I just bought my first car... 1981 XJ6... car runs good and looks good but i have few problems with fuels comsumption... it eats too much gas... i did everything i can including cleaing the battery post...and i know its not a leak...
than how come my fuel level drops when i let my car sit overnight?
also
my left tank was full while right one was empty... when i drove few times... the gauge shows both sides at half... is that normal?
is there any other problems i should know about with this car?

Submitted by SC20-30420CJ on Wed, 11/26/2003 - 10:08

Hi Gene,
Fuel transferring from one tank to the other is caused by a sticking fuel changeover valve. On a ser3, there are three valves in the system which operate when you push the fuel tank switch on the instrument panel. There is a fuel changeover valve and two fuel return valves. The changeover valve is located in the trunk (boot) just back from the spare tire. If you remove the tire and the plywood trunk panel screwed in behind it, you can see into the rear part of the trunk. There is a fuel pump, fuel supply lines and the change over valve. From the pump inlet, go up stream (follow the big hose) and you'll come to the valve. You can buy them from most of the usual suppliers and replace it yourself. It can be a messy job and fuel will leak out so take the proper precautions.

The return valves are located in each wheel well. There is a panel with two screws and a large bolt. Remove the wheels to see them. The bolt is an irs mounting bolt and goes all the way through the frame support. You don't have to remove it. You can access the valves by just removing the two screws and bending the panel out of the way. If these valves stick, fuel will return to the wrong tank when the engine is running causing the fuel gauge to decrease rapidly (while the other side is increasing!) The return valves are handed, i.e., they aren't interchangeable from left to right. It's not necessary, but I ususlly make it a practice to replace all three valves at the same time when any one shows signs of sticking.
John Testrake
Jaguar Association of Greater St. Louis