Wierd fuel gauge behaviour (202)

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stevesey

MB Enthusiast
Joined
Sep 3, 2007
Messages
2,969
Location
Bristol
Car
Alfa 156 1.8TS
Not an issue really just an observation (a very sad/**** observation).

I've been working on customer site for the past couple of weeks and this week the 80 mile round trip has aligned itself with the notches on the petrol gauge e.g

Monday - gauge on full all the time (as they do)
Tuesday - first 1/4 used up
Wednesday - second 1/4 used up

after 4 days can't squeeze another trip out of it, so fill up.

Odd thing is what happens it between the 1/4 segments - the past two days I have got on the Motorway (9 miles from home) with the gauge a couple of mm below the top of the quarter segment the needle is in, after about 8 miles of motorway I look down and the gauge has dropped to a couple of mm above the end of the that segment. I then travel the rest of the way to work and back and arrive home with the gauge bang on the next segment. I was trying to keeping a closer eye today, but the car caught me napping and managed to sneek the big drop in over about 3 miles when traffic was distracting me. :rolleyes:

At no point do I notice the gauge regaining the "lost" fuel - even after the stop/start at work.

Wierd...

...a couple of thoughs:

a) Is there a high speed fuel syphoning gang operating on the M4 eastbound?
b) Sudden drop always happens when I'm not looking - perhaps if I look will more my mpg go up?
c) Perhaps I should set up a video to watch the gauge (and the filler cap).

In reality I suspect it's something to with the way the fuel guage is damped and the terrain (windy up-hill section) before getting on the motorway in the morning. Very odd though.
 
Worryingly the reserve light on mine appears to be coming on later and later.
The light came on on the motorway (trundling at 70mph).

3 miles later I filled up and it took 58.5 litres. Thats 2.5 left in reserve!
Given that I should have 7 litres in reserve then either...

a) the switch is a bit dickie
b) at 70 I'm doing 3mpg

More worryingly, given the car averages 27mpg, if the light comes on at 2.5 litres I have to get to a petrol station in 15 miles :crazy:
 
There has been some debate here about whether the quoted tank capacity includes the 7 litre "reserve" or not.
 
Not an issue really just an observation (a very sad/**** observation).

I've been working on customer site for the past couple of weeks and this week the 80 mile round trip has aligned itself with the notches on the petrol gauge e.g

Monday - gauge on full all the time (as they do)
Tuesday - first 1/4 used up
Wednesday - second 1/4 used up

after 4 days can't squeeze another trip out of it, so fill up.

Odd thing is what happens it between the 1/4 segments - the past two days I have got on the Motorway (9 miles from home) with the gauge a couple of mm below the top of the quarter segment the needle is in, after about 8 miles of motorway I look down and the gauge has dropped to a couple of mm above the end of the that segment. I then travel the rest of the way to work and back and arrive home with the gauge bang on the next segment. I was trying to keeping a closer eye today, but the car caught me napping and managed to sneek the big drop in over about 3 miles when traffic was distracting me. :rolleyes:

At no point do I notice the gauge regaining the "lost" fuel - even after the stop/start at work.

Wierd...

...a couple of thoughs:

a) Is there a high speed fuel syphoning gang operating on the M4 eastbound?
b) Sudden drop always happens when I'm not looking - perhaps if I look will more my mpg go up?
c) Perhaps I should set up a video to watch the gauge (and the filler cap).

In reality I suspect it's something to with the way the fuel guage is damped and the terrain (windy up-hill section) before getting on the motorway in the morning. Very odd though.

The same happens to me westbound. Live in Swindon, work in Bristol. I think is just that the litre is over the £1 and we keep very close attention to the fuel gauge nowadays.
 
The same happens to me westbound. Live in Swindon, work in Bristol. I think is just that the litre is over the £1 and we keep very close attention to the fuel gauge nowadays.
I'm going the other way (Bristol -> Swindon) always notice it just before Leigh Delli services.
 
i think you will find that with the cold starts the rear windscreen demister, and heated seats if you have them is straining the engine that little bit extra causing it to use the extra fuel, not to mention any local driving where your stopping and starting.
I find a big difference in my fuel consumption during winter months, i will keep an eye on it

Raj
 

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