Good morning guys my name is James and I am in the process of rebuilding a 1985 Jaguar xj12 I have spark I have compression but I'm having an issue with the fuel injectors pushing fuel any hints would be welcome I've changed the main module on the front the fuel pump pushes fuel to the rail but the injectors are not pushing fuel out

 

put 12v to the injector and listen if they click. Should be audible.

If they click then they may not bet getting signal from the ECM. Check the trigger board in the distributor.

If no click, remove the injector and soak the tips in carb cleaner for new hours. Then see if they click, if not, remove the pintle cover and exercise the pintle to see if you can free it up. Chances are the pintle covers willl break. Once you get 12 injectors to function, replacement or your own send them out for a good cleaning.

 

The 'could be' list is long.

One common problem is the very thin, white 'trigger' wire from the ignition module. The 'dreaded shielded wire'. It is encased in a black sheathing and woven ground...looks like antenna 'coax' cable.

Make sure the wire isn't broken, split, etc. Go back several inches in the loom to be sure.

After that use a test light/meter to make sure you have 12v at the injectors with the key 'on'.

Lots of tips/info in the archives, especially from the XJS section.

Cheers
DD

 

Thank you guys for the great tips going to pick up a new trigger unit for it today

 

Doug thank you for the tip I found that dreaded wire but not sure where it goes as it was disconnected and no connectors at the end does it go to the module

 

Assuming no modifications have been made before you came to the car, that little white wire is all that stands between you getting the injectors to work or not. The injection "ECU" receives a pulse via this wire from the ignition system and then uses that to send out pulses to the injectors. Actually this is not totally correct as what it really does is ground the injectors that have a continuous 12v applied to them. The length of the grounding time varies the length of the "pulse". The whole system is analogue, as digital combined injection/ignition ECUs were not then invented. The system is called D-Jetronic. The six cylinder cars were equipped with a later Bosch development called L-Jetronic.

 

Changed the trigger unit and found the third wire thank you guys for all your help

 

Send those fuel. inj. out to be cleaned.

Send me an e mail for addresses , it makes a world of difference to start with clean inj.

walter​​​​​​​