Petrol Gauge Readings

Over the winter my petrol gauge has ceased to work correctly.
It never reads more than 2.2 gals and sometimes does not go below this reading.
Today, I stripped the sender unit down and took some readings from it. At the full level the reading was 2 ohms and at the empty reading it was 85 ohms. The manual states it should be 350 + or - 50 at full and 25 + or - 5 at empty.
I have checked all the connections within the sender and even resoldered some.
Anyone have any suggestions or do i need to source a new one?

Have you checked the cable that attaches to the float?

Yes, the very fine wire is intact, and runs freely through the connections on the float.
I have tried to reset the gauge by holding the reset button in, but not with the battery disconnected. Something i will be trying first thing in the morning.
But the readings I'm getting for the resistance have totally thrown me as they appear to be not only way out but back to front, so to speak.

There are two types of sensors, pre 1989, and after. I think the manual shows the earlier one, but as you have a 1990 Turbo, the later sensor will be fitted together with a TSU, and when the tank is full, the resistance of the sensor is at its lowest, and conversely the resistance is at its highest, when the tank is empty.
A full computer reset with the battery disconnected would be worth doing, but hold the reset button for a good 20 secs to be on the safe side.

Thanks John, will try it first thing in the morn and let you know!

At the full level the reading was 2 ohms and at the empty reading it was 85 ohms.

BTW these readings are correct for the later type sensors

Still no joy!
Tried just about every possible way, with the sender upside down, half way but it still reads 2.2 gals.
But at least I know that if the readings are correct then it must be the computer even though mpg and trip meters are working correct.

.....then it must be the computer even though mpg and trip meters are working correct.

.....or the TSU, or the TSU Timer Relay.
Even though the MPG & Trip are working.....these do not require the Fuel level in tank to compute their readings.
Type "TSU" in the Search section for more info on this subject.

BTW have you considered becoming a full member of the club.....there is a wealth of info about these Alps in the members only section

I love my GTA but its a pain in the asp! lol
I've read the threads on TSU's and I'm more confused now than I was before. Where do I locate them on my car?
I've had half the interior apart today, what with this and my ventilation fan problems but the latter is fixed now.
John, I have been meaning to join up as a full member for a number of years now. Maybe now is the time, how do i go about it?

The TSU is situated under the boot liner and on the front of the near side inner wing. You will have to feel for it..... Item 327 in pic.



The Timer relay is behind the panel above the fuse box (3 x screws) and also you will have to hinge down the first bank of fuses (2 x screws) and it is the white one in the middle of th pic.

John, I have been meaning to join up as a full member for a number of years now. Maybe now is the time, how do i go about it?

Print off the application form below, fill it in and send it together with £25 to Stephen

http://www.renaultalpineownersclub.com/ ... N%20V2.pdf

Search the forum for fuel related problems, somewhere there is loads on the fuel.system particularly the float.

Update!
Located both the TSU (inner wing under bonnet) and the TSU Timer relay (behind fuse box). The Timer Relay was not fixed to the back of the fuse box but stuffed above the other relays. It had obviously been played with before as it had a hole in the one end where someone had obviously tried to prize apart in the past (before i owned the car, more than 11yrs ago).
When I removed the wiring block to the TSU and disconnected the battery, reset the computer it gave a reading of 18.7gals. When reconnected and reset went back to 2.1gals.
The Timer Relay removed and computer reset the reading remained at 2.1gals, I noted that the Timer Relay also clicked as I reconnected it.
Should i now remove the TSU and check the readings across it when still connected up.
John, I do appreciate your help on this subject as there seems to be a lot of confusion on what is the TSU and Timer Relay in previous threads.

Glad you have found all the parts ...what I would like you to do now, is to see if the timer relay is operating as it should. This is quite simple. Do a full reset......(as a must when playing around with these parts...every time anything is connected or disconnected a full reset must be done otherwise the next readings could be compromised).... re connect battery, press reset one more time.....Switch ign on.....give it say a minute....put your ear close to the timer relay.....switch off ign, and if the timer relay is working, it should click off around a half to 1 minute later. To be on the safe side it could be longer, but reports have varied as to the length of time the relay stays on for, mine is about half a minute. But if it clicks off immediately... the relay is faulty.
Give that a try and let us know what you find
BTW do you have a multi meter amongst your tools?

The Timer Relay clicks approx 30secs after turning off ignition.
I've opened up the TSU casing to find that connection no.3 was very heavily correded in a green gunk, cleaned it up which led to me having to resolder the spade connection back to the inner arm of the same coonection.
Have carried out full reset but still 2.1gals.
I do have a multimeter, John.

Update!
The 8-pin plug to the TSU is numbered as follows:
Terminals 1 and 2 from the sensor, the reading acroos these are the same as those acroos the terminals of the sensor - 12.7ohms and 0.58v (the tank is all but full).
Terminal 3 is an yellow wire from the relay giving readings of 0v when ignition is off, 12.58v when ignition is on, returning to 0v some 30seconds after ignition is switch off.
Terminal 4 is the red wire gining a constant 12.58v wether ignition is on or off.
Terminal 5 is the black earth wire.
Terminal 6 is an orange wire to/from the computer giving a reading of 0.29v with the ignition but returns to 0v some 10secs after the ignition is switched off but before the timer relay knocks off.
Terminal 7 and 8 are blanked.