Fuel gauge discrepancies

[acdii]

This is a sore subject for some, and I noticed this morning a HUGE discrepancy on mine. I had filled up yesterday, put in 1.2 gallons more than the trip said I used, and the gauge was in the RED. It only took 10.64 gallons to first click, second click added.2 gallons. According to the pump, it was full to the top. This morning though, only having put 66 miles on, the fuel gauge was down 3/8ths from full. By my rough estimate that is 4.5 gallons of gas used for 66 miles. 13.5 gallon tank, 1.5 gallon reserve would put it at 3 gallons per quarter.

 

When I got to work this morning, trip 2 showed I had used only 2.5 gallons over 94 miles, but the fuel gauge was hovering over 1/2 tank. Making an appointment for Saturday to get the oil change and tire rotation done, and will bring this up too. Wildly inaccurate!

 

 

 

 

I have no complaints about the MPG, its frigging COLD out sub zero temps, and getting 37 MPG is right on the money from my estimates, exactly what I expect to see, however, IF the gauges are off, then 37 is a pipe dream, If the actual fuel used is roughly 5.5 gallons, the car is only getting 17 MPG. That is a HUGE problem if its true, then I will have an issue with MPG. I might fill up again today just to see how many gallons were actually used. I have never had the fuel gauge go down that much on a work trip.

[ptjones]

I'm wondering how level the car was when you filled up. Surprisingly the FFH fuel gauge goes down very quickly at the beginning as compared to CMAX's, but seems to stay in the center for quite awhile. Also I think it still had 1.5gal in tank when it turned red. Also maybe the pump was super sensitive. :)

 

Paul

[hybridbear]

This is a sore subject for some, and I noticed this morning a HUGE discrepancy on mine. I had filled up yesterday, put in 1.2 gallons more than the trip said I used, and the gauge was in the RED. It only took 10.64 gallons to first click, second click added.2 gallons. According to the pump, it was full to the top. This morning though, only having put 66 miles on, the fuel gauge was down 3/8ths from full. By my rough estimate that is 4.5 gallons of gas used for 66 miles. 13.5 gallon tank, 1.5 gallon reserve would put it at 3 gallons per quarter.

 

When I got to work this morning, trip 2 showed I had used only 2.5 gallons over 94 miles, but the fuel gauge was hovering over 1/2 tank. Making an appointment for Saturday to get the oil change and tire rotation done, and will bring this up too. Wildly inaccurate!

 

I have no complaints about the MPG, its frigging COLD out sub zero temps, and getting 37 MPG is right on the money from my estimates, exactly what I expect to see, however, IF the gauges are off, then 37 is a pipe dream, If the actual fuel used is roughly 5.5 gallons, the car is only getting 17 MPG. That is a HUGE problem if its true, then I will have an issue with MPG. I might fill up again today just to see how many gallons were actually used. I have never had the fuel gauge go down that much on a work trip.

Our car is doing the same thing on this tank. Trip Meter shows 4 gallons used but gas gauge shows under half a tank remaining...

[acdii]

Well filled the tank again today. Large difference again between the trip and actual. Nearly a 1.4 gallon difference.

 

 

 

 

Thats a 10 MPG difference.

[hybridbear]

Perhaps the cold makes it more inaccurate...

[ptjones]

Do you think it might be the amount of Ethanol in the gas?

 

Paul

[jmellen]

I read on another post elsewhere in this forum that the FFH actually computes the gas gauge reading shown on the left hand screen. Apparently it does not use a sender unit like most vehicles. The post stated that due to the shape of the tank that would not be a linear function anyway, which makes sense. If the above is true it would take a little bit perhaps for your car to 'learn' the correct gauge setting. I have found my gauge to be accurate but the amount reported consumed at fill up time on my trip odometer is almost always low by 5%. I would be curious to know if anyone knows if there is a way to change the calibration of fuel consumed. With so much computerized on the FFH I would think it could be adjusted programatically. The Ford dealer did not know.

[hybridbear]

Here are my current pics. The DTE + miles driven add up to about 460 miles. At 40 MPG this is 11.5 gallons which is plausible with the car being slightly inaccurate and having a ~1.5 reserve when the DTE hits 0 miles. The level on the gauge seems low for only having used 52% of a full tank, but it seems like the car might have evened itself out now compared to what I noticed earlier in this tank.

 

[ptjones]

Interesting to see how it works out.

 

Paul

[acdii]

I just noticed now that the fuel gauge in my last picture shows above the full mark. I rarely see that. Oh well, it is winter, and a CoLd one at that. Not looking forward to monday when it will be a high of -9 and a low of -22 with a 22 MPH wind.

 

Hey Canada, COME GET YOUR WEATHER!!!

[hybridbear]

I just noticed now that the fuel gauge in my last picture shows above the full mark. I rarely see that. Oh well, it is winter, and a CoLd one at that. Not looking forward to monday when it will be a high of -9 and a low of -22 with a 22 MPH wind.

 

Hey Canada, COME GET YOUR WEATHER!!!

Our Monday will be worse lol high of -15F and low of -27F...

[acdii]

4 degree difference. COOLLLLLLDDDDD BRRRR.

[corncobs]

Must be nice to have some winter weather. I can't wait to get back maybe we can grab some of the 40's F from around here and bring it with us.

 

Friends went by the our house today and FFH is turning on and running while the Explorer isn't saying anything anymore with a dead battery.

[FordService]

This is a sore subject for some, and I noticed this morning a HUGE discrepancy on mine. I had filled up yesterday, put in 1.2 gallons more than the trip said I used, and the gauge was in the RED. It only took 10.64 gallons to first click, second click added.2 gallons. According to the pump, it was full to the top. This morning though, only having put 66 miles on, the fuel gauge was down 3/8ths from full. By my rough estimate that is 4.5 gallons of gas used for 66 miles. 13.5 gallon tank, 1.5 gallon reserve would put it at 3 gallons per quarter.

 

When I got to work this morning, trip 2 showed I had used only 2.5 gallons over 94 miles, but the fuel gauge was hovering over 1/2 tank. Making an appointment for Saturday to get the oil change and tire rotation done, and will bring this up too. Wildly inaccurate! ...

 

acdii,

 

Let me know what your dealer has to say. I'll get your CSM involved if you still need help.

 

Ashley

[Osofast]

Acdii, i have a very similar thing happening with my FFH also. I was computing that my mileage was around the same as your around 37 however it is taking more gas in when filling, than what the trip meter says has been used.

Im in Ma. and the cold weather started here about Nov. and it seems so did this problem.

I think it is an issue with the cold, winterblend gas/ethanol and expansion in the tank.

It seems much worse this year in the cold than last year since the "better fuel mileage PCM update in the summer".

I also believe there is still an issue with my car running cold, my commute is only 4.8 miles on a cold day i will remote start to let the car warm up in the driveway for 10 to 15 minutes and then drive to work outside temps ranging from 40-25 f by the time i get to work I'm just getting into the first line of normal temp on the gauge.

Edited January 3, 2014 by Osofast

[hybridbear]

I also believe there is still an issue with my car running cold, my commute is only 4.8 miles on a cold day i will remote start to let the car warm up in the driveway for 10 to 15 minutes and then drive to work outside temps ranging from 40-25 f by the time i get to work I'm just getting into the first line of normal temp on the gauge.

Grille covers will help with that. Check out this thread.

[hybridbear]

Trip meter said 11.38 gallons used, but I put in 13.03 gallons

 

ET Mode DTE was down the lowest I've seen

 

ET Mode FLPM (Fuel Level Percent of Maximum) was the lowest I've seen too, 2.2% or .3 gallons

 

After filling the tank the FLPM shows 99.5% or 13.4 gallons

 

We'll see how this tank does. The old FFH was never this far off in summer. Back last winter I didn't pay as much attention as now to know if it was inaccurate like this last winter.

[acdii]

It has been entered into the system for mine, so maybe something will come up with it. My SM agreed that didn't look right either. Also mentioned I can never seem to put more then 10 or 11 gallons when its way past empty.

[ptjones]

I wonder if they can come up with a software fix ware you could put in actual gal. and it would adjust the numbers so they are closer after a number of fill ups :)

 

Paul.

[acdii]

Source of discrepancy found! I finally got around to documenting the trip screen prior to shut down and after startup.

 

When I got to work this morning, I took a picture of Trip 2 moments before shutting the car off so I would have a record of run time, and fuel used. I had forgotten to take the picture, so I started the car without the brake being pressed, so reason for CEL.

 

 

When I went out to lunch, I had remote started the car, called my wife to let her know I was on my way to get her, then noticed the snow on the car and proceeded to clear the snow. By the time I got in the car ready to start it(did not check to see if it would start without pressing the brake(sorry different thread)), it had been running for at least 5 minutes or more. I had the camera ready and as soon as I pressed the button, and the screens cleared, took another picture.

 

 

So it appears that remote start run time is not accounted for, nor is fuel used during that time. This would explain the gallon and a half difference between what the trip said was used and what was actually put in, and also explains why the fuel gauge and DTE doesn't correlate with reported MPG. Going back to the PDF posted in another thread on how the Fuel gauge is used, this makes perfect sense now. It doesn't explain why an apparently empty tank only takes 11 gallons, which I still believe is just a calibration issue between the fuel sender and the PCM.

[acdii]

Pinning topic, and will leave open for comments, but will eventually lock so it doesn't run off tangent. Pretty sure this solves a big question that has been going around on many levels, including MPG with and without RS.

[hybridbear]

This sounds like an error in the code and should be reported through Ashley. It doesn't explain why owners without remote start (like us) have been seeing big gaps in the extreme cold either.

[acdii]

1.5 gallons difference with 4-5 remote starts of under 10 minutes also sounds kind of thirsty too, but does explain the larger difference I am seeing. Usually its within 3/4 of a gallon on each fill. Not saying it is THE answer, but for me it explains the larger than usual differences I am seeing now on my car.

 

The main point I discovered here, and why I pinned it. If you use remote start, it is NOT calculated into fuel used, nor time run on your trip #1 & #2. This also shows that Remote Start is not factored into your averages when you shut off the car.

 

I am calling it, the RS Blackhole!

[FFH834]

Let me start by saying I have a two month old 2014 HyTi with 4500 miles on it and I have filled the tank 10 times now. I see the same fuel gauge discrepancies as everybody else.

 

1. Cold weather isn't the problem. I'm in Southern California and for a month in my area the daytime temps have been in the 70's and 80's.

 

2. I have used remote start 3 times since I have had the car, each time less than a minute.

 

Now for my opinion.

 

acdii you partially solved some of my discrepancies and gave me a theory when I viewed your photo in post #4. I had never seen my fuel gauge display over "Full". When I saw your photo I said "the next time I re-fuel I'm going to continue adding fuel after the second fuel nozzle click off". Usually if I stop fueling at the second click the fuel used indicator and the gas station pump are within .5 of gallon. But this time I added more than a gallon difference for a total of 12.84 gallons! (I had driven until the gauge wasn't even showing red.) After this fill up my fuel gauge was above full like yours in post #4.

 

OK so here comes the meat of my story.

 

On the next fill up I went to a different gas station than the previous fill. (I alternate between the same two gas stations on my work commute. One in my home town and one near work.) The fuel gauge had just turned red but I had to force in 11.11 gallons after 4 click offs! That did not seem right to me as the fuel used indicator was showing 11.35. The fuel gauge was NOT past full after this fill up. Alright so the next day when I started to work, after just 15 miles my fuel gauge was showing a black space below full! After 48 miles the fuel gauge was at 3/4 full! My conclusion was, at this gas station in my home town, the car must not be on level ground AND THE FUEL TANK ISN'T BEING FILLED TO CAPACITY EACH TIME. (Caps for emphasis and not yelling) Didn't I read somewhere that the Fusion fuel filler doesn't enter at the top of the fuel tank?

 

So IMO the discrepancy exists because the fuel tank isn't being totally filled after each re-fuel. Examples:

 

Tank A - Assumed full tank. Total miles driven - 430. Fuel Indicator - 11.5 gallons. Actual fuel added - 11.5 gallons.

 

Tank B - Assumed full tank (Added 11.5g from above). Total miles driven - 430. Fuel Indicator - 11.5 gallons. Actual fuel added - 11.0 gallons.

 

Tank C - Assumed full tank (Added 11.0g). Total miles driven - 430. Fuel Indicator - 11.5 gallons. Actual fuel added 12.5 gallons. (Why? Because Tank "B" wasn't really filled to capacity).

 

Tank D - Actual full tank! (Added 12.5g). Total miles driven - 430. Fuel Indicator - 12.0 gallons. Actual fuel added 10.8 gallons. (Either the car isn't level and the tank isn't full AND/OR you stop at the first or second click and that isn't filling the tank either).

 

Remember the fuel used indicator is clueless as to how much fuel is actually in the tank. You could drive 50 miles and then reset the Trip Mileage and that would mess up your fuel used. Therefore I take the fuel used indicator as a close "estimate" and not necessarily an "exact" fuel used. You discovered that with your remote start findings. Here's a test. Does the fuel used indicator increase if the ICE is running but the car isn't moving regardless of remote start? I haven't really took notice if it does.

 

Needless to say the odd fuel filler design, the strange "all over the place" fuel gauge, and the fuel used "estimate" make for some stressful times in knowing how much fuel is really left in the tank.

 

Hopefully what I wrote is understandable and sounds reasonable.

 

 

[hybridbear]

The DTE and dash fuel gauge are based on measuring fuel in the tank. These are better predictors than looking at your fuel used on trip 1/2. If you want a more precise reading of how much fuel is left in the tank then use Engineering Test Mode.