Well, apart from comments on the size of the fuel tank, it seems that the falcon fuel gauge is not the most accurate gauge on the planet.
So it's good to know that it's not just my GLi

All my previous cars had a heavely damped analogue gauge reading directly from the tank sender - the damped gauge handling fuel sloshing.
Ford seems to have gone down the route of damping the fuel slosh via software in the cluster as evidenced by the instantaneous and average fuel readings when in daignostics mode.

So it seems that it may be some mechanical problem with my gauge and it requires i pull out the cluster after checking gauge reading at a given resistance. Another job to do

The only other question that comes to mind at the moment is how accurate is the tank/gauge sender/segments.
That is, since the tank holds 68 litres, that should give me 17 litres per quarter.
Is this indeed the case for most Ford EF's/EL's out there ?

Cheers.

They arent divided evenly, if your talking about the diagram on the cluster.

Yes twirqurky, thats what i was asking.
So if they are not divided evenly, do you know the rough partitions in litres ?

Just another thing i noted today.
When i start the car in the morning, shouldn't the average and instant fuel level shown in diagnostics mode be equal ?
In my case they are not, but when driving, occasionally they agree.
Is it that the average level at startup is what it was on shutdown ?
Hardly an accurate way of doing it if this is the case.

Guess it's to the decade box and do a resistance check towards the cluster:)

One would think a fuel gauge is a simple thing to get right but in this case i think ford has let many down

Cheers.

mine does the same sometimes, last time it happend i filled up and I was driving along and the fuel light came on.. weird as.. I even checked if I had aleak lol

try cleaning the contacts on the fuel sender, usually they get dirty and get higher resistance than it should be.
get really fine wet and dry and clean the contacts, and check with a multimeter that when u move the float that the reading is constant and doesnt have any open circuit.

ive noticed that mine drops a quarter evry 100 k's or so

My gauge was like that when i bought it - used to stick at every quarter, but it is running alot smoother now, give it a good work out these days. (*Grumbles* damn fuel economy *grumble*)

Today i checked the accuracy of the instrument cluster fuel gauge by replacing the fuel sender with a decade (resistor) box at the sender plug inside the boot.

As part of my measurement, i set the instrument cluster into diagnostics mode 1 which measures the instantaneous fuel level in litres and the instantaneous resistance of the sender (decade box) in ohms.
For each measurement, i turned the ignition off, set the decade box and then turned the ignition ON for my reading.

I plotted my results in excel which shows that the fuel level is linear with respect to decade box resistance.
Note that the resistance required to show 1/4, 1/2, 3/4 and full within the odometer did not match the values posted earlier
However, as the cluster diagnostics mode shows a close correlation to the resistance of the decade box, it must be assumed that (most of the) cluster electronics are working OK (hense the fuel sender should be OK)

So i suspect that the gauge is stuffed
As my excel graph shows that the fuel gauge needle position is not linear with respect to fuel level (resistance), this makes me think even more so that the gauge is stuffed.

Anyone know how to test the fuel gauge on its own ? That is what voltage or current causes 0/4, 1/4, 2/4, 3/4 & 4/4 needle deflection ?
How difficult is it to remove the fuel gauge from the cluster ?

Cheers.

PS: the low fuel warning lamp only lights with low fuel while the engine is running

PPS: how do i attach jpegs to this post ?

I have always thought it ran off a sensor based on weight. The more fuel yu use = the more you burn = the less fuel in car = lower fuel gague.

Gague needle is easy. Take out cluster, unscrew backand carefully pry the needle off. Its very sensitive.

You sure about the low fuel light is only when engine is running? I know its on in ACC mode

Use imageshack to host pics.

Thanks for that info twirqurky.

Using weight to check fuel level sound too clever for car manufacturers

In my case, when i was checking fuel level by changing resistance, the fuel warning light never came on. Later when i started the car, the light came on as fuel was low but the needle was higher than my low resistance tests

You have me a little worried now so i will check this again tomorrow.

I'll also check out imageshack.

Cheers.

No worries mate..

Using resisitors sounds too clever for me, but I hope I helped.

Agreed.



Cant attach directly... either have hosted and then link... or post in user gallery and link...