Faulty Fuel Gauge

Anyone tried this(click me) yet? A few years back I had a fuel sender fault where the display was flashing 18.8 gallons all the time no matter how much fuel was in the tank and doing the reset procedure had no effect. Turned out to be a broken wire in the sender unit. The sender unit is simply a long tube with a float inside which moves up and down a central column which has a coiled wire around it. One of the wires to the float had broken on mine. If you very carefully dismantle the unit you can solder the wire back together. The wire is very fragile and it's quite a tricky job but mine has worked perfectly ever since.

Interesting point you make Juzz, I note that you had a reading of 18.8gals when flashing, which could well be the reading of an open circuit sensor. equally I have been able to simulate a Timer Relay failure in my Alp, and get the same 18.8 reading. The reason I dont think it is Martin`s problem, is because he is getting a reading which increased when he put more fuel in which indicates to me that the Sensor is working. However you will see in the last paragraph of my suggestions for Martin to do, I did suggest that as the boot liner will be out, it is an easy chech with a meter, which should eliminate it.
The Sensor of the later Alps is a very simple unit which equates to a variable resistance the value of which changes with fuel level.
I dont know what year your Alp is, or the others in your link, but pre 89/90, the fuel gauge cct is completely different to the later models, and from info Steve D posted some time ago, the early Sensor was around three times more expensive than the later ones which have to use a TSU,
Thanks for your input, all info like this helps in the understanding of these Alpine Electrical ccts, I will remember this one for future reference.

Cheers

John

[BIG_MVS]

Ah no John. Fuel Level did not increase when I put fuel in. It only increased after a reset. Chatting to the "Mr Miyagi" of Alpines has suggested the tank sender so will try that as well as the TSU as you suggest John.

Juzz has an early Alp John so no TSU.

Fuel Level did not increase when I put fuel in. It only increased after a reset.

Yes I understood that Martin, but the fact that it went up at all, even after the reset, and showed a decreasing value as fuel was used subsequently, which I understood you to say, still leads me to believe the sensor is OK...............but I could be wrong .....anyway the resistance check across the sensor will tell all.
Perhaps that test would be worth doing first before unbolting the TSU, as the TSU in my Alp is a pig to unbolt.....even worse trying to get it back
I did guess Juzz, and the others in his link, had early Alps, a they mention a wire being attached to the float.....in ours there is no such wire. The float slides up and down two resistive wires effectively shorting between them, so as it slides up, so the resistance decreases. The two connector pins are directly attached to the top of each resistive wire.



Look foward to hearing your results.

Cheers

John

[BIG_MVS]

Right swapped the sender for my spare still the same(not 100% that was working though to be honest). Then tried each of my 2 TSU's and still the same flashing after 3-4 miles.

I'll try and get turbodog to bring his spare relay he had with him on sunday to try.

1. Right swapped the sender for my spare still the same(not 100% that was working though to be honest).

2. Then tried each of my 2 TSU's and still the same flashing after 3-4 miles.

3. I'll try and get turbodog to bring his spare relay he had with him on sunday to try.

Martin,

1. The sender is very easy to check out of the car....connect a meter switched to ohms across the terminals of the sender, turn the unit upside down....note reading....turn back....note reading.....If readings are between, say, 2 ohms and 86 ohms...unit is OK. (right way up = 86 ohms....upside down about 2 ohms) If you turn it slowly, you will see the readings vary between the two.

2. Do you know if either of them actually works?

3. The check with a meter on volts across the YELLOW and BLACK on the TSU, which I explained before, will prove conclusively if the Timer Relay is working or not

John

Ok, so i'm gong to join in on this one now....

My tank sender has been swapped

My TSU has been tested (Thanks JohnC)

..............and now yesterday my new relay from the steelers sent my readout from a stable misread of 9.6 gallons (and sometimes self reseting) and reducing to 18.6 and flashing.....

What the £$%^ should I do next!!!!

[BIG_MVS]

Scrap it

What happens when you put the old relay back in? Does it go back to 9.6 gallons?

Did they even work from new lol

Mine was giving an indication of roughly how much fuel until I fixed something else and in true atmo style the second you fix one thing another drops straight back off!!! I took it for test drive last week and the fuel gauge instead of flashing a representative reading, it just remained the same, flashing away. Never mind ill drive till the petrol light comes on and I'll top it up with 10 litres of spare fuel I always carry...... just incase .

You guessed it the light did not come on and I ran out of fuel on the run in to Guilford. Luckily it was down hill and there was an exit off the dual carriage way otherwise that would have been dangerous let alone embarrassing.

Has anyone ever fitted an after market gauge and sender ? It can't be worse than a factory fitted one

Just a few more items to fix yet John, along with fifth gear.

Si21

Scrap it

What happens when you put the old relay back in? Does it go back to 9.6 gallons?

Oh yes, back to the same reading!! More nonsense....

My tank sender has been swapped

Jon.....all the info on testing this system is already on this thread so there is no point repeating it, but one thing regarding the above....is the now installed tank sender Pt No. 60 01 018 928?
The other....the new relay....is the design and number exactally the same as the old one?

John

Yep, it gives the same 9.6 gal reading with both senders.....

Yep, it gives the same 9.6 gal reading with both senders.....

.......and the relay?

The new one sends it flashing.....