XJ6 & XJ12 Series I, II & III 1968-1992

XJ12 Non starter

 
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Old 02-19-2019, 02:46 PM
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Default XJ12 Non starter

Iím a newbie here but own a few classics but canít get my head round this issue

1984 XJ12 S3

Car has been sitting as injectors had issues with bad fuel a few years ago, injectors and fuel tanks cleaned now

Plugs have been changed and it will now run with stuff spayed into the inlets so spark good etc

when ign turned on i donít have the initial prime of the injectors, if I power the injectors up I get spray from them so I know fuel pressure is there but have nothing on cranking

fuel pump runs constant so guessing a relay issue on slam panel?

Ive done a search on here but canít find much, I need to check full throttle switch tomorrow

i look forward to your replies 👍
 
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Old 02-19-2019, 09:24 PM
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Before too much gets too confusing, slip down ONE section to the XJS Section.

I have a "sticky" at the top about what you are seeing, and maybe it will assist.
 
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Old 02-20-2019, 12:59 PM
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Yes I have had a read

I’m know getting prime on the injectors but not every time

no injector click with full throttle applied

plus I set light to it this morning accidentally and had to put the fire out so pretty much left it for today
 
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Old 02-20-2019, 08:50 PM
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Bugga.

1st coffee still brewing, so I will think some more and reply later tonight, our time.

Fire is from what, if you know, as that could be the key to NO start.

This list could be LONG.
 
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Old 02-21-2019, 02:44 AM
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Fire was from a leak on fuel line near chassis rail must be the return line as still have pressure at rail
 
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Old 02-21-2019, 03:02 AM
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If the pump is running whenever the Ign is ON, that is possibly a simple bridge in the relay socket, and rather common when diagnosing fuel pump issues. The ORANGE wire of that same socket is the EARTH for that relay, and controlled by the ECU. Without that circuit, the timer for the 2-3 seconds of pump run at each Ign ON is inop.

NO Injector "click" as TPS is moved from Idle to WOT with Ign ON is NOT a good sign.

The CTS (Coolant TempSensor) may NOT be supplying a feed back, and it will NEVER start with that fault, soooooo, unplug the CTS, use a paper clip to bridge the terminals IN the socket, as this will fool the ECU to think a HOT engine, and it should start.

The TPS is dead, COMMON.

The shielded wire (Coax for some) from the Ign AMP, to Pin #18 of the ECU is broken, COMMON, especially when fiddling has taken place.

EFI loom, in the bottom of the "V" is shorting internally, COMMON.

The EFI resistor pack, not sure where it is on a S3, has very dirty contacts on its multi pin plug. MANY threads on this in teh XJS section, mainly by Greg in France and Orangeblossom.

Thats enough for now, as its beer o;clock here.
 

Last edited by Grant Francis; 02-21-2019 at 03:03 AM. Reason: spelling still sucks
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Old 02-23-2019, 10:39 AM
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Def don’t have injector click with wide open throttle where now guys
 
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Old 02-23-2019, 11:17 AM
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Originally Posted by notenoughtime View Post
Def donít have injector click with wide open throttle where now guys
As Grant said, and as his examples indicate, the 'could be' list is long. You just gotta pick a jumping-off point and dig in.

I'd go with jumping the CTS terminals. That's a really easy place to begin.

After that, check the shielded wire. Lots of info in the archives.

Cheers
DD
 
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Old 02-23-2019, 11:19 AM
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Originally Posted by Grant Francis View Post
The EFI resistor pack, not sure where it is on a S3, has very dirty contacts on its multi pin plug. MANY threads on this in teh XJS section, mainly by Greg in France and Orangeblossom.

Thats enough for now, as its beer o;clock here.

Same as on the XJS: RH side of the engine bay, way forward, down low and out of sight

Cheers
DD
 
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Old 02-23-2019, 11:21 AM
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And check for 'key on' supply voltage to the injectors. Pink/black wires.

Cheers
DD
 
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Old 02-23-2019, 12:05 PM
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Originally Posted by Doug View Post
And check for 'key on' supply voltage to the injectors. Pink/black wires.

Cheers
DD
i have voltage at injectors both wires though
 
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Old 02-23-2019, 12:06 PM
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Originally Posted by Doug View Post
Same as on the XJS: RH side of the engine bay, way forward, down low and out of sight

Cheers
DD
cleaned said plugs and pack plug 👍
 
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Old 02-23-2019, 12:08 PM
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Originally Posted by Doug View Post
As Grant said, and as his examples indicate, the 'could be' list is long. You just gotta pick a jumping-off point and dig in.

I'd go with jumping the CTS terminals. That's a really easy place to begin.

After that, check the shielded wire. Lots of info in the archives.

Cheers
DD
need to check shielded wire to pin 18, and I did try jumping cts which clicked the relay but that was before I cleaned the resistor pack plugs
 
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Old 02-23-2019, 12:10 PM
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Originally Posted by notenoughtime View Post


i have voltage at injectors both wires though

Ok, good. That's something. Check this item off the list and keep going.

You'll have "+" voltage on both wires until the ECU grounds one of them

Now jump the terminals on the CTS connector.

Then clean the connection at the resistor box.

Then check the shielded wire.

You're finding out what isn't the problem. That's how it goes with these cars.

Cheers
DD
 
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Old 02-23-2019, 12:11 PM
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Ok, you're ahead of me on posting !

Just keep going

Cheers
DD
 
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Old 02-23-2019, 12:14 PM
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I have voltage at resistor pack also
 
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Old 02-23-2019, 07:18 PM
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I think there be an EFI loom issue.

Even with the Shielded wire AWOL, the Injector click when the TPS is rotated from Idle to WOT quickly, should still be present. BUT, if there is a loom issue, NO.

I would also bridge the ATS (Air Temp Sensor) socket. MAYBE, and yes, MAYBE the ATS and CTS are wrongly plugged, been there, took days to find that, and that was before Forums and computers, whoopee.

Attached is a Pin out for my 1985 XJS, basically the same as your beast.
Also an EFI schematics that has got me out of troble many times.

You say it runs with stuff sprayed up its snouts, so simple, the fuel aint getting through the Injectors.


 
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XJ-S ECU Pinout table.doc (25.5 KB, 6 views)
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Old 02-24-2019, 03:08 AM
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Originally Posted by Grant Francis View Post
I think there be an EFI loom issue.

Even with the Shielded wire AWOL, the Injector click when the TPS is rotated from Idle to WOT quickly, should still be present. BUT, if there is a loom issue, NO.

I would also bridge the ATS (Air Temp Sensor) socket. MAYBE, and yes, MAYBE the ATS and CTS are wrongly plugged, been there, took days to find that, and that was before Forums and computers, whoopee.

Attached is a Pin out for my 1985 XJS, basically the same as your beast.
Also an EFI schematics that has got me out of troble many times.

You say it runs with stuff sprayed up its snouts, so simple, the fuel aint getting through the Injectors.
ATS and CTS plugs are different arenít they? Is CTS mounted front of engine left bank with spade connectors and ATS left air filter snout with mini timer plug

ive pulled no 1 left bank injector out but donít get spaying of fuel every time ign is turned on now
 
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Old 02-24-2019, 04:01 AM
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Ign ON< the Injectors SHOULD NOT spray, Repeat, SHOULD NOT spray. If they do, or did, then the EFI loom is #1 on my list, followed closely by a TPS out of range.

Injectors DO NOT spray every time the key is turned on, God forbid, the thing would fill with fuel in a heartbeat.

The CTS and the ATS SHOULD both have the same 2 pin Injector style plug. Thats why they can be mis-plugged sometimes. If the CTS has 2 seperate spade terminals, without that Injector style plug, then someone has fiddled, and maybe that loom, which travels aft, via the ATS has also been messed up. That pin out will clear that up in a few minutes.

Forgot, its been 41c all day and now at 9PM still 38c, so declared Beer O'clock at 9AM.

This attachment for checking and adjusting the TPS may well be worth ticking off the to do list, as it may be PART of the cause of the NO running.
 
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Adjusting the HE TPS.doc (27.5 KB, 4 views)

Last edited by Grant Francis; 02-24-2019 at 04:28 AM.
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Old 02-24-2019, 10:24 AM
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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.
 

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