Fuel Gauge Fix
Discussion
Apologies for the longish post, but stick with it.
So I am quite bored today so decided to investigate making a fix for the fuel gauge.
I am at the point where I think I can make a fix that makes the readings a bit more reliable. In order to make the fix applicable to more than just my Mk 1 car I would like some help with calibrating the tank on a number of atoms. The procedure I carried out was as follows.
PART A
i) Wait until car is almost empty of fuel
ii) Put voltmeter across fuel sensor out put and ground
iii)Goto petrol station, ideally at a quiet time
iv) Fill up car recording voltage across the sensor approx every 2 litres dispensed (ignition must be on during fill up, motor does not have to be running).
v) Also record the dash display fuel level at each point (I forgot to do this)
Having done this I now have an idea of the voltage output by the fuel sensor for various fuel levels.
PART B
Next step is to investigate what fuel level the dash displays for various sensor voltage levels, probably can't do this until tommorow when I have borrowed some kit from work.
Using the data from parts A and B I will devise a small circuit which translates the voltages from A into the voltages expected by the dash in B, thus making a reliable gauge.
What would be useful is for more owners to carry out PART A of the procedure and send me the results, this will enable me to make a fix for MK1 and MK2 cars.
It sounds more complicated than it is, an alternative would be for me to carry out PART A next time a nucleus of Atoms meets up and all need to fill up.
Ben
So I am quite bored today so decided to investigate making a fix for the fuel gauge.
I am at the point where I think I can make a fix that makes the readings a bit more reliable. In order to make the fix applicable to more than just my Mk 1 car I would like some help with calibrating the tank on a number of atoms. The procedure I carried out was as follows.
PART A
i) Wait until car is almost empty of fuel
ii) Put voltmeter across fuel sensor out put and ground
iii)Goto petrol station, ideally at a quiet time
iv) Fill up car recording voltage across the sensor approx every 2 litres dispensed (ignition must be on during fill up, motor does not have to be running).
v) Also record the dash display fuel level at each point (I forgot to do this)
Having done this I now have an idea of the voltage output by the fuel sensor for various fuel levels.
PART B
Next step is to investigate what fuel level the dash displays for various sensor voltage levels, probably can't do this until tommorow when I have borrowed some kit from work.
Using the data from parts A and B I will devise a small circuit which translates the voltages from A into the voltages expected by the dash in B, thus making a reliable gauge.
What would be useful is for more owners to carry out PART A of the procedure and send me the results, this will enable me to make a fix for MK1 and MK2 cars.
It sounds more complicated than it is, an alternative would be for me to carry out PART A next time a nucleus of Atoms meets up and all need to fill up.
Ben
Ahhh! Takes me back to my old days as a TVR owner. This involves the customer (having paid 40 or 50 grand) with the privelidge of being the test pilot and fixer of thier own new car!
Why should you have to work this one out. It would seem that this is a well known problem with the Atom and has been for a while. Perhaps they should pay you to sort it out for them, whilst they concentrate on how to get 300 BHP from a 300!
I hate to seem negative, as I am a huge fan of the Atom and will be buying one but as a new club and forum member I have had the chance to go back over the threads on the forum and see the same few silly but annoying issues cropping up. These seem easily fixable if Atom were keen to to it. Rattles, poor headlights, faulty fuel gages and sub quoted BHP.
The Atom is not a cheap car and Simon and the gang are justifiably proud of it but don't seem from what I have read here, to be able to spend the time and money perfecting things, which seems to be contrary to their mission statement.
D.
Why should you have to work this one out. It would seem that this is a well known problem with the Atom and has been for a while. Perhaps they should pay you to sort it out for them, whilst they concentrate on how to get 300 BHP from a 300!
I hate to seem negative, as I am a huge fan of the Atom and will be buying one but as a new club and forum member I have had the chance to go back over the threads on the forum and see the same few silly but annoying issues cropping up. These seem easily fixable if Atom were keen to to it. Rattles, poor headlights, faulty fuel gages and sub quoted BHP.
The Atom is not a cheap car and Simon and the gang are justifiably proud of it but don't seem from what I have read here, to be able to spend the time and money perfecting things, which seems to be contrary to their mission statement.
D.
Personally I don't think the solution is going to be as simple as it seems.
I believe most fuel gagues work on the principle of a varying voltage. Obviously (I think) the voltage arriving at the gauge in the Atom is varying a great deal hence the inconsistent readout.
My bet is the problem is in the tank - the sender.
JC
PS John, yes, had to do some work!
I believe most fuel gagues work on the principle of a varying voltage. Obviously (I think) the voltage arriving at the gauge in the Atom is varying a great deal hence the inconsistent readout.
My bet is the problem is in the tank - the sender.
JC
PS John, yes, had to do some work!
datasafe said:
Personally I don't think the solution is going to be as simple as it seems.
I believe most fuel gagues work on the principle of a varying voltage. Obviously (I think) the voltage arriving at the gauge in the Atom is varying a great deal hence the inconsistent readout.
My bet is the problem is in the tank - the sender.
JC
PS John, yes, had to do some work!
I am beginning to agree. The problem in a nutshell is that the sender is not calibrated to the shape of tank so does not give an accurate view of what fuel you have.
What I know from my experimentation is
i) What voltage the sender outputs for various levels (test done whilst filling tank)
ii) What voltage the dash needs to see to display various levels.
So 'all' I need to do is make a simple widget to convert the sender voltage to the correct dash voltage. Cheap microprocessor, bit of rom, bit of ram and we're off.
Ben
datasafe said:
I wonder if you could simulate the circuit design using Electronics Workbench or simular?
Just a thought before going into production - althong the price of silicon is so cheap these days!
JC
'production' makes it sound a bit grand. I have a circuit in mind and will get the bits for free by abusing my position and blagging free samples for 'a million selling product development'. I will be making a prototype next week on good old veroboard.
Ben
I suspect that there are 2 factors making the readings unreliable.
The first is the shape of the tank so that the readings from the sensor aren't in direct proportion to the fuel in the tank. It should be possible to get much closer to a true reading using the scheme Ben has got in mind.
The second factor is probably something like "slosh" of the petrol in the tank as the car moves. Unless the tank is filled with some sort of honeycomb structure the fuel level probably moves about quite a bit with the car on the move. This might be harder to fix. At least with the calibration setup it should be possible to get a true reading when the car has stopped and the fuel settled or when running along the flat at a constant speed and direction.
Nick
The first is the shape of the tank so that the readings from the sensor aren't in direct proportion to the fuel in the tank. It should be possible to get much closer to a true reading using the scheme Ben has got in mind.
The second factor is probably something like "slosh" of the petrol in the tank as the car moves. Unless the tank is filled with some sort of honeycomb structure the fuel level probably moves about quite a bit with the car on the move. This might be harder to fix. At least with the calibration setup it should be possible to get a true reading when the car has stopped and the fuel settled or when running along the flat at a constant speed and direction.
Nick
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