Quick run down of the car, I got given an '85 XJ6 Sovereign for free due to the fact it was rusted out and not running.


I have 3 MK2 Jag's and I planned possibly using some parts from this car, like subframes, maybe driveline etc


So my first job was to get it running again, it was dual fuel and ran out of gas one day and never started again. After realizing one fuel tank was completely rusted out, I bypassed that tank, deleted the return setup to it and feed to the fuel pump, opened up the bypass valves, fitted a new fuel pump as the old one was seized, new filter, cleaned out the good tank, and got it started.


It would fire up and idle on either gas or petrol after that, but nothing more, any load and it would die, so I started eliminating possible faults bit my bit, new plugs, checked the leads, and other basic stuff, deleted the air injection system, deleted and plugged the EGR setup, removed the whole A/C system; its amazing how much extra room there is with those three items gone.


Fixed a lot of the vacuum lines, deleted the HVAC, air injection, fuel purge setup, thermo temp switch, cruise, leaving just dizzy, Idle control valve, fuel pressure reg.


Next I removed the inlet manifold, because the injectors were clogged up from rust from the tank, and also there was a slight coolant leak I wanted to fix, so I removed the inlet, cleaned everything up, set the throttle plate gap, looped the heater core hoses, just kept eliminating and tidying up as I went along.


NOW here is where I shot myself in the foot, there was some sort of alarm system half wired in along with the gas system also wired in, both these were done with wire twists, barely any solder, and the electrical tape had long since gone rock hard and brittle.


So tracing what went where, I eliminated the alarm system that was already half unplugged, removed the gas setup which was wired into the three main relays, when you activated the gas/fuel switch it turned off the fuel pump.


Chasing the alarm system setup, I stripped the interior, the carpet was all wet from firewall leaks, etc, so with the dash removed, I then stripped the rest, HVAC, A/C, heater core and fans, now I have plenty of room to work with.


So with it all buttoned up, I went to start it, and it cranked but not much else.


With the ECU wiring diagram and body loom diagrams, I started the fun process of eliminating faults.


I have the fuel pump now working as it should, the white with green trace wire, gets 12volts, for some reason this wire joins up in a loom that controls all the door switches from the centre console, I eliminated the rollover switch, getting a complete circuit on the white wire from ign barrel to the relays, as the wiring on this car is a headache, while every large component is removed, I have kept all the wiring, apart from stuff I can see only went straight from a plug to a control, like wipers/blinkers/HVAC


The issue i'm having now is no spark.


The battery is 12.5-13V freshly charged (have a jump pack on hand too)


I'm getting 12volts to the coil, 12volts out from the coil to the amp, but also the part I know is wrong, is that I have 12volts going to the coolant temp sensor green wire, 8volts going to the white wire that joins the relays, all the wires that come from the front corner of the engine bay off the 6pin connector, that do oil pressure, alt warning light, ign coil, coolant temp have power, I stripped that wiring as it was all rock hard, inspected and separated each wire, fixed some brittle parts and new female/male joins on the ends, the issue is coming from further in the loom, obviously having 8v in one wire and 12v in the coolant wire means something isn't right.
I have redone a few earths as well.


So now I have to trace that loom to wherever it goes and go from there.


The question I want to know is, how much of the wiring in the car can be deleted if I just want the car to be drivable, without lights, windows, etc, I can see the ecu wiring loom is a braided sheath over it different from the rest of the body looms so that is evident, how much can I delete to just make it a simple setup, I don't care right now about gauges, warning lights (ok oil pressure is handy).


Also I'm assuming that while it ran before, albeit terribly, the horrid AFM still works and the ign amplifier does too, both were removed and refitted, with wires unplugged etc, so could it be possible they have died.


The AFM needs replacing I know that much, due to gas inlet backfires having bent the vane door, but it still ran like that.


Long winded post, and I can put some pics up to show to horror of it all shortly

 

Wow You've done alot of wiring crap. Could the leaking firewall and faulty wiring have caused the ecm to go haywire?
I feel for you, wiring really sucks.

 

The ECU is in the boot (trunk), I've removed it from there and checked it over, but cant see that being the issue as it sort of ran before I went overboard with the strip down.


Would no ECU power, prevent the ignition from sparking?


I'm certain the fault is in the relays not getting power, just got to check over it again with a second person cycling the ignition, and cranking it while I run a multimeter over all the relays.


It has to be just something unplugged somewhere, but I made sure to redo what I've unplugged.


If the motor didn't have great even compression across all cylinders I probably wouldn't even bother, and just keep the subframes and scrap the rest.


Already gutted so much of the car to the bin.

 

An ECU can do thousands of random things. But I was thinking it was under the glovebox like mine. When you mentioned the firewall leak I thought maybe ECU. In the boot a whole other story, but I have seen ecu's go haywire from electical shorts. I am not thinking that about yours anymore. Freakin electrical crap!
You have done so much. I would have a few beers and guess while I was staring at it and have another beer then go to this site and ask someone. this site is great, knowlegable brains for sure. if your patient someone will give you the right advice.
Can you just hotwire the coil straight to the battery? I'm not sure right now, it's dark outside here and I'm beat from a long hot two day venture. So I'm not in the mood to go out and look. I'm not even sure there is the little sender in the distributor to accomplish that idea. I will look tomorrow, but I've never heard anyone mention it on here so it might not be possible.
Good compression!!! don't give up!!

 

The coil is getting 12volts, but I'm sure there is a back feed coming from the connector that is on the RHS firewall that then goes into the wiring loom behind the dash (RHD car)


Chasing that will be my next task I think.


The amount of butt splice joins i've found in this wiring loom is scary, hacked loom for gas, hacked loom for alarm/immobilizer, both I have deleted and chased the wires so they make a full circuit again.


Just need more Jack Daniels and some patience

 

I've electric issues of my own. And looking more and more like I caused them.


Ideas:


1. Lay off the booze while working. After is desirable, as a reward for your toils.


2. Get a wire schematic for that car.


3. The ignition system should provide spark at he right time and in the right sequence sans any activity of the ECM.


4. The ECM does at least two things. Each interrelated. Provide a fuel map. Fire the injectors.


5. The ECM is reasonably safe in the boot. But, the long harness from rear to front, not so much, especialy in a "leaky" car!!


Carl

 

The booze is always after, never during, learnt the two don't mix well a long time ago, you might think you're getting work done, but it takes longer to clean up.


I've got the wiring schematics, both ECU and body, it's certainly helped an immense amount.


I'm ruling out the ECU for now, purely because I don't have spark but I do have fuel, i'll put a noid light on the injectors to see if that side of things is working next time i'm at it.


When I saw there was rust, there is plenty of it, but where it leaked hasn't been too much of a concern, sure the footwells get damp in a decent pour, and the car needs a good airing out, but the wiring looms are in tact.


This isn't my first rodeo, I'm just not sure I like the new bull.


I'm almost tempted to rewire and delete the three relays for something a whole lot simpler, or at least run new power and signal wires.


I'll be eliminating the body loom as well that ties into the same looms the ECU signal wires use, there might be a wire rub somewhere, im saying that because no wire should have an 8v signal, when the rest around it, have 12v. Maybe its the body firewall connector shorting out.