Reader Question: Gas Cap Gimmick?

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Here’s the latest reader question, along with my reply!

Dave asks: Today I was at the gas pumps talking to a lady who had a new pickup She told me there was no gas cap. The truck has some kind of self-operating opening and closing stuff at the top of the filler spout, behind the gas door. I was not impressed. And told her thusly. My vehicles:

1969 Chev 3/4 ton Chevy 402.
1985 LTD Crown Victoria.
1992 Topaz winter car.
1994 Topaz summer car.

81 years. I repair all of them in my shop. And rebuild some. I use them all at various times of the year. Plain to see, I am odd-ball. Really appreciate your columns!

My reply: All new Fords (and a number of other vehicles) have what are styled “capless” fuel fill systems. Instead of a physical cap that is screwed on and off, there is simply a fill neck with a flapper valve; one inserts the nozzle and that’s it.

The reason for the system isn’t primarily the convenience of the owner; it’s to deal with evaporative emissions (gas vapors) which like all forms of vehicle emissions are under close scrutiny by Uncle. Also, to deal with the Modern Problem of the car’s computer throwing a code – and lighting up the yellow “service needed/check engine” light in the dash – because the driver didn’t tighten the cap properly, allowing evaporative emissions to escape.

These capless systems are relatively new so we have no data to base projections about long-term reliability upon. But I expect that it will involve more money to fix a capless system than to buy a new fuel cap and just screw it on.

Probably, it will involve replacing the entire gas tank “assembly.”

I do know – from experience – that capless systems make it a PITAS to fuel a car by hand, as when you run out and need to pour a gallon in from a jerry can. You need a funnel to insert into the filler neck and then you pour the gas into the funnel . . . trying not to slosh to much of it on the paint!

Also, I have dealt with several capless-equipped new cars that are a PITAS to fill at the pump. Which keeps turning off as you try to pump gas in the car. Apparently, the capless systems are so “tight” that they more readily trigger the pump’s automatic shut-off feature, which is supposed to do that when the tank is near full and it senses resistance. The problem is the capless system sometimes makes the pump think the tank is approaching full before you’ve pumped even a gallon in.

Then you have to find the sweet spot of just enough flow – and just the right position – to get the job done!

One thing I miss most, though, is a feature my ’76 Pontiac has and which I haven’t seen in a new car since the early ’80s: A fuel door mounted in between the rear tail lights, at the back of the car.

I never have to think about approaching a pump from the right side because – in my TA – either side is the right side!

. . .

Got a question about cars, Libertarian politics – or anything else? Click on the “ask Eric” link and send ’em in!

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  1. Just about every car from 1975 on has some sort of flapper door. I haven’t looked too closely at my ’12 Mustang but I assume it’s just one that seals better. I bought a locking plug for it so I have a ‘cap’ for the capless filler neck.

    • Hi Brent,

      Yes, but the capless ones seal much more positively. Which can make adding gas via a can a real PITAS if you haven’t also got a funnel!

      • It may be that the tow truck drivers saw a lot of money not going into their pockets when people put gas into their tanks at the roadside. And decided to do something about it. Like get the feds involved. That’s how the capless systems came about.

  2. I agree. I have a 2019 Lincoln currently and it has one of these “capless” fuel fillers. I also have a 2017 Chevy SS with the traditional gas cap and a cable that keeps it from walking off and allows me to hang it on the filler door out of the way while fueling. I can honestly say the capless filler is no more convenient than the capped filler.

    To look at the capless cap, it sort of looks like it ought to unscrew, and there may, in fact, be a way to detach it in case it needs replacement. It doesn’t seem to be a very expensive or robust piece of technology. It is exactly as you say, basically a normal plastic fuel cap with a spring-loaded flap/valve that covers the hole. The hole is slightly larger than the gas nozzle and about the same as the hole in the pipe of a normal, capped fuel filling opening on every other car I’ve had recently. Older vehicles used to have much more open fuel ports. I believe the newer cars do it this way as gas and diesel fuel nozzles are of different sizes and it helps reduce the risk of idiots putting diesel fuel in their gas engined cars (I forget which nozzle is larger, gas or diesel).

    For fueling via a gas can, Lincoln includes a plastic funnel along with the spare tire and jack in the back. This funnel is designed to keep the flapper valve open and aid in fueling by way of a gas can. As you mentioned, though, you still have a pretty limited flow rate due to the small size of the opening.

    Tip: Most modern cars (not all) have a small triangle/arrow beside the gas pump icon on your fuel gauge pointing to the side of the car your gas door is on. The old wive’s tale of the gas pump icon’s hose serving the same purpose, to indicate which side of the car the fuel door is on, is not true. I have had several cars where that has been wrong or flip-flopped, so that is not at all reliable. I’m guessing they don’t put the filler behind the license plate on the back center of the car any longer b/c of safety reasons. One in a million chance of a spark being sent down the fuel filler into the tank?

    • Hi SJ,

      I think the rear/central fuel fill went away for to reasons: Rear-drive cars went away (for the most part) and (for the second) it’s a saaaaaaaaaaaaaaaaaaaaaaaaafety issue.

      In my TA (and older cars similar) the tank is behind the rear axle. In most new cars it’s located farther back, in the area behind the rear seats. I suppose this protects the tank more from deformation/puncture in a rear-end impact and the filler neck from being sheared off.

  3. My Chevelle had the gas cap behind the rear license plate. About the most convenient location for it too. Alas yet another thing the government won’t let us have anymore……


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