Hello,

I have seen some threads with fuel sender/gauge indication problems but none with my specific set of circumstances so I am posting with hope that this might help someone in the future and/or someone out there with more experience will head me off at the pass and save me some recon time.

I have a 2002 S-Type 3.0 with 95K miles on it. When the tank is full it claims a 305 mile range. When the gauge gets down close to empty (in the little red 1/16 of a tank area) I have only gone about 200 miles. The fuel computer says it was averaging 18-20-ish MPG and it claims 95-ish miles to empty.

I go to the gas station and it only takes 10-11 gallons before the pump won't pump anymore and it indicates full again. 10 gallons at 20 MPG works out mathematically but everywhere I look the stated capacity of the fuel tank is 18-ish gallons, so there is a miss-indication of 8 gallons or so.

I know about the saddle shaped tank and the two senders that get combined so I am guessing that one sender is malfunctioning in some way. I believe the choices are stuck up, stuck down, stuck mid-travel, a dead short or open/broken connection.

My plan is to drive the tank down to about 3/4, get under the back seat, pop the black caps, unplug the plugs, and put a multi-meter on some pins and shake the car to see if the meter moves.

My questions are:
Any pitfalls? Chances of breaking or burning out something expensive.
Where do I find a pin-out for the plugs? They have 4 pins. I guess that they are two for the pumps and two for the senders. But which are which? Are they the same on both sides?
Am I headed in the wrong direction and I should look elsewhere? (Fuel computer faults or ???)

I will add to this thread (or edit this post if I can) as things gets solved.

As always, any help/advice is much appreciated.
Thanks and be well.

 

N=brown
NU = brown/blue
NR = brown/red
WR= white /red
WU = white/blue

 

dauraf, Thank You. This will help a lot.
John J

 

Sounds like you have a good plan of attack. The complete wiring diagrams are here:

http://www.jagrepair.com/JaguarSType...OBDIIcodes.htm

See figure 07.1 for fuel level sensors, and 03.4 for the fuel pump.

For access, it may be easier to read both sensors from the Rear Electronic Control Module (RECM), behind the liner in the right side of the trunk.

 

kr98664, Excellent info!! Thanks!

 

3/25/2020 UPDATE:
I multi-metered both senders with an analog meter and they both read 120-ish ohms. I couldn't shake the car enough to get the meter to wiggle because it was analog and not very sensitive. (...and I'm not the Hulk) I cleaned the plugs and put them back together and took them apart a couple of times to scrape the contacts and then put the whole thing back together.

I didn't notice any difference right away but since I have driven the tank down to half and the fuel computer is giving me a 150-ish miles to empty, I am cautiously optimistic that the scraping/cleaning did the trick. As soon as I got identical readings that weren't dead short or open circuit I was thinking it was a contact problem and not a hardware failure. I hope I'm right.

I'll drive the tank down to less than a quarter and see what it takes to fill up and decide at that time if this issue is closed. I'll report back here when I have more info.

Thanks for looking.

 

4/5/2020 UPDATE:
I ran the tank down to just less than a quarter and it took just about 10 gallons. I was expecting more but it's better than being almost empty and taking 10 gallons. For now I'll call it good.

Take-aways:
Check the connections first.
Aftermarket parts are probably not going to have wire colors that match the diagrams.

If anything changes I'll post more here.

Thanks for looking. Be well and don't lick any doorknobs.