Strange glitch with fuel gauge

[FastCoolBlue]

So I'm wondering if anyone else had experienced a similar issue.

When I started my car to leave for work yesterday morning my low fuel chime and light came on and I watched my miles to empty display begin to drop from 55 to 46, 34 to 23, etc, all the way down to 0 and finally ending with just a dotted line across the display. Now when I last parked my car I still had just under a half tank and I've never let my fuel run below a quarter tank so seeing this was quite alarming. I shut the car off and checked underneath to ensure there was no leaks (there weren't) and then called my wife to turn around and come pick me up to take me to work since I didn't have time to get the gas can and go to the gas station and back home to fill the car up. I'm now thinking that someone syphoned my gas overnight but figure I'll deal with it when I get home since I need to get to work.

Once I got home from work, I went to the gas station to fill up my 2 gallon gas can and go back home to dump that in the tank. I start the car up and the fuel gauge needle goes right to the 3/4 mark and I'm thinking WTF? I then drive my car to the gas station to top off the tank and it only takes about 4 gallons to completely fill up. So obviously I experienced some weird bug in the system and have no idea what caused it. My ST is a 2014 with approximately 42,000mi on it.

 

[maestromaestro]

It is indeed strange. What I see when I either disconnect the battery or flash a tune is the MPGs start initially going down from whatever value it starts to about 16 mpg and then, with driving, it gets back to normal. Same happens with the predicted range (miles to empty) - it jumps to over 400 miles - and then starts moving down to realistic values.

The fuel gauge never had any difficulty. And as far as the predicted range goes, if it is in the normal regime, it tends to be quite accurate, and - what I particularly like- it counts down to zero. None of this “low range” or dashes nonsense.

What did the fuel gauge actually show when you saw the mte numbers go down?

 

[FastCoolBlue]

The fuel gauge itself was buried past "E" which is why I assumed I was out of gas.

Another weird glitch just showed up yesterday which may be unrelated but now when I start the car I get this loud tapping noise coming from under the plastic trim panel that covers the touch screen. It sounds like someone is smacking the underside of the plastic with a stick. It's a repetitive "tap....tap....tap....tap...." and does this about ten times. I'm going to pull the panel up this weekend and see if I can identify where the noise is coming from.

 

[maestromaestro]

The fuel gauge itself was buried past "E" which is why I assumed I was out of gas.

Another weird glitch just showed up yesterday which may be unrelated but now when I start the car I get this loud tapping noise coming from under the plastic trim panel that covers the touch screen. It sounds like someone is smacking the underside of the plastic with a stick. It's a repetitive "tap....tap....tap....tap...." and does this about ten times. I'm going to pull the panel up this weekend and see if I can identify where the noise is coming from.

This sounds like the blend door actuator. Very common failure. There are several threads on this subject.

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[FastCoolBlue]

Well that's just fantastic.....

 

[maestromaestro]

Well that's just fantastic.....

You're in a big company for the actuator. I'm on my 3rd one at 70k miles. Apparently, it's a consumable.

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[Intuit]

Here's the longest of the threads on the blend door subject...
https://www.fiestastforum.com/threa...r-Issue-Thread?p=337266&viewfull=1#post337266

Re fuel gauge, haven't run across any similar posts. I wonder whether there are any codes stored in the system?

Were the roads wet when this occurred? Run over anything in the past hundred miles?

Did you get the characterstic 'ding' when it initially showed as low?

Is there anything about the vehicle that isn't stock, or has been worked on?

I believe that is the evap charcoal canister, underneath the rear of the vehicle; no fuel runs through it. But the photo shows where the fuel tank is, and the wire harnesses that feed it. I'd inspect for damage or oddities.

 

[Webhead]

Hey, I wanted to chime in. I ran into the same issue today, I actually have a check engine code to go along with it. I haven't had time to dig into it yet but I'll attach this for anyone else having issues.