Author Topic: Low fuel reading even when fuel is there  (Read 1009 times)

Bristol_Crosstar

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Re: Low fuel reading even when fuel is there
« Reply #15 on: March 18, 2023, 09:18:52 AM »
I tend to fill up when it goes down to 30% or even a bit later. If you drive around with a full tank you're carrying quite a bit of extra weight with the additional fuel so it affects your mpg adversely.

pebbles

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Re: Low fuel reading even when fuel is there
« Reply #16 on: March 18, 2023, 10:24:22 AM »
have had a few loan cars from the Honda dealer when the Jazz is in for a service or repair, usually only to get home and back.
Put about a tenner worth's in and it never registers , could be embarrassing but the dealer just smiles , they are  well aware of this.

nowster

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Re: Low fuel reading even when fuel is there
« Reply #17 on: March 19, 2023, 12:07:28 AM »
I tend to fill up when it goes down to 30% or even a bit later. If you drive around with a full tank you're carrying quite a bit of extra weight with the additional fuel so it affects your mpg adversely.
It's minimal. A full (40L) tank of E10 is 30kg of mass. That's the same as a child (4st 10lb).

Bristol_Crosstar

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Re: Low fuel reading even when fuel is there
« Reply #18 on: March 19, 2023, 08:45:07 AM »
I tend to fill up when it goes down to 30% or even a bit later. If you drive around with a full tank you're carrying quite a bit of extra weight with the additional fuel so it affects your mpg adversely.
It's minimal. A full (40L) tank of E10 is 30kg of mass. That's the same as a child (4st 10lb).
Any extra weight will increase fuel consumption, I can certainly notice a difference in the handling of the car when there isn't much fuel left compared to when the tank is full. It might not make much difference in the short run but will over an extended period.

If you've ever watched Formula 1 the reason all of the drivers are small is to reduce the weight of the car, and the handling changes completely when fuel is low. I know the Jazz is not comparable to an F1 car but the same laws of physics apply.

nowster

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Re: Low fuel reading even when fuel is there
« Reply #19 on: March 19, 2023, 09:55:10 AM »
I know the Jazz is not comparable to an F1 car but the same laws of physics apply.

With an F1 car, the mass of the driver is a significant percentage of the mass of the whole vehicle. Also they can carry up to 110kg of fuel. The minimum weight of F1 car including driver is approximately 800kg. The addition of a full tank of fuel is a significant proportion (14%) on top. Refuelling mid-race is currently banned.

The Jazz Mk4 is already heavier than a comparable non-hybrid because of the battery and motors. Its kerb weight is about 1400kg. A typical adult driver adds about 75kg. A full tank (30kg) is about 2% on top of that.

peteo48

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Re: Low fuel reading even when fuel is there
« Reply #20 on: March 19, 2023, 10:37:53 AM »
I've never done the "running on empty" lottery. I know people who love seeing how much they can get out of the tank when the warning light comes on.

On the Jazz, I fill up when I am down to the last 3 of the 10 bars.

PS: I say never - I did do it when I was trading in my Civic. Put 5 in.
« Last Edit: March 19, 2023, 10:42:34 AM by peteo48 »

Kremmen

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Re: Low fuel reading even when fuel is there
« Reply #21 on: March 19, 2023, 10:49:46 AM »
That reminds me of a lucky escape I had.

Back in March 2007 I was p/x my Lexus IS200 for my first Civic. Normally I would top up every Sun as my weekly commute was about half a tank.

The Sun before the p/x I didn't top up and that was the weekend the Tesco petrol got contaminated and loads of cars were breaking down within miles of the filling stations round me.

https://en.wikipedia.org/wiki/2007_United_Kingdom_petrol_contamination
Let's be careful out there !

Jazzik

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Re: Low fuel reading even when fuel is there
« Reply #22 on: March 19, 2023, 11:44:58 AM »
I've never done the "running on empty" lottery.
--/--
On the Jazz, I fill up when I am down to the last 3 of the 10 bars.

There is no such thing as a "lottery" here. I often fill up when there is just 1 bar left (yes, that last one ;)). And usually I fill up between 31.5 and 35 litres, so there is still between 5 and 8.5 liters in the tank, which means about 100 to 170 km. Hardly ever seen a low fuel indicator.

For example, we drive on a tank of fuel across Germany from before the Polish-German border to just before the German-Dutch border, some 635 km at motorway speed (around 120 kmh/75 mph). And then the tank is really not empty. We regularly drive between 700 and 750 km on a tank, once an exceptional 875 km.
Coming to a halt with an empty tank is not very realistic in Europe with a petrol station every 30, at most 50 kilometers.

« Last Edit: March 19, 2023, 12:04:49 PM by Jazzik »
If nothing goes right, go left!

Pine

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Re: Low fuel reading even when fuel is there
« Reply #23 on: March 19, 2023, 11:55:05 AM »
If I was concerned about weight in the car reducing fuel consumption I would go on a diet, but I'm not that worried.

When you fly they weigh your luggage.  I have always thought they should weigh the passenger as well as their luggage.
« Last Edit: March 19, 2023, 11:57:20 AM by Pine »

peteo48

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Re: Low fuel reading even when fuel is there
« Reply #24 on: March 19, 2023, 12:01:11 PM »
Jazzik - people do run out of fuel here in the UK. Indeed there are laws against running out of fuel on the motorway network (a fine is the usual punishment) and in various tunnels like the 2 tunnels crossing the river Mersey so people do "play" the lottery and lose. You see this from time to time on various police documentaries.

I take your point though, there is a bit of leeway when hitting empty.

Kremmen

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Re: Low fuel reading even when fuel is there
« Reply #25 on: March 19, 2023, 12:15:57 PM »
From similar threads on the Civic forum it seems that when the tank range says zero you actually have about 50 miles left.

Let's be careful out there !

Lincolnshire Rambler

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Re: Low fuel reading even when fuel is there
« Reply #26 on: March 20, 2023, 06:30:29 PM »
The Jazz has a min kerb weight of 1228 kgs so no doubt a couple of kgs heavier on the EX models with more equipment- even then no where near to 1400 kgs👍

nowster

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Re: Low fuel reading even when fuel is there
« Reply #27 on: Today at 10:33:52 AM »
The Jazz has a min kerb weight of 1228 kgs so no doubt a couple of kgs heavier on the EX models with more equipment- even then no where near to 1400 kgs👍

Just checked. The V5C says 1300kg for revenue purposes. I don't know where the 1400kg figure came from. It still doesn't invalidate my calculations.

The difference between having a full tank of petrol and half a tank (15kg) is going to be minimal.

Lord Voltermore

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Re: Low fuel reading even when fuel is there
« Reply #28 on: Today at 12:09:45 PM »
I think any extra weight from fuel ,eating too many calories ,etc  will have more affect on mpg in urban traffic where  the car is frequently having to haul  that extra weight from 0 mph up to speed. .  Also its less stress running with an almost empty tank when you know you are never far from a filling station.

But when clocking up miles on the open road, once you are up to a more constant  speed  a few extra kilos isnt going to make much difference to fuel consumption. Extra speed and wind resistance will.   
  Trust a dog to guard your house  , but not your sandwich

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