[Darola]

I drive a late 2017 420D - Last Sunday, at 11:30pm driving home from a concert, I ran out of diesel, with the needle showing just over half a tank, and the trip showing a range of 250 miles. Roadside assistance brought me 10 litres of fuel and I headed home. Booked the car into BMW the next day, and dropped it off on Tuesday. They had the car for three days, and had replaced the fuel sensor and head unit (software crash they couldn't recover apparently). When I picked it up, it showed just over 1/3 tank, and a range of 168miles. My assumption they've fixed it and put some fuel into test it (remember I'd only added 10litres from dry). Drove home, picked the kids up and all seemed well, the range dropped around 12 miles so must be working. Yesterday we were going on a family trip, loaded the car up - kids, coats, picnic - and set off. With the range showing 154 miles, I ran out of fuel AGAIN! Car is back with BMW and the technician advised this time he'll replace the whole tank - something to do with sensors they can't reach and possible function issues (lost me to be honest). But I can't understand how BMW doesn't have any way to check physical fuel level, to confirm it fits with the reading! Couldn't find anybody else that has had this issue, hence thought I d post this. Picture shows the fuel readings when the tank was actually empty.[IMG][/IMG]

[frazervalley]

Good grief how frustrating. I hope they identify and correct the fuel problem this time.

[Bluebeasty]

Sounds like your shoes are just untied......

[Derek Mc]

I must admit I am one of the few who brims and resets the trip every single tank (I upload to Fuelly) I tend to go on mileage more than the gauge, and I always like to have roundtrip fuelling, so if I plan a long trip I fuel in advance, (just a personal quirk) to ensure I don't waste time on the run,,,,

I am keen to know just what emerges on this however it is very strange indeed

[cfm56d7b]

This is the first time I heard about this problem, whether the engine is diesel or gasoline.

VERY unusual. I am surprised the dealer cannot determine the root cause.

[kingmonkey8]

Originally Posted by cfm56d7b

This is the first time I heard about this problem, whether the engine is diesel or gasoline.

VERY unusual. I am surprised the dealer cannot determine the root cause.

Stuck fuel sender?

[328iX]

Why didn't you reset the trip to see how far you're actually going?

Prepare for a whole fuel system overhaul because running both pumps dry is no good.

[Darola]

In hindsight I did rest the trip, but first time round I doubted myself - as it's a sub conscious action. I work from home a lot and fill up every 2/3 weeks so couldn't recall when I'd last put fuel in. I actually started questioning the fuel level about 50 miles before it ran out the first time, but the guage and range decreased, so I just assumed I'd not reset the trip! Second time I assumed that BMW had put fuel in, so went of the range. I usually fill up when it pings at 45miles to go.

[SteveinArizona]

Originally Posted by 328dX

Why didn't you reset the trip to see how far you're actually going?

Prepare for a whole fuel system overhaul because running both pumps dry is no good.

The OP has a relatively new car, under warranty, why is it unreasonable for him to believe the petrol gauge?

[328iX]

Originally Posted by SteveinArizona

The OP has a relatively new car, under warranty, why is it unreasonable for him to believe the petrol gauge?

Because it had previously failed? Better than getting stranded with no fuel?

[AlpineX]

Originally Posted by 328dX

Why didn't you reset the trip to see how far you're actually going?

Prepare for a whole fuel system overhaul because running both pumps dry is no good.

You can't run both pumps dry unless you crank and crank and crank with no fuel

[328iX]

Originally Posted by AlpineX

You can't run both pumps dry unless you crank and crank and crank with no fuel

So you're implying it's safe to run a car dry, you don't need to keep cranking as it will suck up air when it's low and the fuel moves around the tank.

By all means if you like filling up at the last possible moment go for it.

[AlpineX]

If the hpfp has no fuel, the engine does not run

[AlpineX]

I go below 1/8 tank regularly in about 54k of BMW diesel. The only time I have had a low rail pressure code is when changing fuel filter

[328iX]

Originally Posted by AlpineX

If the hpfp has no fuel, the engine does not run

Who's talking about the engine running, my point is running dry is not good. idc what you say or what your experience is, this is a known fact. Diesel lubricates the pump and air will get sucked in if you run it dry, same with gas engines.
Plan and simple.

Some people just like to argue on here rather than admit they're wrong, jesus

[upsidedownfunnel]

Unfortunately this repair process is pretty standard. There are two fuel level sensors but for obvious reasons they only more easily replaced sensor first. Then if that doesn't fix your issue, they'll replace the fuel tank to fix that. That's how most repairs are done when the source of the issue could equally be multiple parts. Repair the cheapest and quickest part first, then go on to the next.

Also, if you continue to have these issues, I'd highly recommend filling up your car to full before something important like a family picnic. You don't want to be stranded on your day off with your children possibly on the side of the highway. Save the testing for another time like driving to the gym or work.

Also, filling up full tanks allow you to estimate your range. Before car computers gave you your range, some people would reset the trip odometer at every fill up and get used to how much mileage they were getting.

[AlpineX]

Originally Posted by 328dX

Prepare for a whole fuel system overhaul because running both pumps dry is no good.

It stopped immediately when there was no fuel. Fuel system overhaul is for a diesel/ gasoline mix. No reports of cranking to oblivion that I've seen, though possible.

[328iX]

Originally Posted by AlpineX

It stopped immediately when there was no fuel. Fuel system overhaul is for a diesel/ gasoline mix. Obviously.

No it's not, it's when you put in gasoline and that doesn't provide adequate lubrication for the HPFP, which causes it to destroy itself and send metal shavings throughout the entire fuel system. The same thing happens when you're out of fuel, it sucks in air and parts don't get lubricated.

[AlpineX]

Originally Posted by 328dX

Who's talking about the engine running, my point is running dry is not good. idc what you say or what your experience is, this is a known fact. Diesel lubricates the pump and air will get sucked in if you run it dry, same with gas engines.
Plan and simple.

Some people just like to argue on here rather than admit they're wrong, jesus

Yeah. Ok.
Gasoline is a lubricant? Whatever

[AlpineX]

Originally Posted by 328dX

. The same thing happens when you're out of fuel, it sucks in air and parts don't get lubricated.

Car doesn't run on diesel/oxygen mix.

I mean if you habitually get towed to the nearest fueling station then that's another issue

[328iX]

Originally Posted by AlpineX

Car doesn't run on diesel/oxygen mix.

I mean if you habitually get towed to the nearest fueling station then that's another issue

You clearly have no idea what you're talking about and must be trolling, have a nice day

[AlpineX]

Ok mr "I'm 23 and I've owned a bazillion Hondas and have more than 1 rep per day"