HOW TO: fix the KJ fuel burp plague!

Discussion in 'How To' started by ol-flattop, Nov 28, 2014.

  1. ol-flattop

    ol-flattop Full Access Member

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    Yesterday evening, fueled by turkey, taters, cranberry sauce, and delicious homemade pies of every sort, I finally tackled the fuel burp issue that has plagued my KJ since I bought it. One Liberty write-up has been done, but it was pretty abstract and didn't get much attention. So, since there’s been some renewed interest in this topic and there's still a void to be filled, here is a thorough set of instructions. With the benefit of hindsight, I’m putting them in a different order from the way I did it. It took me quite a while to get done, mostly because I kept trying to save time by leaving the jeep together as much as possible. That turned out to be pretty dumb, and I’ll try to save you the time and hassle.

    For background info, there’s a problem with some KJ’s, shared by some JK’s, where you can’t let a fuel pump keep going all the way to auto-shutoff without fuel spurting back out at you. Some people, for no apparent reason, continue to deny that this problem exists because their particular KJ doesn’t experience it. Others confuse it with another problem that manifests itself in the opposite way (i.e. the auto-shutoff is actuated when the tank is nowhere near full), or else they assume that it can only occur when users try to ‘top off’ the tank by adding more fuel after the auto-shutoff has already been activated. Here’s a youtube vid showing this particular problem.

    (In the interest of full disclosure, this paragraph is just my understanding of the problem based on web research. It’s not the authoritative source, just the best explanation I’ve seen, in the absence of costly scientific testing.) The problem is apparently caused by the fuel tank rollover valve, which has the dual purpose of preventing fuel from pouring out of your tank if you, well, roll over, but also of preventing fuel from belching back out of the tank when you fill it. This valve, at least on some KJ’s, includes a rubber gasket which in theory should make it super-duper effective. But when it comes in contact with ethanol, the rubber expands, binding the valve and preventing it from closing. So, you end up with a nice smelly burp of gasoline at the end of each fill-up, unless you approach the mundane task of pumping gas with the same care a skilled neurosurgeon employs in digging around someone’s brain. No fun. Jeep has quietly ignored the issue, apparently to avoid admitting they made yet another mistake. I’m told they will fix it, if asked to, by replacing the entire gas tank, since the rollover valve is integral to it. I presume the new tank will have a different gasket that handles ethanol better, but (shockingly) it’s tough finding people willing to foot an $800+ bill just because of the fuel burp issue, so there’s not much info to go on.

    For some reason, not all KJ’s are plagued by this problem, and it doesn’t seem to be a large proportion that has the issue. Since ethanol supplementation has become pretty much pandemic and thus can’t be the determining variable, my speculation is that the rubber gasket on the fuel tank rollover valve is only present on models with the California emissions package. I’m hoping for some feedback from those who experience this problem—do your Jeeps have this package, as mine does? You’ll have to check your build sheet or engine bay to find out for sure. Of course, one or two who have the fuel burp issue but not the CA emissions package would blow my theory out of the water, but if so please share! I’m interested in finding out the truth, not being proven right.

    Whatever the reason, our Jeeps are barfing out gasoline like a baby gorged on mama’s milk. You can only find it cute for so long, and then it needs to stop! To that end, let’s get started!

    1. Get GM part 15131046HOSE (I used ebay, shop around and you'll find a good price), and cut out the flapper valve from the center using a razor utility knife. Be careful not to damage the valve. Or yourself. While you’re at it, you might as well salvage the hose clamp on the end—just snip that claw off. I used it later, in step 13.[​IMG]
    2. Get some plastic pop rivets. My searching of LOST, Jeepforum, and KJ country turned up Napa part # BK 7702871 for this, but they weren’t a perfect match. Close enough for jazz, though. Here’s the Napa rivet next to a removed Jeep rivet.[​IMG]
    Contrast that to one of the Harbor Freight rivets that came with the rivet tool (coming up in step 3!), which is a nearly perfect match. Emphasis on ‘nearly,’ there, for reasons to be seen later.[​IMG]
    3. Get a riveter. You’d think a regular one would work just fine, but the two I tried didn’t have a collet large enough to fit the Napa rivets. There was one just large enough for the HF rivets, but I couldn’t get it to release the waste portion of the mandrel. This one from Harbor Freight worked like a charm, and cost 16 bucks. As a bonus, it happened to come with an assortment of rivet sizes, one of which, mentioned above, is almost identical to the Jeep rivets. If you’re on a really tight budget, you can get the rivets alone for 6 bucks or so and make them work using two pairs of pliers, some patience, and probably a list of expletives, but there’s a reason they make a tool specifically for this job.[​IMG]

    For most, those are the only two/three purchases you’ll have to make for this job. I got the GM hose for $25, and the HF tool and rivet assortment for $16, for a grand total of $41 (+tax) invested in this fix.

    4. Jack up the rear driver’s side, stick a stand under the axle, and remove the wheel. You could probably get the job done without this, but it takes two minutes and makes everything that follows much easier.
    5. Remove the four rivets visible below from the rear fender flare. You don’t need to touch the one on the bottom at the rear (out of view), or the ones on the front panel of the fender flare, just these four.[​IMG]
    I did this using a variety of tools and methods, but the most effective is to use an appropriately sized drift punch (yeah, all I had on hand was a small screwdriver, which works but isn’t ideal) and hammer to drive the mandrel in, collapsing the rivet on the other side. Once it’s loose, you can use a claw hammer, pry bar, or sometimes just your fingers to pull the whole rivet out.[​IMG]
    6. Next, remove the three plastic push-rivets that secure the wheelhouse liner to the wheelhouse behind it. I was able to get a small prybar behind the liner in all three spots to remove the rivets without ruining them, but there are also tools made specifically for this task, which will make it a tad easier.[​IMG]
    7. Pop out the wheelhouse liner. Toward the front of the jeep, the liner just meets the fender flare with very little overlap and no attachment except the push rivet you just removed. Start there, then pull the center down and toward you, and finally the whole thing will pop out nicely.[​IMG]
    Now you have easy access to everything you need.[​IMG]

    If you really wanted to, you could probably get the job done without accessing the fuel hose from the wheelhouse as described above. But it would be a royal pain in the butt. Unless you really can’t afford to replace a few pop rivets, this is the best way to do the job.
     
    Last edited: Nov 28, 2014
  2. ol-flattop

    ol-flattop Full Access Member

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    Part 2

    8. Now that you have access from the wheelhouse side, you need to get access to the hose’s connection to the fuel tank. If you have a fuel tank skid plate, you’ll have to remove it. This is the first time I’ve been glad my KJ has no skids.[​IMG]
    9. With your access portal opened up, you can attack that hose clamp. In my case, it was seized pretty badly, and I almost wrecked it before addressing the issue. A quick spray of WD-40 fixed that problem nicely, and the clamp loosened right up. You could use a flathead screwdriver, but a 9/32 socket works a whole lot better.
    10. Pull the hose off the fuel tank. This was surprisingly difficult on my Jeep. YMMV, but I had to work at it quite a bit to get it to cooperate. The cold contributed, I’m sure, and vacuum pressure might have added to the difficulty before I removed the gas cap, but mostly it was just a hose that had made its home and didn’t want to leave. Eventually it came off the fuel tank mouth. Then pull it through its hole in the frame as well, and you’ve got a nice open area to work on it. [​IMG]
    If you skipped steps 4-7, then instead you have a tiny, cramped area and are lying on your back with a flashlight in your mouth and a sore neck. Yup, hindsight is 20/20.
    11. You might be able to get the other end of the hose off the filler tube, but I wasn’t, and it really isn’t necessary or particularly helpful.[​IMG]
    At this point, I marked the top of the tube as a reference for correctly timing my flapper valve. While eyeballing it will probably be just fine, a little extra help can’t hurt.[​IMG]
    12. Now comes the fun part. Make CERTAIN you have the valve positioned to open toward the tank! otherwise, you’ll be unable to fill the tank, and will have to start all over. And you’d feel really dumb doing that, wouldn’t you? Orient the valve with the hinge pin on top so that gravity keeps it shut when held level, and then stuff it up the hose. Others have suggested using a deep well socket the same diameter as the valve housing to drive it in. I didn’t have one that size or close enough on hand, so I ended up using a 6” socket extension. Worked like a charm.[​IMG]
    I just alternated pressing the valve housing at the top and bottom until I got it past the bend in the hose, which is as far as it’s really necessary to go. Use whatever works for you, but that’s how I did it. You’ll want to be careful of a couple things: first, if you use something smaller than the valve housing, you risk the tool slipping off and smashing the flapper valve or its hinge pin. If that happens, it’s game over. Second, if you use something the same size or larger than the valve housing, that means it’s also larger than the hose, and you risk getting it irretrievably stuck in the hose behind the valve! Pick the risk you’d rather manage, then don’t screw up![​IMG]
    13. This is probably unnecessary, given the interference fit between valve and hose, but the name of the game here is overkill. Take the hose clamp you salvaged from the GM hose at the beginning, and install it around the valve in the hose. Here you can see the valve’s profile in the hose.[​IMG]
    And now, with the clamp installed.[​IMG]
    When you look up the hose, you should now see this. [​IMG]
    If so, you’re practically done!
    14. Thread the hose, with newly installed flapper valve, back through the hole in the frame and onto the fuel tank mouth. Tighten the hose clamp, nice and tight. Don’t just snug it on there, keep going or this connection WILL leak, and paying for fuel as it drips directly onto the ground is kind of what we’re trying to avoid, right? The wrench will tell you when to stop—you’ll notice a SHARP increase in resistance, and then it’s perfect.
    [​IMG]
    15. Replace the wheelhouse liner. Now you get to use your snazzy new riveter. It’s really easy, and pretty much self-explanatory. One note, however: remember I said the HF rivets were nearly perfect? I stuck in a couple of those rivets with no issues, then had several in a row where the mandrel popped off before the rivet compressed. [​IMG]
    Sure, I remember NOW that I’d read that could happen, and to soak them in water beforehand to avoid that problem. At any rate, when I ran out, I just used some of the bigger ones, and everything’s cool.
    16. Replace the wheel, drop the Jeep from its stand, dutifully torque those lug nuts (80-100 ft-lbs, if memory serves), and you’re all done. Yes, I know that my wheels look like crap and that my tires actually are crap. One catastrophe at a time![​IMG]

    So that’s how I spent my Thanksgiving night. After a year of living in fear of a nasty fuel belch on me or another unsuspecting driver of my jeep, I’d finally done something about it, and was left with a feeling of deep satisfaction. The only thing that could have made it more satisfying would be if the fix had actually worked!































    I’m kidding. It worked like a dream. No more spit up. I guess my baby’s growing up. :happy107: Enjoy, folks!
     
  3. TwoBobsKJ

    TwoBobsKJ Full Access Member

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    Very good writeup! I don't have the burp problem (at least on my KJ... :emotions34: ) but I'm sure this will really help those who've been dealing with it for a while.

    Your pics have reminded me to look behind the fender liners for rust and deal with it before winter REALLY sets in :waytogo:

    Bob
     
  4. profdlp

    profdlp Grouchy Old Cuss

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    If I still have the Jeep come next Spring I intend to do this. Thanks for a great write-up! :D
     
  5. MarkJ

    MarkJ Full Access Member

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    Outstanding pictures!
     
  6. uss2defiant

    uss2defiant Full Access Member

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    This better be a sticky!
     
  7. 4x4kayak2112

    4x4kayak2112 Full Access Member

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    Holy crap rust.....
     
  8. ol-flattop

    ol-flattop Full Access Member

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    Not sure how to read 'at least on my KJ...' Does another of your vehicles have the issue? If so, the principle of this fix might very well be applicable there, too. The GM hose was, after all, created as a retrofit to solve this same problem on some GM vehicles.
    Oh, it's just a little character :icon_lol:
    I do need to work on that, but as I said in the write-up, one catastrophe at a time!
     
  9. 4x4kayak2112

    4x4kayak2112 Full Access Member

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    So this does NOT fix the clicker stopping the nozzle when its not even full?
     
  10. ivantate

    ivantate Full Access Member

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    Thanks for the detail. Might give this a go at some point. Problem is i will also see some rust and either havr to do something about it or moan about for a few weeks after.
     
  11. ol-flattop

    ol-flattop Full Access Member

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    It does not. This fix is for those of us with the exact opposite problem:icon_lol:

    Your question opens up an interesting topic, though. When I first came across the explanation about the rubber gasket and ethanol, I noticed that some people were interpreting it as the gasket temporarily expanding immediately following contact with ethanol, and others as permanently expanding and binding the valve forever. Anecdotal evidence doesn't clearly support or refute either possibility. If it's a permanent thing, and the valve is getting bound up for good in a partially closed position on some KJ's, then your problem might be the same thing, just manifested in a different way - i.e. the partially closed valve restricts the flow of fuel into the tank, so that it backs up in the filler tube and actuates the auto-shutoff.

    I know that the rollover valve is located in the gas tank itself, but I'm not sure whether it's at all reachable from the outside, with or without detaching the tank from the jeep. Unless someone else around here who does know chimes in, you might have to do an exploratory on your tank to diagnose the problem. If your rollover valve is bound in a partially closed position, you might be able to manually shift farther open, at which point you'd want to install the GM flapper valve, or you'd just be exchanging your current problem for my past problem. And I can tell you that my infant son is far less irritating when he takes a lot of unnecessary breaks during a meal, than when he guzzles it down without interruption, then pukes all over me.:happy175: I guess we have to take what we can get!
     
  12. ace400xs

    ace400xs New Member

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    I have the fuel burp problem on my 06 Liberty. It is not the CA version.

    Thanks for posting this information. I will have to look into trying this fix.

    J
     
  13. nohitter64

    nohitter64 Full Access Member

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    Eureka! Thanks ol-flattop for posting this. This has been an annoying problem on my '06 for the three+ years that I have owned it! This will be next on my list.
     
  14. ol-flattop

    ol-flattop Full Access Member

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    Thanks for the info. I'll have to go back and edit that part out sometime.

    Of course, that opens up the question again: why does this only seem to afflict a small minority of KJ's? If anyone has ideas, I'm all ears.
     
  15. dude1116

    dude1116 Full Access Member

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    Doesn't seem to be a small minority. Seems to be many. My Jeep doesn't burp up...however you can't even top it off $0.40 otherwise it will overflow. Not sure what that's about but I bet it's related.
     
  16. ol-flattop

    ol-flattop Full Access Member

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    I agree many KJ's have the problem - but there were almost 900,000 sold in the US alone, and even on this forum we seem to be a minority. Consider that owners of so-afflicted KJ's are far more likely to chime in with their experienes than are those whose KJ's don't burp, and it's tough to conclude that this problem is common to anywhere near half of the KJ's on the road.

    Alternatively, I suppose it's possible that most people with this issue just don't give a crap about spurting gasoline all over themselves, but I find that dubious for a number of reasons. :icon_lol:
     
    Last edited: Jan 6, 2015
  17. Birdman330

    Birdman330 Full Access Member

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    I used to have the burp problem as well when I first bought the KJ, but after a year of not running Ethanol but pure 87 Octane fuel having brought up it seems the issue is related to ethanol blended fuel, the burp problem has gone away. If the problem returns I know how to take care of it now!
     
  18. ol-flattop

    ol-flattop Full Access Member

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    Great to know! That points toward the temporary gasket expansion theory, I'd say. I hope we can get more user experiences and establish the answer for good!
     
  19. CactusJacked

    CactusJacked Full Access Member

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    Chrysler issued a TSB on this issue. 2005-2009 KJ's are affected, as well as a number of additional Chrysler makes. Their claim, based on tests, is that the poppet (seal part) of the check valve will swell too far if subjected to fuel that exceeds 10% ethanol. With E10, the clearances tightened up and were close: .91mm (35 thousandths). That didn't bind the valve up, but doesn't leave a lot of wiggle room should the seal want to swell just a tad more. Not to mention, Chrysler's soak test wasn't performed over a number of years, as the valves in the vehicle's tanks have been subjected to. Here's the TSB: Fuel Nozzle Service Bulletin
     
  20. 4x4kayak2112

    4x4kayak2112 Full Access Member

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    Hmmm interesting the 2005-2008 is affected. My 06 keeps tripping before full. Sometimes i have to slowly fill it.