Fuel gage has been dropping , even though there is pleanty of fuel in the tank. Replaced fuel sender. Today filled up , and gauge dropped to empty. It’s either the wiring or the gauge. What is the best way to check the wiring from the sender to the gauge?

 

Hi Jerry, could you please put the year and model of your Jag in your signature please. We've had folks post in the X308 forums that were actually other models. We want to make sure we provide the correct info for the correct model. Plus, with your question, the fuel sending unit goes in differently on early models.

So, for the gauge, drill a hole in the top of the tank just big enough to put a 3/8" dowel rod in it so you can measure how much fuel you have....oh wait, that was an old tractor....j/k Jerry.

You write as if the gauge reads correctly, but then starts to fall to empty...is this correct? If so, I am more suspect of the dash gauge than the sending unit, because your initially getting a proper reading and its been replaced and doing the same thing.
Do you still have the old unit? If so, meter it to see if it was functioning properly...
For wiring (and many other fix inquiries), you'll want to bookmark this site...JagRepair.com - Jaguar Repair Information Resource
...and from that, here's the electrical diagram for a X308... http://www.jagrepair.com/images/Auto.../jagxj1998.pdf

 

Jaguar issued many TSBs but most are MODEL YEAR or VIN related.

You can help us all out by giving more info about MAKE MODEL YEAR!! (I hate mystery cars)

bob

 

On my 2000 Jaguar Vandenplas: fuel gauge reads full when I fill tank, but drops rapidly to empty after driving about 150 miles. Replaced fuel sending unit, still does the same, just filled up , drove 5 miles, gauge dropped from full to empty, first time that happened . Has to be the wiring or the gauge. Question: How to check the wiring?

 

Hi Jerry,

Thank you for giving us the year and model of your Jaguar.

I have merged your latest post with your original thread. Please do not start any additional threads on this topic - it just creates confusion and duplicated effort on the part of other members who want to help.

Cheers,

Don

 

Don: now if only someone could tell me how to check the wiring.

 

When I was working on ships we use to do all the gauges mainly VDO stuff
but if the temp or oil or fuel was doing funny stuff it was always a resistor, this resistor is used to add to the wiring resistance to set up correct calibration.


From Highorse
http://www.jagrepair.com/images/Auto.../jagxj1998.pdf
Fig.08.1 page 52
shows the wiring however I see no added resistor only the resistance of the sensor.+ wire resistance this is all taken into account by the manufacturers.
1 check the input voltage of (RW)
2 remove the connections to the tank sender unit short / join together RW and BW this is bypassing the tank sender unit and you should get either full tank reading or empty nothing in between ignition on.
that's to test the gauge
3 then plug back in RW to the tank sender and measure the voltage red lead of multimeter connect it to spade connector that the BW is usually plugged on to, and the black lead from the multimeter connect it to a good ground Neg-
that to test the voltage flowing through the sensor would be nice if you can have it out so as to move it up and down.
4 and last of all as the video showed check the change of resistance of the sender, the specs should be around this site or workshop manual somewhere that will give you the resistance range.
all the best Dutchy