My mechanic has just redone the head gasket on my 1984 XJ6 Series.
It started ok after the work was complete however the next day it wouldn’t fire up.
My mechanic (Who’s not a Jaguar expert) has run through the list of potential problems and eliminated all the usuals that seem to pop up in these types of non start posts.
He seems to believe that their is no injector pulse and that there is a negative switch issue.
Is there some sort of injector module we should be looking for?
For ‘no injector pulse’ there are several possibilities but I’ll start off with a couple of the easier ones that are likely to have been disturbed during a head gasket job:
At the rear of the water rail is (or should be) a bundle of ground wires. Make sure there are no strays dangling in the breeze and that the connections are secure. These are the grounds for the entire fuel injection system
From the coil “-” post there is a white/black wire running aft along the water rail, Make sure all’s well with this wire. It’s a ‘trigger’ wire for the F.I. system
Others will chime in with more but I’d begin by checking these two first
This is of course on the list of ‘all the usuals’ - but it needs confirmation. As Doug implies; there are several possibilities - and both the ignition and the injectors are triggered by the ign amplifier. ‘Seems to be lack of…’ requires confirmation if already suggested procedures is of no avail…
Ignition may be tested with a spare plug hooked to any plug lead - and ideally lack of injection should be verified with an injector test light. With ign ‘on’ the lamp should be off, - and dim and flicker during cranking. And a test lamp should be connected between the coil neg and ground to generally check ign amp function. With ign ‘on’ the lamp should be fully lit - while cranking, the lamps should dim and flicker…
A secondary injector test is to listen if the injectors are clicking while cranking…
And an overall quicktest is to connect a jump wire between coil pos and batt pos. Just in case the fault is ‘no power’ to the coil from the ign key - an ign key fault…
But it is important to confirm what is actually working and what is not, assumptions are invalid - you may bark up the wrong tree…
Easier said:
If ignition is powered up, the injectors (and the whole injector wiring from the coil to the ECU in the boot back to the injectors) can be checked by unhooking and repeatedly contacting the bullet connector Doug mentioned (water rail). If it clicks then that’s the injectors (all 6) and they are fine.
https://youtu.be/RADE9JMdz40 That’s said cable. Then follow Doug and Frank because they know the car inside out perfectly.