Emmisions Vapor Leak - JeepForum.com
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post #1 of 5 Old 07-10-2021, 06:34 AM Thread Starter
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Emmisions Vapor Leak

I have the check engine light and check gas cap light. I have already replaced almost everything on the emissions vapor recovery system. New Fuel Tank, fuel neck, gas cap, vapor canister, purge valve, integrity valve on canister, lines. Checked, doubled checked, and triple checked the rollover valve on the fuel tank where many have broken before. I have put a vacuum on the system and it holds for a while. I have smoked the system and have not found any leaks. Cleared the small leak fault several times. I am running out of ideas. Has anyone ever actually had a problem in the ECM? Any help or ideas are greatly appreciated.

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post #2 of 5 Old 07-10-2021, 10:25 AM
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2014 JK Wrangler 
Join Date: Oct 2017
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what year, post ALL codes and did you look for TSB's?

It may be necessary to command the EVAP to on to check system for leaks when you smoke it.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 5 Old 07-10-2021, 02:07 PM Thread Starter
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Year: 2007 Jeep Wrangler JK X.

Only Code is P0456 - Small EVAP Leak
Passes large leak test when performed.

When I smoked the system I unhooked line from purge valve and blew smoke back to fuel tank. Had smoke coming out of the vent (attached to the fuel neck) which I believe is the last part of the system. I then unhooked the line going to the vent from the integrity valve and plugged so that I was not loosing smoke out the vent. After doing so I did not find any leaks anywhere. When I took the fuel cap off lots of smoke came out so I think I had good smoke through the system. After not finding any smoke I hooked up a manual vacuum pump up to the same point with the vent still plugged and was able to hold a vacuum on the system. I believe at this point the only thing not in the system being tested would be the purge valve and line going from purge valve to intake. I have replaced the purge valve twice so I don't think that is the problem. With the engine running you can feel a pretty good vacuum coming from the purge valve from time to time when holding your finger over the line.

I briefly looked through the TSB's and did not find anything on the EVAP system.
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post #4 of 5 Old 07-22-2021, 06:19 PM
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Did you use an oem mopar gas cap or cheapo from auto parts store? Actually makes a difference alot of times

1997 XJ 6.5 mixed RC,OME,IRO w/ SYE.
2001 XJ 4.5 RC lift,JK Wheels w 32's
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post #5 of 5 Old 08-05-2021, 05:02 PM
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2012 JK Wrangler 
Join Date: Apr 2014
Location: Freeport
Posts: 252
I've been chasing the same code and have had no luck so far!
Asked a shop if they would smoke test it and the owner said, "If its running good forget about it, it's just a Jeep!
Fat chance I'll ever let him touch my Jeep!
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No matter where you go, there you are!
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emmision , leak detection pump , vapor

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