I have a 1982 XJ6 Series 3 not starting.
I have Checked everything .
It seems as though the fuel injection main relay is faulty. the question is ,Where is it located?

 

There is no "main relay", but there is a fuel pump relay located on the firewall inside the engine compartment. Please list the tests you have carried out, and their results. The fuel pump relay is supplied with voltage directly when the engine is cranked. Once the engine starts, and the driver returns the ignition key to the 'run' position, this voltage path is switched off and the voltage is supplied via the airflow meter via two small (actually tiny !!) contacts that close when the flap in the AFM moves under air flow.
Fuel injection and the Jaguar XJ6 4.2 Series 3 / AJ6 Engineering

 

have you opened the fuel system to atmosphere? (example: disconnected a fuel line).

If yes, check that the Fuel Cutoff Switch has not tripped. Located on the passenger side in Left Hand Drive cars, at the right corner / end of the dash, above the kick panel. There is a spring button on top of the switch box, press it down, if it clicks it was tripped. If it just springs back, it is fine.

 

On the firewall, almost directly below the engine bay diagonal braces, in a row of four relays.

Starting from the right (viewed from driver's seat) you have: The all-red Diode Pack. This is not actually a relay....but it looks like one. It has several diodes inside and directs the flow of voltage in the fuel pump circuit. Next is the fuel pump relay. Next is the main relay, which feeds the injector ballast, the Air Flow Meter, and the ECU. Furthest inboard is the silver starter relay.

Note: The fuel pump and main relays can be inadvertently reversed in their positions. The fuel pump relay is easily identified by the white/green wires, which are not there on the main relay.

The main relay is easy to check. With the key 'on' you should have 12v + on the brown/slate wire. If not, post back.

Cheers
DD

 

I stand corrected ! Sorry for my error.

 

I have all the correct voltages at the relays , the resistor box for the injectors. when i crank the car the fuel pump runs. the injectors do not click. if i move the airflow flap the pump works and the injectors click once.
i have checked the continuity of
the pulse wire from the coil to the ECU. I have tried 4 different ECUs. I heve checked the diodes in the diode pack. Fuel; is there, spark is there. What next?

 

I have checked for the correct voltage at the relays, the resistor box for the injectors, i have checked for continuity of the pulse wire white/black to terminal 1 on the ECU. i have tried 4 different ECUs
when i move the airflow meter flat ,the fuel pump runs and the injectors click once. fuel is there spark is good. will just not start.

 

I suggest you check the continuity of the other wires from the ECU to the engine, especially to the AFM. It is not uncommon to find a wire break in the engine bay area where they are subject to high temperatures.

 

So the supply via the AFM is good, as you've proved by moving the flap, but on crank this supply is switched-off as the flap doesn't move enough. Therefore you need to check the supply via the ignition key on its "start' position. I believe this has caused problems in the past on a few cars.
Have you tried a bit of 'Easy start' in the inlet trumpet ?

 

At the rear of the water rail is a bundle of black ground wires. These are the grounds for the entire fuel injection system. Make sure they're clean and tight...and none of them are dangling in air.

Cheers
DD

 

I have checked all the earths, everything clean and tight. the impact switch working correctly. pulled all connectors apart and cleaned, sprayed with cleaner.

 

OK, last question - when did the car last start OK ?

 

It was running on Sunday 4th .Switched of normally and parked. Sunday afternoon would not start. Fresh fuel in both tanks, switch over working correctly.

 

I found one bad wire in the engine harness, and the the temp time switch terminals.
I am in South Africa, we don't have the purge cannister, and air switching with associated components.

 

I'm not a Jaguar engine person, but in nick's post he states the injectors do not click but the fuel pump runs in "start" position. I would think the injectors need to click (batch-fire I think) twice per revolution, even when in start mode. Is it possible the key switch can connect 12v to the pump but not the ECM or whatever provides the ground pulse to the injectors? At key "start", is there 12v at all the injectors?

Dave