I have three jobs I'd like to do on my 92 XJS V12 convertible and would appreciate advice from experienced XJS owner/mechanics as to just how difficult each job is for a reasonably competent but aging wrencher and how much time each one would likely take.

1) Replace all coolant hoses.

2) Replace plugs wires and Marelli distributor.

3) Replace fuel rail hoses and kit as in V12 Performance.

If you could use a 1 to 10 with 10 being an experienced Jaguar mechanic I'd really appreciate it.

Thanks in advance guys.

 

None of this stuff is very complicated

1. Pretty easy, there are a few fiddly ones but recall the old hoses are trash, so you can simply cut the old hoses with a razor blade and peel them right off.
(2/10): You are just removing hoses and replacing them, but some can be annoying to access

2. Wires are super easy to replace, don't know about the marelli in particular. Do you mean you are replacing the entire distributor or a service like cap and rotor?
(1/10): You are just unplugging wires and plugging new ones back in

3. The fuel rail hoses are a fairly easy job, the biggest pain in the butt is getting old, very hard hoses off the injectors and rail. The kit from V12 performance is kind of a dumb price. You can get the ferrules, seals, and even new pintle caps and filter baskets for less than that buying the supplies from injector-rehab and hose from your local autoparts store.
(3/10): You are just undoing the fuel rail and removing all the old hoses and putting new ones on. Probably the hardest part will be unplugging the electrical connectors on the fuel injectors

I take difficulty to mean "technical prowess" and not necessarily whether its tedious or a pain to do. Replacing all hoses is tedious, cutting off 12 FI hoses and replacing them can also be tedious but none of these things is beyond the average mechanic. People just like to psych themselves out about european cars.

 

You'll see your injector in the table towards the bottom of the page. Search the part number to nab all the things you want. Like I said, just buy FI hose at a local store and cut it up yourself.

Injector rehab Bosch Denso Pintle Cap

 

A 92 doesn’t use the 12 little hoses. There’s only two hoses tying the two rails together, and one long one in and one long one out. The injectors mount directly to the rail with o-rings.

 

Is refurbishing your own injectors a thing? Is that cap the thing that makes the spray pattern? I'm curious now as my MPGs are dropping like a rock yet my entire ignition system is 'new' end to end except the injectors themselves.

 

If your distributor is a genuine Marelli and in good condition I would not replace it, the new ones are no where near the quality of the original. I have one of each.

 

Good advice . Well put.

 

The jobs are all easy. Grant and Greg would both say, that it would make sense to lock yourself in thr garage with enough alcohol whennyou are doing the hoses... It isn't complicated, just frustratimg sometimes. Barely seeing where they go but also some hoses are just a tight fit.

The fuel hoses and HT leads are a piece of cake

 

Well, I dunno about 'refurbishing'....but there's lots of guys who DIY injector cleaning. Check on You Tube

If you want or need more than that, I suggest....

Jaguar Fuel Injector Service



I think the pattern is established by the tiny orifice/outlet/nozzle/whatever at the tip of the injector itself. I'm not entirely sure what function the pintle cap serves.

Cheers
DD

 

The cap protects the little needle.

 

As has been said 92 could have O ringed injector rail. IIRC the change was in the 92 model year.

- Replace injector O rings as they will most likely be hard.
- DIY clean injectors.
- I would measure the resistance of the ignition leads and replace if any were bad.
- Replace ALL plugs, make sure you gap them correctly.
- Inspect distributor cap and rotor- replace ONLY if needed, genuine Marelli items are far better quality than the aftermarket replacements.
- Replace coolant hoses including the hard to get at heater hose.
- Change all fluids, including trans and diff.

 

Thanks, I kind of thought this but couldn't actually recall every hearing about the later V12 injectors, so I second guessed it.


And to answer OP, the pintle doesn't really affect spray pattern, but they often break so they are good to replace and they sometimes are removed to give the end of the injector a good clean. Replacing the filter baskets can be worth doing though.

I'm sure you can locate the parts for your injector once you identify which it is. Either way, it means the $100 kit from V12 performance definitely wouldn't be worth your time!

 

Hi Vancouver XJ6

If your mpg is dropping it could be the Vacuum pipe on you FPR (Fuel Pressure Regulator)

As a loss of Vacuum could increase Fuel Pressure and make your Car run rich and give you less mpg

So Check you are getting Vacuum to the FPR and also check the pressure in the Fuel Rail as maybe it could be a faulty FPR

 

FPR = fuel pressre regulator

not that he goes looking for a fuel pump regulator...

 

Hi Daim

My bad, I meant Fuel Pressure Regulator and so I have done a quick edit

 

Change or clean the air filter. Don't ask!!!


Carl

 

Hi NC Jagman

There are some who say that changing the Spark Plugs on an XJS is a 'right of passage' for any aspiring owner

Where having done this job myself I would have to agree, although for someone like myself with almost no mechanical experience

It could be compared to 'Building a Ship in a Bottle' where everything seems to be in the way of what you're doing

And above all this is not the kind of job you want to rush, as one mistake like a Cross threaded plug, could completely ruin your engine

Easy to do and just one of the reasons that I'll never take my Car to a 'Shop' to be fixed

Where for just Changing the Spark Plugs it could Cost $500

As while changing the Spark Plugs on most normal Cars could be done in well under Two hours

Changing the Plugs on an XJS could well be measured in days

Where since this was the first time that I'd ever done this job, changing the Spark Plugs took me nearly Three days!

One of the worst parts of doing this job getting to the Spark Plugs underneath the Air Con Motor,

Which was a real 'Bar Steward' to lift out and an even bigger 'Bar Steward' to put back because its such tight precision fit

And when I finally got to them, they were in so tight. that they were a 'Nightmare' to get out

So it would be a good idea to spray them all with Penetrating Oil, just like I did

Which kind of had me wondering if those two plugs had ever been changed during the life of the Car

But when you put the New Spark Plugs back, they only need to be finger tight, plus about 5 degrees

As you need to be Careful, that you don't strip the Threads by over tightening

If you are taking the Fuel Rail off, then this will make the job a whole lot easier but take Photographs of everything you do

And also label every lead or wire that you take off, as its so easy to get lost when they have to go back

Based on the Fact it took Three days for me to do this job, in terms of difficulty I would have to rate it as 7/10

Though if I have to do this again on one of my other XJS's then I would think I could do the job in just a couple of days

For as I may have said before, this is not the kind of job that you want to rush

The best results can be achieved if you take your time

You can see how I did mine on Page: 8 of my 'Cherry Blossom' Restoration Thread

And here is the Link straight to it: https://www.jaguarforums.com/forum/x...-122634/page8/

 

I hate to piggyback on OP's thread but maybe its all relevant anyhow - does the size of new Vac lines actually matter in these cars or can you just order 10ft of [standard size silicone hose] so long as the thing fits over the nipple(s) I'd imagine on any 'new to me' car it would be nice to delete the vac line maze and just have the minimum necessary ones in new hoses.

Edit: My car would seem to have different sizes connected to other size hoses like evidence of some shoddy DIY work with several plastic smaller to bigger connection pieces here and there

 

It does not matter. Standard 4mm silicone vac tube is a great idea. Also worth replacing that to the gearbox modulator, and the rubber elbow on the modulator spigot. When I did mine (the old one was not porous) the responsiveness of the gearbox was transformed.

 

Very interesting, it's been lazy going from D to 2 where as last summer the shift was so hard (proper imo) I was afraid of gearing down manually.

Is the gearbox one easy to find or is this one of those things where we have to zoom in on 1980s diagrams to find the line?