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Fuel gauge reading wrong


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#1 masters24

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Posted 06 September 2007 - 07:59 AM

Has anyone got any idea why my fuel gauge is reading out incorrectly?
It will read accurately for the first half of the tank, but as soon as I gets lower than 1/2 a tank it starts telling me that the tank is full, or it is 3/4 full, or it is empty... there is definately an issue here, but I called in to see the ford blokes here, and one of them told me to go see and auto elec. So, not sure where the problem lies...
;) LEXI - the XH XR6 lady...:tongue:

#2 rynostation

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Posted 06 September 2007 - 09:53 AM

Has anyone got any idea why my fuel gauge is reading out incorrectly?
It will read accurately for the first half of the tank, but as soon as I gets lower than 1/2 a tank it starts telling me that the tank is full, or it is 3/4 full, or it is empty... there is definately an issue here, but I called in to see the ford blokes here, and one of them told me to go see and auto elec. So, not sure where the problem lies...


get an aftermarket guage and sender installed. its not a big job about 100-130 in parts, probabaly take about 2-3 hourzs to install
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#3 BIGCAV

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Posted 06 September 2007 - 10:48 AM

dunno what it is but its a common ford problem in newer cars. mates ba does it too

c1tb.jpg

 

www.OzFalcon.com.au

 


#4 DaveGod

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Posted 06 September 2007 - 01:59 PM

Lol, my fuel gauage is always on empty, and my odometer doesnt work. I havent run out of fuel yet.
For Show ~ 351 Turbocharged XF S Pack FOR SALE

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#5 geohatrick

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Posted 06 September 2007 - 05:47 PM

lol when my fuel gauge gets to having two red lines left it means if i go up a hill ill run out of petrol lol so i just fill up when it gets to there i dunno why it doesn go all the way down to empty. this is with an xf spac dash in a gl.

Cheers Zac
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#6 Yellxf8

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Posted 06 September 2007 - 06:09 PM

firstly disconnect the wiring loom at the tank. swith on the ignition. the gauge must obviosly read zero if not then the clster unit is cactus. switch off the ignition and reconnect the wiring loom.

put a voltmeter at the sender at the tank at the centre electrical located under the fuel sender cover and the negative to the body of the sender. with the tank full it should read 4.5 volts. if its half full then 2.2 -2.8 volts . if you get these readings but no show at the gauge then the fuel gauge is faulty or the wiring. if you get no voltage whatsoever the the sender unit is buggered. If you have a full tank and the centre post of the wiring loom indicates 4.5 volts or above and the gauge shows less than full then the gauge is cactus.

#7 geohatrick

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Posted 06 September 2007 - 06:22 PM

thanks for that will try it on the weekend.
Cheers Zac
Brown fairlane.... slow & lowered!

#8 Gaz

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Posted 06 September 2007 - 07:56 PM

Do ypu have twin tanks? the puckin wiring on the XH twins is a nightmare.
GARY NOT FUNCTION BEER WELL WITHOUT

#9 masters24

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Posted 06 September 2007 - 10:13 PM

nah, just XR not outback... single tank...
tis confusing me... I am just getting to the stage that i only use 1/2 a tank, then fill it up again...

I will take the tuff liner out before anyone looks at it, or else there is just labour cost that i dont need to pay (fish-oil the tray while it is out too i guess)
;) LEXI - the XH XR6 lady...:tongue:

#10 hefurnahn

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Posted 12 December 2007 - 12:26 AM

As far as I can tell, my fuel gauge is functioning - I tested it by applying a 1.5V battery to the cluster input while the sender was disconnected and it read about 1/4 on the gauge.

With the sender unit connected the gauge needle slaps to full, which is not surprising since the sender output is 5.3V regardless of whether immersed in a 3/4 full tank or removed.

What is my best option for replacing the sender unit? What are the chances of finding a new sender unit? A 2nd-hand sender unit that wont fail 6 months from now? Is there an aftermarket/"non-genuine" product that will fit the bill?

Just out of curiosity, does anyone know or can point me to the technical description of how the sender unit works. I read here somewhere that it uses a semiconductor as opposed to a variable resistor. I removed the bottom of the one I have and found no moving parts inside, which suggests that the unit uses the "admittance" of the fuel to regulate voltage output.

If I had a detailed schematic for the unit I could probably service the one I have or build a replacement board.




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