Dash Fuel Gauge Indicator

[Rissy]

...Hey there all.

I successfully brought LEX down from Edinburgh to Rugby yesterday (very pleased - especially since I have no AA or RAC or Green Flag cover right now, so was "flying by the seat of my pants!")

Anyway, the journey wasn't 100% without hitch.

1. The Odometer Trip reading, when it naturally rolled round to the 000(0) mark (since I NEVER trip it to ZERO manually due to a bust reset stalk on the dash) it got stuck! Only the (0) rotated round from 0-9 and instead of incrementing the next number, they all stayed indicating 000. After about 40-60 miles (since I wasn't watching it all the time) it then recovered and started rotating as normal again. I'll now have to wait until it hits 999(9) again to see what it does on the next rotation....?

2. I filled up with an additional £30 of fuel about 2/3 of the way down (since I can't get the full distance (325 miles) on one tank) When I did, this took the Fuel Indication back up from very low, nearly empty, to half way again. BUT, after driving the rest of the journey, roughly another 100-120 miles, by the time I got to Rugby, the Fuel indication was still reading about 1/2!? I'm heavily suspecting something has gotten stuck somewhere, and now, i'm really not sure how much fuel is in the tank!!

So regarding 2.

4 Questions.

1. Anyway of testing what it is that has gotten stuck, if anything!? (maybe something isn't stuck, but instead, broken?)
2. Does this happen often to the cars? - Anyone else had this?
3. Any way of freeing anything up to get it working again?
4. Does the "LOW FUEL" indication lamp on the dash (the yellow one) work independently of the gauge? meaning I still have SOMETHING for indication...? Or are they linked, meaning I'm really stuck until I get the issue resolved (besides constantly refuelling, and using rough judgement for estimating the remaining fuel in the tank)

[bjbrownie]

My fuel gauge works fine on start up, but within 10-20 minutes of normal driving drops off to zero-I removed the fuel sender last year and cleaned it up, all the terminals were covered in crud but inside the tank it was clean, it seemed to work every time till a month or so later, but you get used to it. I trust the low fuel light, if it flickers on a few times I start thinking about fuel-with the trip zeroed I get around 27-32 miles for every £10 I put in, and work out how far I need to go with petrol.
The Delorean fuel gauge was never reliable, but I havn't run out yet! 8) :lol:

[Rissy]

...So the Low Fuel Indication light works independently from the sender for the analogue indication then?

Is the sender easy to remove from the tank without, for instance, removing the tank from the car!?

The fuel indication, as crap as it's always been, has always worked for me. This is the first case I've known of the thing getting stuck. (I'm presuming its stuck!)

[bjbrownie]

Pop the bonnet (easy bit) and take the spare out-carefully try to remove the cross head screws that secure the large panel to the bulkhead at the back of the wheel well, a few may just spin around in the captive riv-nut if you're unlucky, remove the panel and the sender units in front of you with 3 electric wires going to it.
Remove the wires carefully, and unscrew the retaining ring anti clockwise, it may be tight so grips may have to be used. Pull out and have a rag or container to catch the petrol that drips out of it.
Clean the connections/connectors and the seal that goes under it (important its not damaged 'cos it will leak petrol and fumes).
Not a difficult job but put covers on your wings to avoid scratches as you lean into the boot area. 8) :lol:

[Guinney1971]

#2292's original factory sender would never read over 3/4 full, even when the tank was brimmed, so
I bought a 'improved' Houston one in 2003 - what a POS it is, its more random then the original one
and you might as well not have it.

My 'idiot light' has never worked either, but I'm guessing thats just a bulb.

When I've done work in that part of the car before, I used to sit x-legged in the front luggage area or
kneel down in it as it made access to all the fuely bits alot easier.

[stunned_monkey]

Chris, you have one of the very first Houston sender units. James Espey brought it over for me in his luggage literally days after they first got them in.

People moan about them but they do tell you what you need to know - when you'll need to fill up, and they do work consistently. At least, that was my experience the whole time I had it (20k+ miles). That trip reset pin has been broken since I bought the car. On 3352 the reset pin works but resets to 009, go figure.

[Martyn]

As for mine........... :roll:

[Rissy]

stunned_monkey Wrote:Chris, you have one of the very first Houston sender units. James Espey brought it over for me in his luggage literally days after they first got them in.

People moan about them but they do tell you what you need to know - when you'll need to fill up, and they do work consistently. At least, that was my experience the whole time I had it (20k+ miles). That trip reset pin has been broken since I bought the car. On 3352 the reset pin works but resets to 009, go figure.

...so what exactly does that mean? The fuel meter reading on the dash is stuck at half way. I KNOW I don't have that much fuel in the tank!

[Rissy]

...Would you suggest this is the dash gauge which is stuck then? Or is there still a possibility that it's dirty contacts not conducting and in fact leaving the gauge at the last known correctly monitored position?

I'm planning on taking a look see tonight after work, so i'll be able to see the condition of the contacts first of all, and if all appears to be ok, then i'm presuming its easier to remove the sender from the tank to check that to make sure the float is not stuck on its shaft, than it is to start to check the circuitry or even dismantle the dash binnacle?

stunned_monkey Wrote:On 3352 the reset pin works but resets to 009, go figure.

This sounds as though someone has had the unit apart, and fiddled with the odometer reset numbers during this time, not realising that the trip position mechanism has been left in the incorrect position to correctly spin that particular column back to the zero mark...

[Rissy]

....I'm still looking for an answer to know if the lamp and the gauge position are linked, or independent? If the sender is stuck, does this stop the warning lamp from working too? i.e. NO indication at all!

A quick answer to save me looking out the circuit diagrams and checking myself...?

[stunned_monkey]

I'd be very surprised if the sender had got stuck because it does not have a sliding contact like the original but uses a magnet and a series of reed switches. Also Lex hasn't been left to stand for any length of time since getting a brand new tank in 2001.

It's more likely to be a dodgy connection although for it to stop moving rather then point skywards would require a drop in power supply to the gauge rather than the connections to the sender itself. This means the light should still work and you can test simply by pulling the sender out and letting it drain. NB the early units can be a challenge to lock back down again.

The speedometer in 3352 had never been removed before I took it out.

[Rissy]

stunned_monkey Wrote:I'd be very surprised if the sender had got stuck because it does not have a sliding contact like the original but uses a magnet and a series of reed switches. Also Lex hasn't been left to stand for any length of time since getting a brand new tank in 2001.

LEX has been standing more over the last 3 years (garaged 11.5 months of the year - not all at once of course). Due to my work commitments, which I'm changing now. Granted it's not 20-30yrs, but I wonder if this is still enough to cause some small issues here and there.

stunned_monkey Wrote:It's more likely to be a dodgy connection although for it to stop moving rather then point skywards would require a drop in power supply to the gauge rather than the connections to the sender itself. This means the light should still work and you can test simply by pulling the sender out and letting it drain. NB the early units can be a challenge to lock back down again.

Does the power loop through the sender and back to the gauge? meaning that a dodgy connection at the sender, heading back to the gauge, COULD be to blame?
(You can tell i'm not happy leaving it not working :lol: )

So even if the power is not getting to the gauge, if I pull the sender out of the tank, let all the fuel drain out, then the warning lamp should still come on? (local normally open contact in there somewhere?)

[stunned_monkey]

No, the power supply does not loop through the sender, yes the light will work if you let the float move to the bottom of the sender by removing it and letting it drain. Or you can simply short the wires, see the wiring diagram, it really is incredibly useful to familiarise yourself with it. Sorry for abbreviated replies, I'm posting from my blacberry. Way better than an iPhone but still limited!

[Rissy]

Ok, I think I'm sorted now. Manky contacts. The sender seems to be working ok. Light comes on at empty, and depending on physical orientation out of tank, it makes the gauge move accordingly. So the dash gauge is ok too. Cleaned up the contacts and now I seem to be showing a more realistic fuel level. Happy chappy. :-)

...now back to my coolant leak! ;-)