XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

MAP sensor testing(internal ECU). Inconsistent running/starting

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Old Nov 17, 2025 | 07:40 AM
  #21  
Greg in France's Avatar
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Originally Posted by Ffirebug
That looks exactly like the leak, Greg. Kinda like the idea of smearing the sealant instead of tearing the timing apart to change a gasket. I really don’t want to get into that now, but it doesn’t look too bad. How long you think it’d take a first timer to pull the manifolds and do both sides?
  • unclip the air temp sensor connector on the B bank trumpet
  • unclip and remove the airbox outers and air filters
  • undo the manifold to head 7/16ths (I think) nuts 2 per runner = 24.
  • undo the fuel feed and returns
  • lift off manifolds (two people, one per side).
Half to 3/4 of an hour max. Have a telescopic magnet on a stick thingy handy so you can pull out any dropped nuts and get the washers off the studs easily. BUNG UP INTAKE HOLES IMMEDIATELY THE MANIFOLDS ARE OFF.

Cleaning the V with carby cleaner and small brushes, quite a time depending how bad; maybe a day. You do need compressed air to do it properly, the V will have loads of grit on it.
Then clean round the tappet block to head seam and rough up the ally with sandpaper or steel wool, so the gunk can key to it, one hour. Use high temp silicone gunk.

The camcover gaskets MUST be done at the same time. They leak. It only takes an hour to remove the bolts and lift the covers off. Then clean the surfaces, new modern gortex/metal sandwich gaskets, lightly dressed on each surface metal and gasket, with Gascacinch or Permatex aviation No. 3, and replace. BUT the Great Palm recommends obtaining slightly longer fixing bolts with Allen Key heads, and using bellville-type domed spring washers under them. Very good plan, see my photo above.

I also strongly recommend using these ally half mood seals, supplied by this guy:
https://www.ebay.co.uk/itm/324493972...Bk9SR8CSs6DSZg

although Grant reckons the rubber ones plus sealer will be fine, and he is probably right; but I like belt and braces, and I am not as skilled as Grant!
All in, once you have accumulated the parts and can start in, a Saturday and Sunday, working all day should do it.
Good luck.
 

Last edited by Greg in France; Nov 17, 2025 at 07:44 AM.
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Old Nov 17, 2025 | 08:38 AM
  #22  
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I’ll start getting her tore down tonight. Not sure about the beveled spring washer but I’ll see if I can take an original and try and match something up.
 
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Old Nov 17, 2025 | 12:09 PM
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Old Nov 18, 2025 | 03:01 AM
  #24  
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I forgot to mention: also unplug the injector loom from the car loom (RHS inner wing towards the front) before lifting off the induction!
And a few other loom connectors such as amp to coil leads, full throttle vac switchh, etc etc round that area.
 

Last edited by Greg in France; Nov 18, 2025 at 09:39 AM.
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Old Nov 18, 2025 | 03:25 AM
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AND

Label everything, your memory is not as good as you think.
 
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Old Nov 26, 2025 | 04:28 PM
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No major updates just buttoning up this before a test drive. I’m trying to put everything together in the boot. Does anyone have some pictures of the spare tire mounting, all the shields around the battery and the fuel pump and hose routing? Someone else took this apart and I’m not sure if I have all the parts. Plus the fuel pump hose looks wrong, like it may need a 90 degree fitting or something. There’s an old pump in a box in the trunk so they messed with that too.
 
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Old Nov 27, 2025 | 03:06 AM
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In this diagram, which is pretty clear:

https://parts.jaguarlandroverclassic.../brand/jaguar/

14 = feed from main tank
13 = breather from sump tank back to main tank (ignore the extra 14 mistakenly also on it!)
20 = feed to pump

From the pump a flexible goes to the filter which is mounted behind the spare wheel.
https://parts.jaguarlandroverclassic.../brand/jaguar/
From the pump the high pressure flexible goes to the RH front bottom corner where it attached to a 90° compression fitting.

 
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