Fuel Gauge Malfunction

[stephendell]

That’s a late type tank but with an early sender.

I agree with Stephen ........ I have also got out my spare fuel sender and it is a VDO one as is the TSU which I am sure now you do not have. Below is a pic of a TSU for reference.
Thanks for the info on the connector with the metal clip ....... but I was asking about the other one in my last post which has the white cable tie around. It is not really related to our discussions here at the moment ..... it is just my curiosity as it is shown in the manual but unnamed and numbered, so when you have a minute ....
Just going on a bit from my last posts thoughts ...... if you are still awake. My reference to the hole that I said you could see in my pic ..... well having got it out .... that is not a hole ...just a scuff mark. The actual hole X 2 at the bottom of the tube .... see pic below .... is only 1.75mm in diameter, but there are two smaller holes at the top .... 1mm .... which lets the air out of the tube as the tank is being filled. This tends to underline my point that if you switch on the ign too quickly, the tube may not be up to the correct level compared to the fuel in the tank. This will be more pronounced if one is filling a near empty tank. I have not noticed it being a problem as I never let the tank get below say 8 galls. By the time I have gone and payed for the fuel and returned, I suppose the tube has filled up.
Now that brings up another point ......... I appears that because my tank was low, I returned to the car and switched on the ign before the tube was full. Hence the 14.1 galls. I then did a reset but by then the tube was full and the gauge then read correctly 15.1 galls. Now, I wonder ....... had I not done a reset and the tube now being full ...... would the reading have read correctly the next time I switched on the ign ...... My thinking is that it would have as it would just be the same as topping up the tank where the fuel gauge would read the extra fuel topped up.
So I think that if one is having problems with the gauge which does not respond to a reset properly ......... then fill the tank to the brim ..... if possible wait for a period of time before switching on the ign. If the reading is below 15 galls ....... Drive off and pull up after about 5 minutes switch off the ign ...... wait about 1 or 2 minutes ..... in the later Alps case, for the TSU timer relay to drop out, switch on the ign and see if the gauge now reads 15 or so galls. If it does ..... all is well.
There are two pics below one is for the TSU which I think Murf will not have ...... it overall length is just over 5 inches long so you can't miss it.
The other pic is of the very small hole .... 1.75mm x2 ..... that the fuel has to enter the tube when filling. It is certainly going to take a little while to fill from near empty. The vernier gauge is there only for scale.

IMG_2101.JPG

IMG_2100.JPG

A note to Darren .....

I don't think any other car would use such a system,

I think the reason they do it this way is because of the "L" shape of the tank. It would be impossible to get any form of float system to be able to follow the reducing level of fuel as the first .. say, 4 galls ...the level will drop fast than when the fuel level reached the lower section remembering we are measuring to one tenth of a gallon.

That's a very good point John, I think you may have hit the nail on the head there. However seems to me that they missed a trick in then not recalibrating the calculations on each re-start of the engine.
As far as I understood it, the computer doesn't do that, only when it sees the level go up from being refilled.
Still it's a bit like floor hinged pedals, backwards mounted door lock mechanisms or clap-hands wipers... you've got to love it.

Apologies John for the confusion over which connector. The one with the clear cable tie has three black wires, one red wire and one white wire into each side of the block.
I’ve cleaned up the two terminals on the sender and on the supply block and done another reset which has resulted in a reading of 3.9 gals. After a short local spin I now have a reading of 3.5 gals/ 89 miles so maybe things are settling down.
I’m hoping to have more time tomorrow and will try filling the tank to the brim/ resetting as you suggest. I’ll report the outcome.

Murf.

The one with the clear cable tie has three black wires, one red wire and one white wire into each side of the block.

Hi Murf
Thank's for that info ....... the pic in the manual suggests it is a small unit of some kind with wires coming out of only one end. ..... but Hey !!! .... it is a French Manual.
John

I’ve now filled the tank to the brim and ‘hey presto’ the gauge had adjusted to 15.2 gals by the time I got back in the car. Back home now and it’s reading 14.8 gals so seems to be functioning normally at the moment.
Will check the reading again in the morning and maybe do another reset.

Murf.

[stephendell]

Don’t you just love french electrics lol

....... Will check the reading again in the morning and maybe do another reset.

That's Good News Murf.
But if you did somewhere around 10 to 12 miles ..... about the distance to use 0-4 galls of fuel on the way home ...... I would not do another reset. Just make a note of the fuel gauge reading when you switch off ...... and check it is the same the next time you use it.
What I would encourage Alp owners to do, is not let the tank get too low. Your check that it is working correctly is the 15.2 galls ..... or close ..... when you fill to the brim

Checked again this morning an it's still on 14.8 gals so maybe I should just leave things as they are and carefully monitor the situation. Probably need to fill up once the reading gets down towards 4.0 gals to avoid further embarrassment.
Many thanks everyone for the comments and advice.

Murf.

I always carry a 5 litre can of fuel in the boot space just in case

[stephendell]

I always carry a 5 litre can of fuel in the boot space just in case

Me too. Essential service item in a GTA lol

I always carry a 5 litre can of fuel in the boot space just in case

Me too. Essential service item in a GTA lol

Clearly, I'm wasting my time ....... I give up.

[stephendell]

I always carry a 5 litre can of fuel in the boot space just in case

Me too. Essential service item in a GTA lol

Clearly, I'm wasting my time ....... I give up.

No you are always most helpful Personally I don’t trust the gauge from 2.0G down or when the yellow light comes on so I always keep a can in case there is no fuel near by. Not so much of a problem in the UK but in France you could easily have to travel more than 20 miles to find a service station.

Interesting discussion! I am working on a custom replacement fuel computer for my A610 - don't know if the connector is compatible or not, but the general principle should be. It will be self-calibrating and should work with any aftermarket ECU too. It will calibrate the first few times you use it - the principle will be: fill the car to the brim and record the number of litres filled. It will get more accurate the more you use it and request a refuel after a certain amount of fuel has been used, in order to work out how the level changes over time. Obviously it will need to be conservative when the tank approaches empty.

I can start a new thread when I'm ready to publicise it. I plan to offer it to sale as a plug-in replacement.

Andrew