Hello every one
I`m hoping some one will be able to shed some light on my problem . I have a 1984 XJ6 4.2 Auto
The car was my daily driver and got laid up for a couple of years . When started using it again , it would cut out , and not restart after about 4 miles of running fine . If you leave it for a few hours , starts fine and drives fine ..
I did a few tests and saw the fuel pressure was dropping . New pump fitted , still same . Fitted new plugs , leads , cap , rotor , ignition module and a new ignition trigger . Still the same . Next step was to put on a dyno to see what was going on ( which I have access to )
Ran the car for almost an hour , no problem , up and down rev range until ...
If you let the engine drop to idle it cuts out and wont re start . The injectors turn off on coast down , but if you let it coast to idle .. the do not kick back in
So my question would be , what turns the injectors back on , after coast down closure ?
Ive have the car since 1992 and this is the first issue ive had with it ( 175000 miles )

 

The ECU turns them back on, after receiving (i) a throttle closed signal from the Throttle Position Sensor and (ii) the revs dropping below a given level (eg 1400 rpm on the V12 HE).

Worth checking the TPS is set correctly, as if not, this might be the trouble, or part of it.

 

Thanks Greg . But the XJ6 does not use a TPS , unlike the XJ12 , just a micro switch which is open or closed and only fitted on autos
But thanks )

 

Fuel blockage due to rust in tanks?

 

And isn't the function of that switch to tell the ECU if the throttle is open-closed? And possibly why your injectors don't switch "on"?

I ask because the USA cars had a different arrangement; I'm not familiar with the specifics of a non-USA set-up

Cheers
DD