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      01-08-2019, 04:15 PM   #23
barryblue
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I had the same problem with the progress bar stopping at 25% when the car had run for a while and it was hot.

I took it into the dealers and they replaced a sensor. That was about six months ago and it has not happened since.

Barry
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      01-08-2019, 04:25 PM   #24
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So nothing to do with the level of fuel but the temperature of the car?
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      01-08-2019, 04:42 PM   #25
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You guys know there appears to be an emergency release for the fuel door inside the trunk and under the little fuzzy panel on the right side of the car?

At least that is what I'm pretty sure it indicated when I took the trunk apart to install the Maxhaust exhaust sound system. It was a bright neon green pull tab and I'm pretty sure it has a symbol on it that hinted it was for the gas door. You can see it in some of the photos of this posting:

https://bmwi.bimmerpost.com/forums/s...7&postcount=87

(I realize that its not a permanent fix for problems, but I also didn't see anyone mention it...)
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      01-08-2019, 08:33 PM   #26
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Quote:
Originally Posted by Ionicsilveri8 View Post
So nothing to do with the level of fuel but the temperature of the car?
In my case it seemed to be related to the temperature of the car. If the car was hot and the fuel tank was low the door wouldn’t open. When the car was cold and the fuel tank was low, the door opened fine.
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      01-09-2019, 01:28 AM   #27
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Quote:
Originally Posted by Coastal i8 View Post
In my case it seemed to be related to the temperature of the car. If the car was hot and the fuel tank was low the door wouldn’t open. When the car was cold and the fuel tank was low, the door opened fine.

Same with my car.

Barry
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      01-09-2019, 09:09 AM   #28
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Dealer just called and said that it had been diagnosed as the pressure switch, they need the car for an extra day “because it’s just such a big job”. Hopefully all will be well tomorrow but it does make me wonder about a fourth year warranty!
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      01-09-2019, 08:56 PM   #29
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Joining the throng. My fuel pressure sensor needs to be replaced. Got stuck on a few 25% and having to use the manual fuel release; but got a warning message today - the car got tested and now waiting for BMW to order the part.
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      01-10-2019, 01:21 PM   #30
evanevery
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Quote:
Originally Posted by Coastal i8 View Post
In my case it seemed to be related to the temperature of the car. If the car was hot and the fuel tank was low the door wouldn’t open. When the car was cold and the fuel tank was low, the door opened fine.
I would bet it has nothing to do with the fuel level or the actual temperature of the car. Its likely that "Low Fuel" is simply when you actually try and refuel...

Modern cars have been drawing a vacuum in the fuel tank when running for many years. Most will even post an emissions error if the fuel cap is not fully locked down as they can't establish the vacuum. That's why the first thing they tell you to check when you get a "Check Engine" light is a loose fuel cap. I expect the i8 is the same.

Furthermore, I believe that the guy who did my delivery at the Welt told me that the "fueling button" relieved the vacuum in the fuel tank to "prepare the car for fueling".

So, it probably also makes NO difference if your car is HOT. If the engine has been running at all, it has likely established that vacuum. If the car believes that vacuum can not be equalized (with the fueling button) then it will likely post an error...

This could be either an issue where the pressure is not actually being equalized (button or valve failure) or the car can't tell its been released (Sensor Failure).

In any case, I bet if you let the car sit idle for a bit the pressure will equalize on its own.

Again, not a long term fix...
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      01-10-2019, 04:19 PM   #31
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Quote:
Originally Posted by evanevery View Post
So, it probably also makes NO difference if your car is HOT.
The first time this happened to me I had been on a long run and the fuel was really low. The display never got beyond 25% and I had to drive off the forecourt without fuelling the car (drivers equivalent of the walk of shame). The next day, I drove the short distance to the petrol station (cold engine) and the button worked fine, straight up to 100%, with less fuel than it had the previous day. Managed to refuel so who knows?

Anyway, I got my car back today, I mentioned the many US comments on this forum where an additional warranty period was added to the pressure sensor and was told that “we don’t do that sort of thing in the UK sir”!

But what they did do for me was to brim the tank so I am going to have to wait a week before seeing if the fix worked. Nice of them to give me free petrol though!
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      01-10-2019, 04:48 PM   #32
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They also sent me a natty little video of the underside of the car...

https://video.citnow.com/vxSXkKZ4-Ln

The amount of tread on the front tyres worried be as they had only been on for 4 weeks and 2000 miles and I had thought that all new tyres started with 8mm tread. Turns out that the i8 tyres start with only 6mm tread from new, it’s apparently something to do with reducing the rolling resistance (or so the Bridgestone technical bloke said). Just means I’ll have to change them quicker!
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      01-12-2019, 12:32 PM   #33
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Quote:
Originally Posted by Ionicsilveri8 View Post
They also sent me a natty little video of the underside of the car...

https://video.citnow.com/vxSXkKZ4-Ln

The amount of tread on the front tyres worried be as they had only been on for 4 weeks and 2000 miles and I had thought that all new tyres started with 8mm tread. Turns out that the i8 tyres start with only 6mm tread from new, it’s apparently something to do with reducing the rolling resistance (or so the Bridgestone technical bloke said). Just means I’ll have to change them quicker!
is that right? sounds wrong to me but if so it explains why they wear out so quick as they have 33% less effective tread than other tyres!
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      01-12-2019, 01:51 PM   #34
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The new i8 Roadster in the showroom had 6mm all round with delivery miles. Just saying...
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      01-14-2019, 11:58 AM   #35
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Quote:
Originally Posted by Ionicsilveri8 View Post
The first time this happened to me I had been on a long run and the fuel was really low. The display never got beyond 25% and I had to drive off the forecourt without fuelling the car (drivers equivalent of the walk of shame). The next day, I drove the short distance to the petrol station (cold engine) and the button worked fine, straight up to 100%, with less fuel than it had the previous day. Managed to refuel so who knows?

Anyway, I got my car back today, I mentioned the many US comments on this forum where an additional warranty period was added to the pressure sensor and was told that “we don’t do that sort of thing in the UK sir”!

But what they did do for me was to brim the tank so I am going to have to wait a week before seeing if the fix worked. Nice of them to give me free petrol though!
Perhaps the short drive you took just didn't have the necessary time to fully pull down the vacuum in the fuel tank.
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      06-08-2019, 09:15 PM   #36
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I just started having problems with my fuel door as well, with it not unlocking.
I thought this was just a mechanical problem with the locking mechanism, but now I'm not so sure.
Today I used the manual release to open the door. When I tried filling the tank, the gas pump kept stopping, like if the tank was full. I tried repositioning the nozzle, but nothing worked. However, I noticed a strong sucking sound coming from the gas tank.
Perhaps the door wasn't opening because the pressure still had not equalized?
I had only driven the car for about half an hour on this occasion. Previously when this occurred, I had driven the car for about 2 hours.
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      06-09-2019, 04:57 PM   #37
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My 2017 i8 has just started having the fuel tank issues too, the pressure is not working out, so I have had to twice now use the manual emergency release. I hoped that as a later model they may have sorted this, but clearly not. Looks like this could be an ongoing problem for the i8 and unless they find a permanent fix the cars achilles heel. Seems like over engineering to me in the original design, so there must be a simple solution.
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      06-09-2019, 11:22 PM   #38
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Quote:
Originally Posted by Maxxsirrah View Post
My 2017 i8 has just started having the fuel tank issues too, the pressure is not working out, so I have had to twice now use the manual emergency release. I hoped that as a later model they may have sorted this, but clearly not. Looks like this could be an ongoing problem for the i8 and unless they find a permanent fix the cars achilles heel. Seems like over engineering to me in the original design, so there must be a simple solution.
Man, that's some bad news.
How bad can this problem me...I mean what's the worst case scenario people are having? I do a lot of driving in the summer....like 200-300 miles one way.
Hope people aren't getting stranded!
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      06-09-2019, 11:25 PM   #39
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One thing I noticed today when refueling.
When I press the fuel door release button, I noticed that it actually says 'preparing to refuel'. Never really noticed that, I just figured it was just a fuel door release button.
Also, at the end of the 'preparation' I noticed the message then said 'ready to refuel'.
So I guess there is some sort of process involved with preparing to refuel and ultimately releasing the fuel door.
Maybe I just didn't wait long enough for the process to complete, and so opening the door manually prematurely interrupted that process.
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      06-10-2019, 04:48 PM   #40
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I am reasonably sure that EVERY single i8 has (or will) suffer this fault.

It's a piece of bad engineering. A sensitive component is in an aggressive environment (fuel tank), and inevitably fails.

BMW improved the pressure sensor on the LCI and Roadster, but these will also fail in time.

The improved sensor was fitted in warranty repaired cars, but again will fail. My second sensor has just failed and has been replaced a few days ago. It's a big job to replace it.

I'm now on my 3rd sensor, and know it's just a matter of time before it fails too.
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      06-10-2019, 04:51 PM   #41
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Quote:
Originally Posted by rastaman777 View Post
So I guess there is some sort of process involved with preparing to refuel and ultimately releasing the fuel door.
Maybe I just didn't wait long enough for the process to complete, and so opening the door manually prematurely interrupted that process.
It depressurises.

The flap will only release when the sensor detects the pressure has dropped enough.

Manual release overrides that.

Needlessly over-engineered, in order to gain a few eco brownie points in terms of emissions
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      06-10-2019, 04:53 PM   #42
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Permanent solution

What we need is an aftermarket hack to fool the car into receiving a fake signal from the pressure sensor, that it has depressurised.

Then it will open the flap even when the sensor fails.
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      06-10-2019, 04:57 PM   #43
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Quote:
Originally Posted by JasH View Post
What we need is an aftermarket hack to fool the car into receiving a fake signal from the pressure sensor, that it has depressurised.

Then it will open the flap even when the sensor fails.
Or a crowbar...
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      06-10-2019, 05:20 PM   #44
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Mine was fixed. Had to remove the gas tank to fix the pressure sensor. Of course this happened WHEN my trunk was also stuck locked. So I had to wait till the car cooled down.
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