I ordered a handbook but until that comes in I´ll have to rely on you kind people to answer some basic questions.
First, what is the deal with the fuel tank gauge switch on the dash? I put gas in both tanks. When I press it one way the gauge goes to empty. When I press the gauge the other way it shows half a tank. I assume the gauge is for each tank separately and may not be working for one tank.

Also I´m ordering some parts and I´m being asked if it´s OHC or DOHC and whether it´s a 2 or a 3 in the vin number. I left the car at a shop to be checked out and I have the vin, but which digit in the vin indicates if it´s a 2 or 3 and therefore if it´s OHC or DOHC?

panza
1985 XJ6
1992 XJ40 Sovereign
1993 XJ40 Sovereign
2002 S type 4.0
2004 Lincoln LS
???? next

 

Each tank has its own sending unit, and the wire from each sending unit goes thru the switch and then to the gas gauge itself. Thye gauge seems to be working so I'd say you have one faulty sending unit or a bad switch.

You have a 4.2 litre DOHC engine. There was no single OHC variant. The 8th digit in the VIN should be the engine designator. I never understood the "2" or "3" as seen in many parts listings. They only came one way.

Cheers
DD

 

Thanks again for the help, Doug.

 

Great questions, especially about the fuel tanks. I'm having the same issue.

As always, thanks for the info @Doug!

 

This might be a stupid question, but if I defiantly have gas in one of the tanks that the gauge isn't reading, do I need to push the gauge switch (on the dash) to actually use fuel in that specific tank or will the car automatically switch over once one tank is empty?

 

Yup :-)

Both tanks feed into a single "changeover" valve next to the spare tire. The changeover valve opens the line from one tank and closes the line from the other tank in one motion.

Unused fuel from the engine is routed back to whichever tank you are using at the time. this is accomplished by two "return valves"...one in each rear wheelwell.

Pushing the dashboard button operates all 3 valves at once....and also switches the fuel gauge wiring so that the gauge reads only the tank you are using at the time

Cheers
DD

 

Excellent info...thanks for the clarity Doug!