11 replies to this topic

[TheJack]

So my fuel gauge has been working fine but now suddenly it shots right up over a fuel tank and stays there, I guess it might be something to do with the sensor in the tank? Any ideas?

[TheJack]

So my fuel gauge has been working fine but now suddenly it shots right up over a fuel tank and stays there, I guess it might be something to do with the sensor in the tank? Any ideas?

a full tank*

[Kieranlee999]

check the connectors on the petrol tank one might have fallen off mine has done that a couple of times :) 

[TheJack]

The connectors are on good, I have unplugged to see if the gauge dropped and it did, it maybe the floater...it isn't floating on the fuel it's kind of sank :/

[Kieranlee999]

The connectors are on good, I have unplugged to see if the gauge dropped and it did, it maybe the floater...it isn't floating on the fuel it's kind of sank :/

might need a new unit then not sure its not my area someone will be along soon to help

[Kieranlee999]

i think one of these is what you need if its stopped

 

http://minispares.co...px|Back to shop

[TheJack]

i think one of these is what you need if its stopped

 

http://minispares.co...px|Back to shop

Yeah I guess it's what I need haha, cheers for the help :)

[TheJack]

Just wondered but if it is going way over a full tank then would that still be something to do with the sender, also I don't know if the floater is float as it's at a funny angle to look at it, I was looking at something else not the floater haha

[dklawson]

If you unplug the green/black wire at the sender and the needle drops from full to empty, that says there is an internal short of the sending unit.  That is not the common failure mode but it is possible. 

 

However, there is another possibility.  Did you perhaps bump both wires off the sender and put them back on without looking at the sending unit carefully?  The green/black wire goes on the terminal that has a plastic insulator between it and the sending unit flange (look carefully at the picture in the link posted by Kieranlee999 and you'll see a white plastic insulator on one sender terminal).  The black wire goes to the terminal spot welded directly to the flange.  If you swap the two wires and connect green/black to the spot welded terminal it will always read full.

[TheJack]

If you unplug the green/black wire at the sender and the needle drops from full to empty, that says there is an internal short of the sending unit.  That is not the common failure mode but it is possible. 

 

However, there is another possibility.  Did you perhaps bump both wires off the sender and put them back on without looking at the sending unit carefully?  The green/black wire goes on the terminal that has a plastic insulator between it and the sending unit flange (look carefully at the picture in the link posted by Kieranlee999 and you'll see a white plastic insulator on one sender terminal).  The black wire goes to the terminal spot welded directly to the flange.  If you swap the two wires and connect green/black to the spot welded terminal it will always read full.

The cables are on the right terminals, so from what you have said it must be the sender unit?

[dklawson]

The cables are on the right terminals, so from what you have said it must be the sender unit? 

 

For sanity do one or two more checks before spending money.  With the ignition switch in the run position, unplug the green/black wire from the sending unit.  The gauge should drop to below empty.  Touch the terminal on the green/black wire to the black wire terminal on the sending unit.  The gauge should go to full.  That confirms the gauge is working properly.

 

Now remove the tank filler cap and shine a light inside.  Look for the sending unit float.  Look at the shape of the arm of the sender in your tank and compare it to the sender shown in the Mini Spares link above.  After about 1992 (others will need to correct me) the float arm shape is different and requires a Z-bend.  Cars before that have the more-or-less straight float arm shown in the link above.  If your car has the wrong shape sending unit float arm it could be binding.  Make sure if you buy a new sender that is correct for the age of your car.

[TheJack]

The cables are on the right terminals, so from what you have said it must be the sender unit?

 
For sanity do one or two more checks before spending money.  With the ignition switch in the run position, unplug the green/black wire from the sending unit.  The gauge should drop to below empty.  Touch the terminal on the green/black wire to the black wire terminal on the sending unit.  The gauge should go to full.  That confirms the gauge is working properly.
 
Now remove the tank filler cap and shine a light inside.  Look for the sending unit float.  Look at the shape of the arm of the sender in your tank and compare it to the sender shown in the Mini Spares link above.  After about 1992 (others will need to correct me) the float arm shape is different and requires a Z-bend.  Cars before that have the more-or-less straight float arm shown in the link above.  If your car has the wrong shape sending unit float arm it could be binding.  Make sure if you buy a new sender that is correct for the age of your car.

I have figured out the problem, the screw in the back of the clock was loose giving a bad earth, but thanks for your help! :)