XJ12 Non starter
#21
02-24-2019, 11:26 AM
I believe that so far no one has mentioned a particular "no start" cause on the Series III V12 cars: that lovely soft pinkish wire in the engine V that goes to the pick-up in the distributor. It is a favourite snack of rodents and a frequent cause of the failure-to-procede. It is hidden by the cruise control bellows and therefore is not obvious for examination but I have found this to be the issue on several V12 cars. And in one rare case the problem was with the pick-up itself in the distributor.
#22
02-27-2019, 01:22 PM
Today I removed injectors as A2 injector was filling the cylinder with fuel and pouring out of the throttle body
I turned the ignition on and after wiggling the plug for harness and all injectors where firing as they should refitted the injectors and nothing
checked loom again and found two wires rubbed through so repaired those and tried again NOTHING
Then broke a wire on the plug to resistor pack
injector A2 and B4 iirc and possibly 2 others (but can’t see) are firing sequentially but non of the others now
should I replace resistor pack?
I turned the ignition on and after wiggling the plug for harness and all injectors where firing as they should refitted the injectors and nothing
checked loom again and found two wires rubbed through so repaired those and tried again NOTHING
Then broke a wire on the plug to resistor pack
injector A2 and B4 iirc and possibly 2 others (but can’t see) are firing sequentially but non of the others now
should I replace resistor pack?
#23
02-27-2019, 08:42 PM
That EFI loom is past its use by date.
The injectors are triggered in 4 banks of 3.
1A, 3A, 5A
2A, 4A, 6A
1B, 3B, 5B
2B, 4B, 6B
If they are spraying fuel WITHOUT throttle pedal, and/or TPS movement, you do have a wiring issue, and as mentioned that EFI loom down in the "V" is the cause in 99.9% of cases.
The resistor has NO moving parts, and I have never had a dud unit. The plug, and its wires are part of the EFI loom.
The injectors are triggered in 4 banks of 3.
1A, 3A, 5A
2A, 4A, 6A
1B, 3B, 5B
2B, 4B, 6B
If they are spraying fuel WITHOUT throttle pedal, and/or TPS movement, you do have a wiring issue, and as mentioned that EFI loom down in the "V" is the cause in 99.9% of cases.
The resistor has NO moving parts, and I have never had a dud unit. The plug, and its wires are part of the EFI loom.
#24
02-28-2019, 07:23 AM
Today I removed injectors as A2 injector was filling the cylinder with fuel and pouring out of the throttle body
Thats an awful lot of fuel to fill that cylinder, and the ram tube, and then the Plenum floor before it runs out the throttle body. I am thinking the A Bank FPR is ruptured, COMMON, and it can be deleted, lots of info on here about how to, or I have a write on that if you want it. The B Bank FPR is the actual rail pressure regulator, NOT the A Bank unit, it was a "pulse damper" and reeked havoc mostly.
I turned the ignition on and after wiggling the plug for harness and all injectors where firing as they should refitted the injectors and nothing
checked loom again and found two wires rubbed through so repaired those and tried again NOTHING
There will be many internal issues with that loom, and you will see that when its removed and unwound, age again is against those wires.
Then broke a wire on the plug to resistor pack
injector A2 and B4 iirc and possibly 2 others (but can’t see) are firing sequentially but non of the others now
should I replace resistor pack?
Thats an awful lot of fuel to fill that cylinder, and the ram tube, and then the Plenum floor before it runs out the throttle body. I am thinking the A Bank FPR is ruptured, COMMON, and it can be deleted, lots of info on here about how to, or I have a write on that if you want it. The B Bank FPR is the actual rail pressure regulator, NOT the A Bank unit, it was a "pulse damper" and reeked havoc mostly.
I turned the ignition on and after wiggling the plug for harness and all injectors where firing as they should refitted the injectors and nothing
checked loom again and found two wires rubbed through so repaired those and tried again NOTHING
There will be many internal issues with that loom, and you will see that when its removed and unwound, age again is against those wires.
Then broke a wire on the plug to resistor pack
injector A2 and B4 iirc and possibly 2 others (but can’t see) are firing sequentially but non of the others now
should I replace resistor pack?
#25
02-28-2019, 03:59 PM
Thanks Grant
injector A2 was constantly filling whilst pump was running constant with ignition on perhaps valves where closed and filling head/inlet quicker
I’ve removed rail and started removing injector wiring but 11mm bolt holding me up under vac unit of dizzy, I’ll sort that tomorrow and I’ll remove wiring tape and check it out
probably will buy 12 new injector plugs and wire and make my own loom
injector A2 was constantly filling whilst pump was running constant with ignition on perhaps valves where closed and filling head/inlet quicker
I’ve removed rail and started removing injector wiring but 11mm bolt holding me up under vac unit of dizzy, I’ll sort that tomorrow and I’ll remove wiring tape and check it out
probably will buy 12 new injector plugs and wire and make my own loom
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#26
02-28-2019, 09:20 PM
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#27
02-28-2019, 09:40 PM
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I suggesting positioning your new loom alongside the fuel rail.....or anywhere except clamped to the floor of the "vee".
I'd also suggesting "doing the vee". This is a bit of jag V12 slang for tackling many issues at once.
-Remove intake manfolds to replace cam cover gaskets and half-moon seal
-Replace injector harness
-Replace vacuum hoses
-Repair/replace other wiring as needed
-Replace spark plugs and wires
-Check/replace vacuum advance capsule
-Repair centrifugal advance
-Adjust throttles and linkages, replace linkage bushings
-Replace oil switches, if leaking
-Reseal cruise control bellows
-Replace all fuel hoses-injectors, feeds, returns
-Probably other things I've forgotten
These repairs are MUCH easier with the intake manifolds removed and virtually every old Jag V12 needs most or all of them performed. It's a big job but perfectly DIY-able if you just work slowly and carefully. Very satisfying and, in the end, much easier than tackling these repairs on the alá carte approach.
Do it all, do it right, do it once.
Cheers
DD
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Grant Francis (02-28-2019)
#28
03-01-2019, 01:41 PM
As many do.
I suggesting positioning your new loom alongside the fuel rail.....or anywhere except clamped to the floor of the "vee".
I'd also suggesting "doing the vee". This is a bit of jag V12 slang for tackling many issues at once.
-Remove intake manfolds to replace cam cover gaskets and half-moon seal no leaks so not going to touch anything
-Replace injector harness my next move
-Replace vacuum hoses will check but think no deterioration on them
-Repair/replace other wiring as needed I’ll check
-Replace spark plugs and wires 10 of the 12 have been changed A1 is solid as is B5
-Check/replace vacuum advance capsule
-Repair centrifugal advance
-Adjust throttles and linkages, replace linkage bushings all look good
-Replace oil switches, if leaking no leaks
-Reseal cruise control bellows probably will remove them and the Ac pump
-Replace all fuel hoses-injectors, feeds, returns done already
-Probably other things I've forgotten
These repairs are MUCH easier with the intake manifolds removed and virtually every old Jag V12 needs most or all of them performed. It's a big job but perfectly DIY-able if you just work slowly and carefully. Very satisfying and, in the end, much easier than tackling these repairs on the alá carte approach.
Do it all, do it right, do it once.
Cheers
DD
I suggesting positioning your new loom alongside the fuel rail.....or anywhere except clamped to the floor of the "vee".
I'd also suggesting "doing the vee". This is a bit of jag V12 slang for tackling many issues at once.
-Remove intake manfolds to replace cam cover gaskets and half-moon seal no leaks so not going to touch anything
-Replace injector harness my next move
-Replace vacuum hoses will check but think no deterioration on them
-Repair/replace other wiring as needed I’ll check
-Replace spark plugs and wires 10 of the 12 have been changed A1 is solid as is B5
-Check/replace vacuum advance capsule
-Repair centrifugal advance
-Adjust throttles and linkages, replace linkage bushings all look good
-Replace oil switches, if leaking no leaks
-Reseal cruise control bellows probably will remove them and the Ac pump
-Replace all fuel hoses-injectors, feeds, returns done already
-Probably other things I've forgotten
These repairs are MUCH easier with the intake manifolds removed and virtually every old Jag V12 needs most or all of them performed. It's a big job but perfectly DIY-able if you just work slowly and carefully. Very satisfying and, in the end, much easier than tackling these repairs on the alá carte approach.
Do it all, do it right, do it once.
Cheers
DD
IF the loom doesn’t work think I’ll go and buy a XJR and stick the engine and box in this lol
#29
03-31-2019, 04:24 AM
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Grant Francis (03-31-2019)
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