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2003 GC 4.0L Evap Code and Hard start after filling gas

Discussion in 'Performance & Tuning' started by SpartanRouge, Oct 26, 2018.

  1. Oct 26, 2018 at 12:03 PM
    #1
    SpartanRouge

    SpartanRouge [OP] Member

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    Aaron
    Vehicle:
    2003 Grand Cherokee Larado I6 4.0 2WD
    I Have been battling an "Evap Large Leak Detected" code for some time now.. when i first got the truck it would come back more or less 2 days after clearing. I smoke tested it and could not find any leaks besides very small one coming from a vent outlet, which i am told is supposed to be there. Then i started to experience the engine starting hard and running strange only for a minute after filling the gas tank. Thought that might be the pressure regulator so i changed that then a weird noise was happening when i cycled the key so i figured the new regulator was making the fuel pump work harder than it was used to so i changed the pump. still had the noise and turned out it was a bad new regulator! BUT the evap code didnt come back for a few months after i dropped the tank and changed the pump. now it is back and still starting hard after tank filling. I even tested the purge valve with a scan tool and it seems to be working well but i decided to swap it out with a different one (not new) and same thing happens. what should i blame next?? Evap pump that runs the test? Canister? I feel like its causing bad gas mileage too because it has a brand new engine and it only gets about 9-13mpg round town.
     
  2. Oct 26, 2018 at 12:34 PM
    #2
    Prerunner1982

    Prerunner1982 Well-Known Member

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    Wow Aaron, I wish I had an answer for you. That does seem like some below normal MPGs.

    Here is something I found online, hopefully it may help you.

    Grand Cherokee P0455 Trouble Code Causes
    There are many things that can cause the P0455 trouble code to trigger in your Jeep Grand Cherokee. Here are the most common problems that will throw the code:



    • Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. This will cause the P0455 code. Look for either a tear or hole in it. This is one of the most common issues that causes the code
    • Vapor Canister Purge Valve– One of the most common causes of the P0455 code is the vapor canister purge valve. It’s really easy to replace. There are a few clips that you need to find and remove.
    • Faulty Charcoal Canister– The charcoal canister is often the cause of P0455.
    • Fuel Tank Sending Unit– It is possible for the gasket that attaches the fuel sending unit to the gas tank to go bad. This can reduce tank pressure and throw the code.
    • Fuel Cap– A bad fuel cap can cause the code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. If you are getting that message, plus a P0455, it may save you a ton of time and money to replace the fuel cap and see if it goes away.
    • Fuel Filler Neck– There is often a gasket where the fuel filler neck connects with the gas tank. This gasket can dry out, especially with vehicles that spend their time in dry climates. When it dries out, the fuel tank can’t hold pressure anymore.
     
    JKBob 25 likes this.
  3. Oct 26, 2018 at 1:57 PM
    #3
    Awrench

    Awrench Well-Known Member

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    POST all the codes.

    When you refuel do NOT top off tank, when pump kicks off you are done...
     
    JKBob 25 likes this.
  4. Oct 26, 2018 at 7:29 PM
    #4
    SpartanRouge

    SpartanRouge [OP] Member

    Joined:
    Oct 6, 2017
    Member:
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    21
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    Male
    First Name:
    Aaron
    Vehicle:
    2003 Grand Cherokee Larado I6 4.0 2WD
    Ill have to wait till it comes back to be 100% of the code number but I'm pretty sure it is the P0455 that prerunner posted about and it is the ONLY code that gets thrown. Very rarely do I overfill the gas tank. I set the pump up to run and stop when it kicks off so i know I'm not causing it by over filling.

    I think i need to start looking at the canister and its vent valves or even the pump that runs the evap leak test. I hear it beeping for like 4 minutes sometimes when i do a cold start in the morning and ive never heard of any other car beeping like that. I was even able to force it to run the leak test with my scan tool. i could hear it beeping from the left side of the rear bumper cover.

    Prerunner1982 the "Vapor Canister Purge Valve" that you speak of, is that the solenoid under the hood near the air filter box on the left side? or is it a different one on or near the canister? And like I said, I have smoke tested the system a few times and I'm fairly certain it is not ACTUALLY leaking from any dry rot hoses or gaskets.
     
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