. Gas cap is clean and testing fine.

Any ideas?

Check the locking ring that holds your fuel pump tight and airtight in your tank.
Mine wasn't..it was loose..
Tightened it and I finally cured my 2001 Evap codes.

 

[Claude]

See