(G) Early morning Fuel refilling, Clock cell

Hi All,

I have a couple of questions

1) It is well known that if you buy fuel during the early mornings or late nights you get more amount of it as the density would be higher at lower temperatures. My question is that if you fill up your tank at say early morning, then would the tank overflow in the afternoon? How much advantage is there with this fuel buying in the mornings? say for a liter of diesel that one buys in the morning, how much more is he getting (compared to in the afternoon)? 10 ml? 20 ml?

2) I have a Uno Diesel. How does one open the clock on the dashboard to replace the battery in it? is it a button cell?

Devakanth

the clock will be powered of the cars power system
the fuel benifits are minimal and not something i would wrry about.
if your happy to time your fuel fill ups to benifit then its fine but for me ,easing of the power a bit would reap more benifits

well in my opinion

if you make a special trip to the petrol station and then drive home, your not gaining anything as you will use petrol on the way back!!!

I was confused about the fuel benefits as most of the sites that I've visited to mentions about this morning time refuelling.

My dashboard clock gets reset everytime I switch off the engine. If it is powered by the car battery, then could something be wrong with the wiring?

Devakanth

I think the clock has two supply feeds - one with the ignition switched on (causes the clock to light up) and one with the ignition off (keeps the time).

Sounds to me like the 'ignition off' feed is lost?

Probably the fuse has blown (is it shared with the cigarette lighter and the interior light - are they working?) Sorry I'm a bit vague but it's hard to say if the wiring in your (much newer) Uno is the same as the older models

-Alex

The cigarette lighter and interior lights are working fine. I will check all the other fuses also, just in case the the supply feed fuse with the ignition off is blown off.

Thanks.
Devakanth

Dev,

Where in India ae you Exactly ??

I also got a faulty clock, some blocks lights up when it likes to do so..

I am on for a respray soon, so will sort it out then..

Sounds like you have lost the memory wire to the clock, should always be live to save the correct time on the clock.
If you have no power up there with the ignition switched off then you could just run a wire straight to your battery + terminal, that way it would have a constant live....
As for the fuel i dont think it makes a difference when you fill up, in fact u kinda lost me on that one..

Hi,

I am in Ahmedabad, Gujarat, India. and still the clock doesn't work. will try to find out where the wire comes from the battery to the clock.

Devakanth

The reasoning is that you buy fuel by volume and it expands and contracts with temperature (that's why if you fill up and then park in the sun you can get an overflow).

So, if you buy 10 litres at 10 degrees and let it warm up to 20 degrees you'll have 10.015 L so compared to buying 10 L when it's already at 20 degrees, so you have 0.015 L for nothing.

(I can't find the figure for petrol so have used the figure for water, I'm guessing petrol is of a similar expansive-ness)

Because petrol is stored underground I suspect the temp will vary very little - you may well get more in January (when the ground around the tank has had time to cool) compared to September (when it's warmed up over summer), but I wouldn't expect to get much advantage between 8 am and 2pm.

If it was stored in an above ground tank (as diesel sometimes is) there might be some advantage.

Alternatively put a block of wood under the loud pedal so that you can't get it to go all th eway to the floor - that'll save more fuel

John

The next question would have to be though, does the engine use more petrol when it's warm and expanded... I suspect that it would?

I don't want to pour cold petrol on your reasoning, but I would have thought that petrol expands far more than water (lending greater credence to your reasoning of course!) - otherwise, the fuel tank would not need vapour-management, or at least, there would be a huge problem with the coolant in the engine expanding more than the capacity of the expansion tank? But I'm guessing too, because I can't find the expansion coefficients for water or petrol!

This works in my Uno Turbo, where the very-large floor mat has to be folded up the wall of the footwell, restricting the accelerator quite effectively.
My Stilo came with double floor mats (both 'fitted' mats, and 'not-fitted' mats with Abarth logos) which achieves a similar result.

-Alex

eeerrr... I knew I shouldn't have replied

Assuming each squirt of petrol is the same volume (don't know if that's true) then a squirt of warm petrol has less energy than a squirt of cold, so the engine gives less power and you put your foot down more; whether the foot down equally balance the less dense fuel I don't know.

I wonder if clever injection systems (ie not Uno ones!) take this into account?



You may be right, or you may not - I have no idea!!! does anyone else know (or care!)

I think that the engine would give different power with the same volume of fuel at different temperatures. But am not sure that the difference is so much as to be noticeable. maybe a very controlled experiment would tell us.

Computer controlled fuel injection systems may be taking care of this but am not sure. But now I've started to care less about the fuel filling in the morning and concentrate more on gear changes and slow acceleration to save on fuel.

Devakanth