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Fuel filler Mods

"PJ Moran" said:
Point is, I think the flap would cut down on splash against the actual cap, cutting down on any leakage that may be occuring.
good point
I think the flap should be incorporated if feasible.
I'll see what I can do but it will make it much more complicated. I'll wait for warmer weather too to go junk yard hunting...
 
"PJ Moran" said:
I have a pop-open gas cap. I think they're the bee's knees, but I've never been sure about how well they seal. The new ones use a regular cap inside and the pop-open part is purely cosmetic.

Point is, I think the flap would cut down on splash against the actual cap, cutting down on any leakage that may be occuring. I think the flap should be incorporated if feasible.

I wonder if it would be easier to attach a flapper valve at the bottom of the filler neck, ie, a flapper the full diameter of the filler neck, that would minimize fuel coming up the filler neck to begin with. It could be set partially open for venting. I mean, we're talking about large volume gasoline gushing up the filler tube, right, so anything to block the wave would work, and then the piece near the top of the tube should further keep anything that gets past from coming up.

I thought maybe some more plates welded in lower in the tube, with the holes drilled off-set to each other to create a series of baffles, but the holes would still need to be large enough to let full stream gasoline from the pump get past without backing up.

Another option is a second plate with a larger hole and flapper valve could be tacked into place from the bottom of the tube.

No hard feelings if any or all of these are disregarded. I know what its like to be working on a project and have the "good idea fairy" visit a ton of people who want to help out, especially when you are near the end and just about have it all figured out.
 
the biggest issue with flappers or baffles like you mension would be if it restricts filling flow. The nozzle is designed to auto shut-off if flow backs up. Baffles and flaps could cause the nozzle to keep shutting off. From reading the patents and design stuff the flap's main purpose was just that, to restrict flow so leaded fuel could not be pumped into an unleaded fuel car. PJ's suggestion of using one would help splash on the pop-open cap's seal when driving but does nothing for filling issues. Since I don't have an elaborate shop I am trying to keep it simple to make as well for reliability too. Aside from PJ's concern I think the one I just made for Pete will work good. My car has a repop pop open cap and I chose not to install the spring and seal and use a twist on gas cap so I don't have any issues with leaks when driving. It does help to have a few guys out there to give feedback under different conditions. We'll see what Pete says after he uses it, but I do appreciate the ideas. Keeps me thinking. So far a few guys on the Fix have some of the ones I've made now so that's kinda how I arrived where I'm at with it. When the gallery is up again I'll post some pics of Pete's that I made yesterday.
 
"tarafied1" said:
My car has a repop pop open cap and I chose not to install the spring and seal and use a twist on gas cap so I don't have any issues with leaks when driving.

Does the cap you use vent? If not, how do you handle normal venting (ie, when not filling)?
 
A gas fairy makes sure the tank is always full of gas, regardless of how much (or little) you've driven.
 
well if it's a fairy it could just magically appear in the tank!


Here is Pete's, first pic from inlet side with drain hole at bottom. 2nd pic is tank side and you can barely see the deflector that should prevent fuel from going back thru the drain hole. Last pic is the side view, you'll notice it's quite a bit different than a 67/68 shape which is pretty much an elbow.
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Last edited by a moderator:
Got it tonight. Will install as soon as this rain passes which should be sometime Fri, Sat for sure.
 
No problem. If anything happens to quick in the Mustang world, one begins to wonder......
 
Finally got around to installing the modified filler neck. Naturally, it went in with no problems.

Then, today I went to fill the car to see how it functioned. After checking the fit of the nozzle, I felt it might not work. It seemed that the modification kept the nozzle about 1-1.5 inches further out of the neck than I liked. In the past, the nozzle fit up to the rubber splash guard. So, I placed a towel below the neck to catch anything that might happen. I then pumped some gas slow. All looked well. Then, I went to full flow.....I put in 10 gallons like that. The auto shut off worked as it should and the amount is real close to what I figured I needed since my gauge is screwed. Upon shut off, I removed the nozzle and saw a bit of dampness about 1" down the neck and the fuel nozzle had dampness to match that position. No fuel escaped the neck at all.

On the way to the RV, I did a couple hard accelerations and then checked the inside of the cap for dampness. I could see dampness in the neck but no fuel seemed to reach the cap as it was still dry. Any fuel that got past the modification had drained back down thru the small drain hole.

All in all, I would say it works good. I will continue to monitor it and report if there are any problems.

Thanks tarafied1...............
 
Pete:
We'll need to check the anti-siphoning capability the next time you're over here...heh heh...
 
"Midlife" said:
Pete:
We'll need to check the anti-siphoning capability the next time you're over here...heh heh...

I have a ball bat that pretty much fixes that problem......
 
This is all very good news. I remember being very annoyed at never being able to use the auto shutoff feature. All my other cars I set the auto shut off and then go check the oil and clean the windshield while the tank is filling. Never could do that with the fastback.

On another note, has anybody seen the new '10 F-150 fuel cap design? Or rather, the fact that there is no cap? Just open the door and stick in the nozzle, no separate cap to remove. Would be interesting to see how that is designed, and how quickly one can be found at a yard to play with.
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