Hello! I have an '87 XJSC that needed a new battery after 6 years but just installed it and still just cranks well but loses juice after couple start tries, alternator light (lightning bolt) now on but also did the full throttle TPS test (Thank you Australia!) with no clicking so figure that is the first issue. Im in love with this car as it was my Mom's and still has 43k miles and only issue in 6 years but now live out in countryside so Im learning how to be my own mechanic. Thanks for any advice/input but my sense is new TPS first..?

 

Before attempting further diagnosis, charge the battery for 6 hours at 2 to 5 amps. Once charged, the battery should have a minimum of 12.6 volts across the terminals when checked with a voltmeter.

 

Will do! Just purchased DVM since I figure time to start with the basics. Thank You!

 

Charged battery and tested above 12.6 w/DVM as well as same at connection. Turn ignition to on and open throttle but no obvious clicking humming sound other than fuel pump. Where the throttle manually stops is against an odd wiring with metal tip that fits between a metal clip. Seems flimsy as it hits it. I'll send pics when Internet isn't overwhelmed in California.
Thanks again.

 

#1 rule of a V12, DO NOT THROW MONEY OR PARTS AT IT, that will rarely fix it.

Then comes:

They are SIMPLE beasts.

AGE is causing issues also.

NO Injector pulse is a good place to start, SYSTEMATICALLY.

Also, after the "humming" stops, CAREFULLY crack a fuel line and observe if you have fuel AT the rail. The pumps can, and do, run, but sometimes they simply do not pump fuel.
PLEASE be careful here, as fuel spillage will take place..

The TPS can fail, for sure, so test it carefully before replacing it. At that mileage, I would be surprised it its faulty, but things do go bang in the night.

That metal thing you mention, MAY be the arm of the throttle fuel switch. It is a flimsy thing at best, BUT, it will NOT stop the engine running.

The CTS (Coolant Temp Sensor), is the root cause of starting issues. Unplug it, bridge the terminals IN the plug, and try the start again.

 

I really appreciate your help getting me started with this beauty. I have just received the XJS ROMw/supps HE 5.3 to '88 so I am sure I will have more questions as I progess. Thanks Again, Dave Tyler

 

More questions...HA. You'll be here for life...and you'll love every minute of it.

 

Apologies Grant my autocorrect called you Greg! Thanks again I'll be reading up on the CTS now as well.

 

DT T,

If you haven't seen it, at the top of the forum are some 'sticky' links to important info. One of those is to this:

https://www.jaguarforums.com/forum/x...he-v12-178286/

Grant has brilliantly and graciously put in one place everything you need to know about dealing with a No Start condition. Download the .pdf and enjoy.

Cheers

 

Thanks! Definitely appreciate Grant taking the time to demystify these gorgeous engines! I am so thankful for this forum as I am very green beyond oil, AC recharges and minor routine maintenance but live in the country now so learning!

 

FORGOT.

It happens.

I will add this to the PDF at some stage and get Graham to update it.

If the car has an Imobiliser/alarm.etc of AFTERMARKET type, REMOVE it from the car BEFORE you begin diagnosis.

These things are not popular down here, hence the "forget". However the USA market seems to be flooded with them, and they do reek havoc. Mainly from lousy installation.

Repair the wiring as best as possible after the removal

Now start the process of WHY.

It may simply start and run as designed, mine did.

 

Thankfully I am leary of add ons but when I recover completely from hernia surgery and get my baby back on the road, I might want to add a K&N air filter to let it breath. But of course I would appreciate your thoughts if it's even necessary..Thanks again. Dave

 

Take your time, the Jag is one PATIENT car.

K & N to me is wasted beer money, but then I am down here, and do have my opinions, and DUST is our friend 6 months of the year.

The OE spec paper filters, changed regularly, are as good as you can want.

Waking up a V12 is simple, and cheap, BUT, is reliant on Statutory needs, we got zero.

I have MANY write ups on getting to this, Aussie style. Some are too big to attach, so if you wish to PM your email address, I can send what I have to you.

MY ONLY RULE, is the Forums MUST be kept up to date with what is being done, that way the archives are there for when we are not, fair trade in my opinion. No one has bent my rules to date, makes me happy.

 

Hello, after checking new battery charging fine but still just cranks well. Moving on to TPS testing and could not get a click when turning throttle open (not slowly this time Thanks Grant!) so testing TPS, cleaning ECU (per Grant's instructions) next step. Here's pics of my throttle and odd metal clip it hits fully open. Can lift vertical clip out and just slides back in place but certainly bends oddly with full contact. Won't obsess on it now as it has always been that way. 43k original miles and no modifications. Thanks again to everyone!

 

Purchased XJS ROM but no mention of TPS until HE supp had how to replace throttle potentiometer and location. Found plug, disconnected and looked good then reconnect and it tested 5+ on dvm so on to ECU. I will soon brave the CA stores and buy a lot of lemons to clean it lol. Grant told me to look for the box on rt. front side and I see a silver box that I will upload when can. Any further tips to remove it carefully and what not to do would be invaluable.

Found TPS and plug!
Thanks again!

 

here is a guide I wrote about this item (power resistor). Also a photo of it.

 

Thank you for the information and picture of power resistor. I'll be reading up before I dive in, so Im certain I'll have more questions lol.

 

I removed ECU (already very clean) and cleaned face and plug but no change. I am enjoying getting familiar with this engine. Guess it's check spark time but would appreciate any further how to steps for preceding carefully again. Thanks especially to Grant and Greg!

 

FYI I'll be starting with checking the CTS first before pulling a spark plug to see if it's wet.

 

Hello, I located the CTS and it came out easily and looks good (2 small little prongs) and will find a tiny wire to bridge those two and replug. I'll send pics when I can and see if that gets it started again. Loom also looked fairly clean so don't think that's an issue. I have been reading the Kirby Palm manual and ROM and see I'm probably due for new dist. Cap and plugs, but realize I need to get the injectors to click first. (On an aside it is definitely my throttle microswitch that appears to have a loose wire but will ask more about that later)