Fuel gauge sticking.

Davey1991 · 18th May 2017, 13:46

Afternoon everyone.

This is more of an irritation that i would like to get to the bottom of more than a drastic problem.

Only noticed this morning but it would appear that my fuel gauge will sometimes decide to read constantly full.

The car is sitting at just under 3/4 of a tank and most of the time the gauge reads perfectly normally, this morning it decided to stick on the max level, when i turned the car off and back on it did the same until i removed the key and left the ignition turned off for a couple of minuted and lo and behold it is back to normal.

I thought it was just one of those one of "british" things but it has done it again this afternoon.

Anyone know of anything similar or what the cause could be?

Plenum is bone dry and clear before i get asked.

Cheers everyone.
James.

FLYING BANANA · 18th May 2017, 14:42

It's the sender unit in the tank. Mine plays up, in my 1.8t, when the weather turns hot. Been like it for a couple of years now, Might get around to getting it fixed one day

T-Cut · 18th May 2017, 16:17

Quote:

Originally Posted by Davey1991

- - - my fuel gauge will sometimes decide to read constantly full. - - - Anyone know of anything similar or what the cause could be?

Has any work been done on the tank? A replacement pump for example?
There are two level floats in the tank and the gauge 'adds up' the signals from both. This means a completely FULL readout suggests both rheostats are compromised or their outputs are erratic.

You could check the resistance readings for each rheostat. You need a multimeter and access to the tank harness connector under the rear seat (RHS). These are the typical results.

Sticking floats are typically caused by the arm fouling on something after being replaced incorrectly. They seem to be very sensitive to misalignment. If you attempt a fix, be aware it can make things worse. But there are HowTos on gaining access and what you may find find.

TC

Davey1991 · 19th May 2017, 08:55

There hasn't been any work done in or around the tank in my ownership, many thanks for the diagram, its behaving itself at the moment but i will be sorting it if it becomes a more regular occurrence.

18th May 2017, 13:46	#1
Davey1991 Avid contributor MG ZT Join Date: Sep 2016 Location: Bingham, Nottingham. Posts: 240 Thanks: 66 Thanked 39 Times in 28 Posts	Fuel gauge sticking mk2 cdti. Afternoon everyone. This is more of an irritation that i would like to get to the bottom of more than a drastic problem. Only noticed this morning but it would appear that my fuel gauge will sometimes decide to read constantly full. The car is sitting at just under 3/4 of a tank and most of the time the gauge reads perfectly normally, this morning it decided to stick on the max level, when i turned the car off and back on it did the same until i removed the key and left the ignition turned off for a couple of minuted and lo and behold it is back to normal. I thought it was just one of those one of "british" things but it has done it again this afternoon. Anyone know of anything similar or what the cause could be? Plenum is bone dry and clear before i get asked. Cheers everyone. James. Last edited by Davey1991; 18th May 2017 at 14:25..

18th May 2017, 14:42	#2
FLYING BANANA Moderator/Club Shop MG ZT 1.8t+. No.3 of 4 in Sunspot Yellow & Ford Fiesta in Black. Join Date: Aug 2010 Location: Rattler Farm Posts: 22,624 Thanks: 9,270 Thanked 15,645 Times in 6,806 Posts	It's the sender unit in the tank. Mine plays up, in my 1.8t, when the weather turns hot. Been like it for a couple of years now, Might get around to getting it fixed one day __________________ 233,730 onen hag oll

19th May 2017, 08:55	#4
Davey1991 Avid contributor MG ZT Join Date: Sep 2016 Location: Bingham, Nottingham. Posts: 240 Thanks: 66 Thanked 39 Times in 28 Posts	There hasn't been any work done in or around the tank in my ownership, many thanks for the diagram, its behaving itself at the moment but i will be sorting it if it becomes a more regular occurrence.