Fuel Gauge Problem

[cheezy_munkey]

Hi,

Does anyone know why my fuel gauge always reads full? I took the speedo off tonight but it looks like all the wires are connected. It's pretty annoying as I have to keep a jerry can in the boot all the time.

Oh ps. I know nothing about elecrical stuff so, if you don't mind, keep it dumb .

Thanks

[bmcecosse]

Stuck float? Shorted out cable to the tank? Take the wires off the tank - what does it read now ?

[cheezy_munkey]

Hi there,

How do I get access to the tank wires? Sorry if this sounds stupid. Is it from underneath the car or from the inside?

Thanks

[chesney]

Inside. The sender is in the middle, you will most likely have to lift the wooden shelf and the spare wheel.

[SUE482]

If yours has a gold faced speedo then it is more than likely to be a bad earth connection to the fuel gauge or the sender. Dont leave on for to long because they have been known to burn out.

[cheezy_munkey]

Hi there,

I took the wire off the tank and it still read full. I'll attach a couple of pics. One from inside the boot and the other from behind the speedo. Any ideas??[frame][/frame][frame][/frame]

[SUE482]

From your photos I assume its a gold faced speedo in which case it probably is a bad earth either on the tank or the speedo. I would fit a extra earth wire from the sender to the body so eliminating rusty tank and sender screws, also make sure the two securing screws on the speedo make good contact with the body. (Earth) As I said earlier don’t leave in this fault condition too long.

[cheezy_munkey]

Hi again,

Thanks so much for your help. Can I just check, to earth the sender am I supposed to connect the end of the wire to earth or just somewhere on the circular metal section?

Also, I tried to earth the 2 screws on the back of the fuel gauge. When I earthed only one of them first, the gauge went straight to empty. When I removed the earth, it jumped back to full. I then left that one connected and connected the other earth. This blew the fuse. After replacing the fuse, I then tried to remove the first one and leave the second one only connected. This made no difference at all. Gauge still reading full.

Any ideas?

[bmcecosse]

You're going to start a fire messing about like that....... the only part that should be earthed is the body of the petrol tank.......

[cheezy_munkey]

Cheers. Mr Ecosse.
Did mention at the start that I don't have a clue what i'm doing. Just hoping for some advice from you clever people.
Anyhoo, haven't managed to set it on fire yet which is a bonus but it's still reading full even when I earth the petrol tank or when I disconnect the sender.
Any ideas? I'm determined to know my fuel status.
I'm very stubborn.
Thanks again.
Paul.

[bmcecosse]

Sounds like it may be a break in the cable between the gauge and the sender. I would run a temporary run of cable between the two and see what happens..

[lambrettalad]

good idea

[cheezy_munkey]

Did it. I'm afraid that nothing happened when I did. Gaaaarrrrgh!! this thing's driving me mad now.

For info, it's this speedo ...

...[frame][/frame]

It's still reading full when the ignition's on and empty when it's off.

[tysonn]

Well if the pointer moves it sounds ok.Take out the float its probably stuck in the full position.

[cheezy_munkey]

Thanks. I'll try that.
Another point, is it possible that the sender is not compatible with the gauge? I read a post somewhere else where someone suggested that as a possible problem.
I only bought the car a few months ago and it didn't work when I bought it.
There's a picture of the gauge and the sender further up if anyone knows the compatibility.

[tysonn]

Well if you remove the sender you can move the float and see if the pointer responds.You will at least eliminate one potential cause.

[SUE482]

Hi the photo of your sender suggests that it is not for a Series II, its nothing like mine.[frame][/frame]
If I remember correctly the sender should have a resistance of approx 40 ohms in the empty position and approx 90 on full, yours if its the later one will be 24 to 250 ohms, also I notice rusty screws securing the sender to the tank this is where poor connections arise. Connections on the gauge itself are 3, two terminals and an earth. The two terminals are B which is GREEN connected to -12, T which is BLACK with GREEN stripe connected to the sender and the body of the gauge which is earthed through the two main securing screws on the speedo. Connections to the sender are 2, BLACK with GREEN stripe connected to the only terminal and the body which is earthed through the 6 securing screws and the tank self tapping screws to the body. These earths on the gauge and the sender are most important. If its the later one it is incompatible with the gold faced unit.
DONT MESS ABOUT WITH ELECTRICS AND OPEN PETROL TANKS.

[cheezy_munkey]

Hi Sue,

Thanks for the advice. I think it's looking likely that the sender I have is not compatible with the speedo. I think a previous owner has tried to fix it with the new style sender, it hasn't worked and they've given up. I'm starting to feel like Columbo with all my investigating around this problem.

I'm a bit skint at the moment but I'll maybe look into buying a new sender when the cash is flowing again. I believe it's £40 on ESM for the older model (ouch)!!!

Thanks for your help in trying to get to the bottom of this.

Cheers
Paul.

[SUE482]

No probs if I come across a cheap one I'll snap it up for you.

[cheezy_munkey]

That'd be lovely thanks