Volguus

I know there's umpteen threads on this topic, and I've read as many as I could find, but the result (if any) of all of them, seems to be "live with it." With all the inventiveness and problem-solving in this forum, I can't believe that's as good as it gets. What good is stapling the latest HP geegaw onto your Stang if you can't even put gas in it without enduring snickers from pimply attendants and stinkeye from Large Marge behind you in her SUV waiting for you to finish dribbling it in?

This forum is full of veritable Sherlock Holmses, can't we pull ourselves away from the latest shiny things and focus on something pretty darn fundamental? I'll be happy to start (as if you couldn't guess).

If this fuel fill problem was a design flaw, why so many cases of "it was fine at first, then it got worse over time?" I'd think a design flaw would fail consistently, if not immediately. Nobody, me included, seemed to have this fill problem when the car was brand new, only later on. This speaks very clearly of something wearing out or otherwise deteriorating, as opposed to a bad design. True, the latter could cause the former, but that's beside the point for our purpose here.

I can speak only for myself, but my observations so far have been:

- As gas stations in my region modernized their pumps, my problem got worse.
- My tank filled perfectly only once in the last 3 years, at an ancient Serbia gas station (more on this later).
- I don't get a "FUEL CAP" error on my dash display (engine on) even when the cap is completely removed.
- I removed and checked the vapor filter apparatus behind the rear bumper; it was not noticeably clogged.
- Same goes for the fuel tank filler pipe. It is thin and tortuous, but only as much as it ever was. It, by the way, has no filter or valve devices inside it, it's a simple tube.
- I have NO errors or noticible behavior suggesting low gas supply to the engine, which rules out the fuel pump or emissions gear
- The "flapper" check valve in the gas tank inlet is spring loaded and appears to always seal the gas tank closed, not just when the car is rolled over.
- In my case, this valve required more force than I would have expected for a liquid to push it inward, and THAT's where I started to form my theory.

I think a combination of two factors are combining to cause this problem.

One thing I've noticed in the fuel coming from station pumps is that they have a LOT more air mixed into it than before. I imagine it's for vapor reduction, but that doesn't change the fact that what comes from the nozzle nowadays is more foam than liquid. And it takes a (relatively) long time for those bubbles to dissipate - up to a second or more. That's about twice as long as the fuel takes to get into your tank to begin with. I think the car's tank check valve is expecting the weight/pressure of a liquid to push it down and open. If it's getting foam instead, that may be too light/solid to overcome the spring threshold of the valve and that's why things back up. This theory is supported by 2 things: first, the aforementioned Serbia station pumped pure liquid gas, no air bubbles at all, and the car filled perfectly. Second, based on that I started using a large funnel (not a cone-shaped one, but like a large mug with the long flexible tube out the bottom) at my fillups. Theory being that the gas would have more time to dissipate its bubbles before going into the car, thus being more liquid and less foam. The locals laughed at the "rich American" having to play such games with his "fancy rich car," but the fact was - this worked.

Until recently. Now I'm getting overflow even with the funnel trick, and this leads to my second part of the theory: the spring on the car tank's check valve is getting firmer.

I have no way of confirming this because I don't know what it's supposed to feel like new, but on my 2006 GT, it strikes me as unnecessarily stiff. And other people on this forum have reported their fuel fill problem going away after some action that was speculated to defeat the tank valve. I don't know what causes a spring to lose it's springiness, but it's common enough. And the result may be that the tank fill tube doesn't get the access it needs, either in or out. This would also explain why the tank vacuum no longer extends up the filler tube to be affected by the fuel cap status. It would FURTHER explain why sometimes the problem was fixed by replacing the gas tank, even post-2005, and in some of THOSE cases, the problem returned. These are all accounts I have read in this very forum.

In retrospect, this would also even explain why turning gas station nozzles a certain way makes a difference. If the gas goes into the fill tube in a non-standard way, it may follow a longer, spiraling, etc. path along the inside surface of the pipe which may give time or help to dissipating the air bubbles in the gas.

So, in summary: I theorize that at least SOME S197 fuel problems are caused by a combination of more air in the gas supply and stiffening of the tank's checkvalve.

How does this sound to anyone who might actually know what they're talking about? :-)

- Ken -

flash_xx

Hmm, could be. Out here we don't have any of that fancy pollution control crap, just good old-fashioned gas pumps and my car has never had a problem filling up, but I thought the check valve was pushed open by the nozzle, not the liquid.

You could try a quick spray of penetrating oil (I don't think it would damage the engine considering you have to empty 1/2 can to take out the damned sparkplugs) and see if that fixes it. Or perhaps try a softer spring on the check valve.

bigray327

Seriously, turn the pump nozzle upside-down. You spent more time writing that novel of a post than you'd spend turning the nozzle for the entire lifetime of the car.

What's next, water on the floorboards?

bluovalguy

Let em talk about it. Maybe someone can come up with an decent idea that has not been tried yet. I dont have the option of turning it upside down cuz the hippie f$#*ing state I live in says an attendant has to pump your gas. By the time you explain to them what/why they are doing it you have wasted 5 minutes and gotten no gas. Then when they do turn it over, they rest the nozzle on my fuel door so they can fill up other cars.

So me personlly, I would LOVE to see a rememdy to this.

NOLA26

Dont know if they fixed the problem or not buy my 09 GT fules up just fine.

07 Stang

It does sound like an interesting theory, but for now, by just turning the nozzle 45° helps me.

DamnItzHenry

i had the problem before, but hasn't occurred for awhile now. Never did anything to the gas tank

Nuke

Even the "fix" per the TSB doesn't always work.

Some pumps are more prone to this than others so try to find a pump that doesn't give you this headache and stick with it. Otherwise, it's a combination of work-arounds.

• turn pump handle, sometimes 45*, sometimes 90* or more
• insert nozzle partially into filler neck
• begin pumping at slow rate then speed up to find where the pump kicks off, then backoff from where it kicked off
• stand on your head and sing your favorite song. spitting nickles may not hurt, either...

americaniron

http://ratstangrestoration.com/05_mustang_tank.htm I came upon this a while back, and saved it in case it ever happened to me. Give it a try and see if it works.

alkemist

I've never had a problem fueling as of yet and this was a pre-owned 2006. I pump at the same shell station 95% of the time and go to shell if I can. Possibly something with the quality of the gas or the pump.