Latest Reader Question (March 15, 2018)

Here is the latest reader question, along with my reply:

Walt asks: During the Florida hurricane evacuations last year our older diesel Silverado truck had to go into an out of town Chevy dealership for a computer related braking problem (sixteen hours of bumper to bumper traffic on the Florida Turnpike and Interstate highways likely exacerbated the brake issue). Probably because the repair was going to cost an arm and a leg they gave us a new loaner car while the truck was being repaired, despite the truck being well over a decade out of warranty.

The point of writing to you about this event is that the new Chevy loaner car (the car was so uncomfortable and unremarkable a species of “modern transportation” that neither my wife nor I can recall what model) did not have a gas cap of any kind. There was a non-locking “fuel door” that closed over the fuel filler tube, but no gas cap, simply a spring loaded flap inside the fuel filler tube.

All our vehicles have locking gas caps (if the vehicle doesn’t have a locking fuel door) because I still remember having to drive to the rescue during the 1970s gas embargo after a vandal siphoned the fuel from a family member’s car while they were at work. I can also imagine some predatory gangsters purposely adding some agent to unlocked gas tanks and following their intended victims until their vehicle’s engine fails and they are left stranded. I mentioned that the car had no gas cap or locking fuel door to the service manager and he said that he had never noticed this before. Is the “old fashioned” gas cap really missing from new cars, or was our new car just an anomaly?

My reply: Many new cars do indeed come this way; that is, they do not come with gas caps at all. They are “capless” – with the usual hole into which you insert the gas pump nozzle. But the hole closes itself after you remove the gas pump nozzle, sealing the fuel system. The reason for these capless systems is – of course – emissions control. Specifically, vapor control.

The capless system eliminates the human variable – a person neglecting to properly tighten the old-style screw-on cap. This also helps avoid the fairly common problem of the “check engine” light coming on because the gas cap wasn’t tightened properly. This triggers a trouble code and – in many cases – it is now necessary to clear the code using a scan tool (see my recent article on this topic) in order to get the light to turn off again.

As far as concerns about vandals and gas thieves: All the cars equipped with the capless system have locking gas doors. Some have to be manually released (by pushing a button inside the passenger compartment) or will automatically unlock when the presence of the key fob transmitter is sensed.

Hope this was helpful!

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