The fuel guage on my BX diesel now seems to have a mind of its own. Usually goes mad on a tank refil and then after a while it settles down, sometimes.
Is this a common problem? Can it be easily fixed or should i not bother with it? It does register the amount of fuel left but the lever wont stay still for long.
Andy
Fuel guage gone mad
-
electrokid
- 1K Away
- Posts: 1764
- Joined: Fri May 09, 2008 2:14 pm
- Location: Woking
When it's 'going mad' what exactly is it doing ?
Sounds to me as if you have an intermittant short or open circuit either in the wiring, the sender in the tank, or at the gauge itself.
I recently did some checks on a 16i fuel gauge - the diesel is probably the same or very similar. The sender is effectively a variable resistance with the following characteristics...
GAUGE READING RESISTANCE
Bottom of 'red' 840?
Top of 'red' 300?
Red 'R' mark 240?
1/4 full 170?
1/2 full 120?
3/4 full 60?
Middle of 'full' bar 10?
Top end of 'full' bar 0?
The switch to operate the 'reserve tank' light is separate from the resistance.
So if your gauge is going mad by flicking up to full then back to 'normal reading' there's probably an intermittant short between the wire that goes from the tank resistance to the gauge and the bodywork somewhere - look under the rear seat where the sensor wiring runs from the fuel tank.
If the gauge is flicking down to 'empty' then back to normal reading then you're likely to have an intermittant break in the same wire.
To check which wire is which on the gauge wiring go to the sender under the back seat and short each of the 2 wires in turn to chassis - one should switch on the red warning light and the other should send the gauge to a 'full' reading.
If that doesn't work - drive to Woking and I'll have a look at it - or PM Citronut who is in your area
Sounds to me as if you have an intermittant short or open circuit either in the wiring, the sender in the tank, or at the gauge itself.
I recently did some checks on a 16i fuel gauge - the diesel is probably the same or very similar. The sender is effectively a variable resistance with the following characteristics...
GAUGE READING RESISTANCE
Bottom of 'red' 840?
Top of 'red' 300?
Red 'R' mark 240?
1/4 full 170?
1/2 full 120?
3/4 full 60?
Middle of 'full' bar 10?
Top end of 'full' bar 0?
The switch to operate the 'reserve tank' light is separate from the resistance.
So if your gauge is going mad by flicking up to full then back to 'normal reading' there's probably an intermittant short between the wire that goes from the tank resistance to the gauge and the bodywork somewhere - look under the rear seat where the sensor wiring runs from the fuel tank.
If the gauge is flicking down to 'empty' then back to normal reading then you're likely to have an intermittant break in the same wire.
To check which wire is which on the gauge wiring go to the sender under the back seat and short each of the 2 wires in turn to chassis - one should switch on the red warning light and the other should send the gauge to a 'full' reading.
If that doesn't work - drive to Woking and I'll have a look at it - or PM Citronut who is in your area
1992 BX19 TGD estate 228K Rusty - SORNed
2002 C5 HDi SX estate
2002 C5 HDi SX estate