Wrangler TJ Gas Overflow Fix

MountaineerTom said:
Are you talking about changing the filler hose to the GM filler hose, with the little flapper in it?

Thats what these guys are referring to about fixing the problem, not the symptom. With the GM hose, it will still do the same thing, but hopefully the little metal flapper in the hose will stop it from burping out. I’ve read some posts where the GM hose doesn’t stop it from burping out all the time. If you remove the tank and pull the plunger thing and do what the video says, you will fix it and not need the GM hose.

I may have missed it, but what year is your Jeep?
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Thank you. I have an 05 Rubicon, and yes, I meant the GM hose. I‘m not at all interested in band-aid fixes - I read this thread months ago and it sounded like the GM hose was a solution (has a valve that doesn’t get stuck with ethanol use) so I put it on my Amazon Wish List and haven’t really paid much attention to the thread since then. Since I decided to drop the tank this weekend I went ahead and ordered the GM hose.

I don’t meant to kick a dead horse here, just want to understand. My issue is that when I fill up, the pump doesn’t seem to know my tank is full in time and it overflows (unless I slow down to a trickle.) Gas doesn’t come out after I’ve stopped pumping, it never shuts off before full, and gas goes in as fast as the pump can deliver it. My understanding from reading this thread months ago was that there‘s a valve in the tank, and a valve in the filler hose. I thought (from this thread) that a stuck filler valve meant the pump doesn’t shut off in time, and a stuck tank valve meant slow filling and/or fuel spilling after the pump stopped. It seemed to me like there were 2 separate problems being discussed.

Again, I just want to understand so I can learn and fix it properly. How do fuel pumps know when the tank is full? Is there even a valve in the OEM filler hose?
 
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Aloha Joe said:
Thank you. I‘m not at all interested in band-aid fixes, I just hadn’t re-visited this thread in a long time. I have a 2005 Rubicon. And yes I meant the GM hose. I read this thread months ago and thought the GM hose was the ‘solution’ so I put it on my Amazon Wish List and haven’t really paid much attention to the thread since then. Since I decided to drop the tank this weekend I went ahead and ordered the GM hose.

I don’t meant to kick a dead horse here, just want to understand. My issue is that when I fill up, the pump doesn’t seem to know my tank is full in time and it overflows (unless I slow down to a trickle.) Gas doesn’t come out after I’ve stopped pumping, it never shuts off before full, and gas goes in as fast as the pump can deliver it. My understanding (from reading this thread months ago) was that there‘s a valve in the tank, and a valve in the filler hose. I thought (from this thread) that a stuck filler valve meant the pump doesn’t shut off in time, and a stuck tank valve meant slow filling and/or fuel spilling after the pump stopped.

Again, I just want to understand so I can learn and fix it properly. How do fuel pumps know when the tank is full? Is there even a valve in the OEM filler hose?
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There was no valve in my OEM filler hose for my 2005 unlimited Rubicon. I did the GM hose Band-Aid fix last year and the problem still persisted with slow fills sometimes and burping gas over spills at other times. I bought a genright tank and installed it a few months ago and haven't had an issue with it because it has a different rollover valve. With my OEM tank sitting in my garage, I decided to pull the rollover valve and sand the nubs down on it so it doesn't stick for the next person that gets my OEM tank. Whether you have slow pump or gas spill over issues depends on which position the rollover valve is stuck. Removing the roll over valve, sanding the Nubs down, and reinstalling it should solve your issues
 
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I just watched a video the other day on this because I get a little burp at the end most of the time. I naively thought this was the problem everyone was talking about and I just slowed my roll at the end of the fill up and that solves the burping issue. However the video showed what the problem actually is; if the "shut-off" valve down in the tank is stuck in the up position it closes down the valve's opening into the tank so very little gas can get through. If it's stuck in the down position it allows gas to flow in as normal but then it doesn't pop up so that the fuel nozzle doesn't know when to shut off. If it's stuck up you'd absolutely have to fix it and I can't see where the GM hose would make any difference at all. Mine is apparently stuck down so I would imagine I'm overfilling my tank every time. That's my uneducated take anyway.
 
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KillerIsMe said:
I just watched a video the other day on this because I get a little burp at the end most of the time. I naively thought this was the problem everyone was talking about and I just slowed my roll at the end of the fill up and that solves the burping issue. However the video showed what the problem actually is; if the "shut-off" valve down in the tank is stuck in the up position it closes down the valve's opening into the tank so very little gas can get through. If it's stuck in the down position it allows gas to flow in as normal but then it doesn't pop up so that the fuel nozzle doesn't know when to shut off. If it's stuck up you'd absolutely have to fix it and I can't see where the GM hose would make any difference at all. Mine is apparently stuck down so I would imagine I'm overfilling my tank every time. That's my uneducated take anyway.
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We should clarify something... the gas station fuel filler nozzle will shut off automatically based on pretty old technology that uses the principle of the venturi effect to sense when the fuel is reaching (or has reached) the tip of the nozzle. This technology has nothing to do with the make/model/age of the vehicle; the type of hose; whether that hose has a flapper valve; whether the fuel tank has a roll-over shutoff valve; etc. If fuel gets up to that point, the nozzle will automatically shut off.

What we have happening in our TJ's is that the fuel flow INTO the tank is constricted because of the roll-over valve being stuck in a closed (or semi-closed) position down at the bottom of the fuel inlet (not the rubber filler hose itself). Since flow into the tank is restricted, gas keeps backing up inside the filler hose, triggering that venturi effect and telling the fuel pump to shut off.

~john
 
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John Young said:
We should clarify something... the gas station fuel filler nozzle will shut off automatically based on pretty old technology that uses the principle of the venturi effect to sense when the fuel is reaching (or has reached) the tip of the nozzle. This technology has nothing to do with the make/model/age of the vehicle; the type of hose; whether that hose has a flapper valve; whether the fuel tank has a roll-over shutoff valve; etc. If fuel gets up to that point, the nozzle will automatically shut off.

What we have happening in our TJ's is that the fuel flow INTO the tank is constricted because of the roll-over valve being stuck in a closed (or semi-closed) position down at the bottom of the fuel inlet (not the rubber filler hose itself). Since flow into the tank is restricted, gas keeps backing up inside the filler hose, triggering that venturi effect and telling the fuel pump to shut off.

~john
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I think there are actually at least 2 problems being discussed in this thread:
1) is what you just described
2) is everything filling up as normal, but the gas station nozzle failing to recognize a full tank in time before gas spills out. Flow into my TJ's tank is unrestricted and will take fuel as fast as the pump delivers it. But once fuel reaches the filler hose, it's a split second before gas comes gushing out around the nozzle. I'm thinking, if it really has to do with the gas tank valve, that a normal working valve closes but still lets some fuel through, so when it closes fuel fills up the filler tube but at a slower rate than if the tank were full and overflowing into the filler tube. This is based on my experience that, at full flow, my tank completely fills up and overflows before the nozzle shuts off, but if I reduce flow at the last minute, the nozzle is able to sense a full tank. This same situation has also been discussed in this thread, and I think in this situation the added GM valve is probably more effective.
 
Aloha Joe said:
I think there are actually at least 2 problems being discussed in this thread:
1) is what you just described
2) is everything filling up as normal, but the gas station nozzle failing to recognize a full tank in time before gas spills out. Flow into my TJ's tank is unrestricted and will take fuel as fast as the pump delivers it. But once fuel reaches the filler hose, it's a split second before gas comes gushing out around the nozzle. I'm thinking, if it really has to do with the gas tank valve, that a normal working valve closes but still lets some fuel through, so when it closes fuel fills up the filler tube but at a slower rate than if the tank were full and overflowing into the filler tube. This is based on my experience that, at full flow, my tank completely fills up and overflows before the nozzle shuts off, but if I reduce flow at the last minute, the nozzle is able to sense a full tank. This same situation has also been discussed in this thread, and I think in this situation the added GM valve is probably more effective.
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Yes. Your valve can be stuck in any position along its path. If it's at the up side it will restrict the flow into the tank. If it's at the down side it won't pop up and trigger the pump to shut off so the pump shuts off when the gas flows all the way up the line to where the nozzle is. That's the burp. That's how I understand it.
 
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Chris said:
The actual fix is is to drop the tank, sand the nubs on the plastic piece in the overflow valve , reassemble the valve then raise the tank back in place. The only "part" required is a piece of sandpaper as shown in the video below.
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I guess when I drop the tank to install the Savvy skid plate I'm going to also need sandpaper.
 
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BuildBreakRepeat said:
Is there a longer than stock hose that can be substituted to accommodate a BL? Not to fix the discussed issue.
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Possibly. I've done many body lifts. All of the filler neck hoses have been able to be used by simply loosening the clamps and working the hose off the neck a bit. In general though, we don't have to do anything because we are raising the body 1.25" and raising the gas tank 1" with the Savvy skid.

Even before that though with other combinations, we never had to do anything but loosen the clamps, work the hose out a small bit on the filler neck ends and they worked fine.
 
BuildBreakRepeat said:
I dislike only having 1” of bite on the tank fitting. If there is a hose like OEM but slightly longer I’ll take it. If not I’ll live with it :)
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1" of bite is more than ample. Anything other than the amount that it takes to get the clamp on is excess to stop your feelings from being hurt. You want the clamp just a bit past the end of the hose so it can't scoot off. Then you want the clamp below the bead on the neck. After that, not much else matters.
 
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mrblaine said:
1" of bite is more than ample. Anything other than the amount that it takes to get the clamp on is excess to stop your feelings from being hurt. You want the clamp just a bit past the end of the hose so it can't scoot off. Then you want the clamp below the bead on the neck. After that, not much else matters.
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Depends on how far down the hose the bead of the neck is. I prefer the clamp maybe 4" down from the end of the hose so it's firmly on there. It's okay when it scoots off once in a while but when the tank is about ready to be full I like that clamp to stay put. Your mileage may vary though.
 
mrblaine said:
Possibly. I've done many body lifts. All of the filler neck hoses have been able to be used by simply loosening the clamps and working the hose off the neck a bit. In general though, we don't have to do anything because we are raising the body 1.25" and raising the gas tank 1" with the Savvy skid.

Even before that though with other combinations, we never had to do anything but loosen the clamps, work the hose out a small bit on the filler neck ends and they worked fine.
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All the more reason for savvy’s GTS earlier than later. Thank you for your clear and concise response.
 
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