Fuel read out, fault?

Soldato
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Recently became the owner of a RS300 Trophy 2020. Purchased from a main Renault dealer so has its warranty. I'm experiencing an issue with the fuel gauge.

Basically when I get to about 70ish miles left in the tank I start to think about topping up soon but not necessarily right away as it's got plenty left etc

Anyway with this car I've noticed that when I get to this point the car will suddenly drop to 10 miles remaining, needle to empty, fuel light on and a beep sound to warn me.

For example got home the other day, 70ish miles left in the tank, no fuel light on.

Turned car on next day, drove 2 minutes up the road and suddenly 10 miles remaining, fuel light on needle at zero.

This seems like a fault to me. I've contacted them and booked it in for investigation Tuesday. Just concerned as they said it will cost £130 to investigate. If their findings are covered under warranty then that fee is waived. If not then I have to pay it.

Had the car like 3-4 weeks and it's done this each time I've neared the thought of needing to top up soon but not yet.

Makes you not trust it completely

Any similar issues or known faults that this could be?
 
Associate
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I've read about a fair few issues with the gauges on Kadjars and Meganes. I'd assume they all use the same instrumentation and parts with regards to the gauge and sender. They just behave in a very French manner.

I do remember reading something about the first half (From full to 1/2) being controlled by the fuel sender, then the last half having something to do with the trip computer and what sort of driving / economy you're getting. Might make sense with you parking up at 70 miles left, then starting up again and it perhaps thinking it's in an urban situation and dropping the meter down. I'm probably talking complete nonsense though. I just fill up before the light comes on. I do know that the remaining range on the trip computer is based on current fuel consumption though, so what you're getting on your driveway won't be the same as on the motorway. (Sorry if that's being captain obvious).

My Megane goes through the first and last 1/4 tank slowly, but the 2nd and 3rd more rapidly, by what the meter says, however it doesn't have such extreme a swing as yours does. It's a quirk you'll learn to judge if it's something they can't fix.
 
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Soldato
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Does it drop from 10 miles, or is that the lowest it goes? I have a feeling some cars might not read lower than a certain minimum...in my girlfriend's car, once the miles remaining drops to something like 30, it then just displays "- - -".

I figured this was due to it not having 100% guaranteed accuracy, so it's a measure to prevent you from relying on it on it right down to the wire. Basically, "this is your last warning so go fill up". That said, if your car was doing the same thing, leaving the display at "10 miles" would be even more misleading.
 
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Does it drop from 10 miles, or is that the lowest it goes? I have a feeling some cars might not read lower than a certain minimum...in my girlfriend's car, once the miles remaining drops to something like 30, it then just displays "- - -".

I figured this was due to it not having 100% guaranteed accuracy, so it's a measure to prevent you from relying on it on it right down to the wire. Basically, "this is your last warning so go fill up". That said, if your car was doing the same thing, leaving the display at "10 miles" would be even more misleading.

Renaults do do this, at a certain point stops reading anything at all, just -- apparently. I've never gotten that low! Probably to stop you dragging all the rubbish in the bottom of the tank into everything and avoid liability for running out of fuel in the middle of nowhere. Even if it's your own fault!
 
Associate
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does the trip computer work correctly? and did you buy the car brand new?


there is a known issue with renaults if the computer doesnt work correctly but not just one part it all has to have problems ie range to fill up distance travelled mpg etc:)
 
Soldato
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Renaults do do this, at a certain point stops reading anything at all, just -- apparently. I've never gotten that low! Probably to stop you dragging all the rubbish in the bottom of the tank into everything and avoid liability for running out of fuel in the middle of nowhere. Even if it's your own fault!

The pickup is at the bottom of the tank, it always sucks fuel from the bottom.
 
Associate
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The pickup is at the bottom of the tank, it always sucks fuel from the bottom.

Well... you wouldn't want it mid way up would you? Having never looked inside a cars fuel tank I wouldn't know what the interior arrangement is like with baffles and such. I just know a common frame of thought is try not to run on fumes as you're more likely to suck any debris into the filter. No idea if it is right or wrong but as it's easy to not run so low on fuel I've never bothered checking.
 
Soldato
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70 miles was the estimate based on how you were driving before. 10 miles is the 'revised' estimate based on how you are now driving (probably averaging 0mpg for the few minutes whilst you get going, low 20's as you warm up) etc.
 
Associate
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What debris? It's a plastic tank which is filled with liquid and nothing more. There's nothing getting into the tank from outside in the first place.

Over the lifetime of the vehicle stuff is going to get in, dirty car, a small amount falls on the filler inlet and then makes its way in as you fill up. A tiny amount sure, but it'll add up over time. Why bother fitting a fuel filter if nothing is going to get in the tank?

Then you have the condition of older fuel stations storage tanks, maybe they have debris in that can get passed on? *Shrug*.

Not that it's an issue, as I said, it's just the (perhaps old now) common suggestion that you don't want to run on fumes that I was mentioning.
 
Soldato
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Pretty sure my old R19 16v used to do this back in the day - you couldn't trust the fuel gauge when it got really low. I figured it was just that car. Sad to see matters haven't improved much in the last ooooh 23 years!
 
Soldato
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Over the lifetime of the vehicle stuff is going to get in, dirty car, a small amount falls on the filler inlet and then makes its way in as you fill up. A tiny amount sure, but it'll add up over time. Why bother fitting a fuel filter if nothing is going to get in the tank?

Then you have the condition of older fuel stations storage tanks, maybe they have debris in that can get passed on? *Shrug*.

Not that it's an issue, as I said, it's just the (perhaps old now) common suggestion that you don't want to run on fumes that I was mentioning.
This is why cars have fuel filters fitted?
 
Associate
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This is why cars have fuel filters fitted?

Yes but you wouldn't want to clog it if you can avoid it? And running on fumes is easy to avoid? Even if in reality it's not going to be much that gets into the filter and won't cause any problems anyway, like I said, I get that and it's an old suggestion that isn't as relevant as it used to be.

God motors is as obtuse as ever.
 
Soldato
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This is why cars have fuel filters fitted?
I said this to a mechanic once and he asked "how many tanks have you looked in?".

I even rebuted with "but the feed is at the bottom".

Nevertheless, filling my "on fumes" MK6 Fiesta diesel with a fresh tank got it out of limp mode.
 
Soldato
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Well... you wouldn't want it mid way up would you? Having never looked inside a cars fuel tank I wouldn't know what the interior arrangement is like with baffles and such. I just know a common frame of thought is try not to run on fumes as you're more likely to suck any debris into the filter. No idea if it is right or wrong but as it's easy to not run so low on fuel I've never bothered checking.

Any debris supposedly at the bottom of the tank will always be getting sucked up no matter how much fuel is in the tank. There's a pre-filter on the pump to prevent damage to the pump from lager debris, then a regular fuel filter after the fuel pump which is much finer to protect the injection system.

My point was, running low on fuel and sucking debris up is a complete myth :)
 
Soldato
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Any debris supposedly at the bottom of the tank will always be getting sucked up no matter how much fuel is in the tank. There's a pre-filter on the pump to prevent damage to the pump from lager debris, then a regular fuel filter after the fuel pump which is much finer to protect the injection system.

My point was, running low on fuel and sucking debris up is a complete myth :)
Wrong.
 
Soldato
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Fill up with fuel, reset the odometer.

Drive normally until it has this "bug". Go home, take a jerry can of petrol with you, 5 litre or whatever.

Then drive it around your local area and see how far it'll go, keep an eye on the mileage. You'll soon find out if it really has 10 miles left or not. Then you'll get a rough idea for next time, EG oh ****, I really do only have 10 miles left or, not.

I have had many motorcycles (including my current!) that doesnt even haev a fuel gauge you just have to use your loaf. Its far better than any ****** french electronics ;)
 
Soldato
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I don’t understand the £130 diagnostic fee. It’s an almost new car, it has an issue, the car is under warranty.

Book it in, leave with them to fix and collect when ready.

Why does it need to be anymore complicated than that?
 
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