Date of issue 07/03 Bulletin Number 310-10 Page 1 of 2
07/03V8 XJ Series
Difficulty Filling Fuel Tank –
Fuel Gauge Not Indicating Full –
Spit Back/Premature Shut Off – Diagnosis
This Technical Bulletin provides information to aid in the diagnosis of customers complaints of
difficulty in filling the fuel tank on vehicles within the above VIN ranges equipped with the
AJ-27 engine management system.
A number of fuel tanks returned under warranty for fuel filling issues, have been found to have
Before replacing the fuel tank for fuel tank filling issues on vehicles in the above VIN ranges,
please carry out the checks outlined below:
• Establish whether the customer issue is a spit back/premature shut off, or the fuel gauge is
not showing full after filling the fuel tank.
• If possible, reproduce the customer issue to verify the concern.
FUEL GAUGE NOT INDICATING FULL
• If the fuel gauge is not indicating full, then measure the fuel sender unit resistance when the
fuel tank has been filled. The resistance should be 80 ohms.
• If incorrect resistance is measured from the fuel sender unit, drain the fuel tank, remove the
fuel sender unit and measure the resistance at full position. The resistance should read 80
ohms and empty 900 ohms. If incorrect resistance is measured, replace the fuel tank sender
SPIT BACK/PREMATURE SHUT-OFF
• Inspect the fuel tank, canister close valve (CCV), and vapor line for damage/restriction or
blockage. Check the fuel vapor pipe from the fuel tank (inside the luggage compartment) for
any signs of damage. Check under the vehicle where the pipe enters the primary carbon
canister, inspect the cross-over pipe from the primary carbon canister to the secondary
carbon canister, and the secondary/canister vent to the CCV, the CCV and pipe to
atmosphere for signs of damage.
• If no fault is found, substitute the carbon canisters and reassess. High-pressure drop across
the carbon canister(s) can be caused by internal damage or saturation of the carbon with
liquid fuel. Substitution will verify this fault.
1999-2003 MY V8 XJ Series
2000-03 MY XJR