[Coastali8]

It seems that a lot of i8 owners have had an issue with the fuel door not unlocking.
My experience has been that after a long drive when things are hot the fuel door remains locked and the progress percentage on the gauge cluster stops at 25%.
When the car is cold and I just drive a few miles to the gas station the fuel door unlocks with no issues.

My question is about the fix. Some have said that a software update has solved the problem. Others have said that the fuel tank must be removed and a pressure switch replaced. They also mention disconnecting coolant lines to get the fuel tank out.

Does anyone have a real world experience and exact fix they can report?

[vance]

Dealership here had to replace fuel pressure sensor and fuel sender to fix that issue on mine

[Jo-Sta07]

I went through this. It's an ordeal. Took it in twice. First they replaced fuel door and second time fuel sensor. Knock on wood it's been fine last thousand miles. I haven't done a long trip though.

[hytek]

Happened to me. They replaced the pressure sensor. Looking good so far.

[FrequentFlyer]

Mine stuck at 25% too when it was out and about but occasionally would open at home.

Needed the pressure sensor fix. The tank has to be dropped down and the coolant lines run underneath it so have to be disconnected as part of the fix.

[mptpa]

Originally Posted by FrequentFlyer

Mine stuck at 25% too when it was out and about but occasionally would open at home.

Needed the pressure sensor fix. The tank has to be dropped down and the coolant lines run underneath it so have to be disconnected as part of the fix.

Happened to me. Dealer came to my house and took it in for service. It was a pressure sensor they replaced and it has been fine so far. But I'm nervous to let the fuel go down to empty.

[Jo-Sta07]

It's an annoyance to say the least. Oddly, the NSX is a hybrid as well and doesn't have to depressurize the fuel door. Not sure why BMW went through the trouble. The i8 mechanic explained it to me but I wasn't totally buying it.

[zagaboo]

Happened to me just once, but I was extremely low on fuel. Never happened again since.

Don't fret, it's very simple to pop the boot and pull the manual release if it is causing issues until fixed.

[Coastali8]

Thanks everyone for the information.

The closest BMW dealer is 1 1/2 hour drive away and the thought of probably leaving the car for a day or two doesn’t appeal much to me.
I tried placing a small plastic plug into the hole on the gas door that would keep the locking pin from engaging and just figured that I didn’t need to lock the fuel door. Seemed like a good idea. But when the locking mechanism discovers it can’t lock the door then the check engine light illuminates. So I guess I’ll wait until I need something additional serviced at the dealer and use the cable release in the trunk until then.

[Aye-eight]

As far as I know, the i8 has a fuel bladder instead of a tank. That is to prevent a layer of air sitting on top of the fuel, which would eventually render it incombustible. I’ve had that happen with one of my classics. Massive nuisance: drain entire tank, replace with fresh fuel, crank engine until all the bad stuff has been sucked through the pipes, hope it fires when the fresh stuff arrives at the engine.

Hybrids are potentially susceptible to that. I haven’t been to a gas station in months.

I think the fuel door release mechanism is there to allow for gradual pressure equalisation rather than a shock event - which would be what the manual release does.

[Coastali8]

Never heard of any car other than the Toyota Prius having a fuel bladder and I think they discontinued the idea about 8 years ago because it didn’t work as designed. The intent was to reduce fuel vapor from building up in the tank and thereby reducing hydrocarbon emissions. Now they use a vapor recovery system probably similar to the i8. The bladder was not intended to keep the fuel from oxidation and going bad from exposure to the air.

I’m not really sure what BMW is doing on the i8 but I really doubt it’s a fuel bladder.

You should probably burn some gas and try to put some fresher gas in the tank on occasion.

[Jo-Sta07]

It's not a fuel bladder they use a stainless steel tank.

[NGR]

Originally Posted by Jo-Sta07

It's not a fuel bladder they use a stainless steel tank.

My dealer said the same - something to do with proximity to the LiOn battery, Stainless Steel is safer in the event of a battery fire.

[Maanpur]

Happened to me twice first the dealership fixed the sensor and 2nd time they end up replacing the fuel tank. No more issues since then.

[Coastali8]

Just received a letter in the mail from BMW.
They have issued a component specific limited warranty extension for the Fuel Tank Pressure Sensor. The warranty for the fuel tank pressure sensor has been increased to 10 years/ 120,000 miles.
This is for “committed to delivering the ultimate in product satisfaction to our customers”

[JasH]

That's decent of them.

I wonder if it also applies to fixed cars? Not that I've ever heard of the fault recurring on a fixed car.

[vance]

Mine was fixed and I got the same letter in the mail

[jcpca356]

got the same letter. that was impressive

[JasH]

I see a pattern.... USA only...

[Maxxsirrah]

Originally Posted by JasH

I see a pattern.... USA only...

i was thinking that. but a clear admission of an issue....

[Ionicsilveri8]

Had this same issue today, couldn’t fill up, the percentage never getting above 25%. The first time this happened my fuel wasn’t that low so I drove home and the following day all was well. Today the fuel was really low so I chose instead to drive to the BMW dealer who was half a mile away. I’m told that it is the pressure sensor so I’ll find out tomorrow!

Whether I get a letter or not is up for debate!

[NGR]

If you use the manual release, be gently with it. I found to my cost that the cable can be pulled clean off the flap. If this happens you can still close and open the fuel door but it won't lock.

I haven't got round to investigating a solution yet.