XJS v12 motor won't turn over
 

Hey everyone....need some direction on troubleshooting this issue. My XJS V12 recently had a full tune up done about just over 5 weeks ago. Ran like a stallion, super smooth, etc. It then sat in my garage for a month without driving. Now the car won't start!

Radio turns on and the door locks work so I'm not 100% convinced its the battery. When I had the tune up done, I had the mechanics check the alternator and they said it was perfectly fine. All the spark plugs were changed, etc.

Only the gas gauge seems to move when i try to turn the key over. I also hear a mechanical clicking noise when i turn the key. I've tried pumping the gas pedal in hopes that the fuel pump will lend a helping hand. I've also sanded down the contacts on the battery to make sure the battery cables were making good contact.

Any ideas/suggestions???

thanks!

Perhaps the clicking of a starter solenoid? Suspect the battery.

Graham

Just to make absolutely sure we're on the same page, by "won't start" you mean the starter doesn't operate, correct?

I'll assume that's the case.





Even a weak-ish battery will operate those things. Operating the starter takes real oomph! :-). I agree taht the battery should be a prime suspect. Charge it for a few hours and see if anything changes



That won't do anything to help the starter operate :-)




Good, because often loose/dirty cables are the problem



Yeah, make *sure* the battery isn't the culprit before looking at more complex fixes

Cheers
DD

wont turn over: the engine literally wont turn at all. 0 movement of the engine in a clockwise fashion viewed from the front of the car.

diagnosis: starter or battery

wont start: the engine will turn in a clockwise direction viewed from the front of the car, cranking over and over with no ignition.

diagnosis: multiple things could be at fault but the starter and battery are good.


ive had batterys that were in good condition and perfectly capable of starting any one or probably even several of my supercharged V6's at the same time, but wouldnt crank over the 11:1 compression 12 cylinder if i was pointing a gun at it. lol

lots of rotating mass + 12(lots of compression) = difficult.

"Won't turn over" has confused everyone for years. Most use it to describe a starter motor that isn't turning the engine. However, enough people use it to describe any "no start" condition that clarification is often required.

My Dad was one of those who would say "the engine won't turn over" even though the starter was spinning the engine like crazy....but the engine wouldn't start.

In the repair business these two terms were used almost universally to eliminate the confusion:

"Cranks, won't start"
(Starter operates; engine won't start)

and

"No crank, no start"
(Starter does not operate; engine won't start)

Cheers
DD

ive got a starter and alternator for sale.

Um....er....sorry to have to say this but this bit where you jump into every thread with your "I have a xxxx for sale" is getting pretty old.

We all know you're parting out an XJS. We seriously don't need multiple daily sales pitches :-)

Cheers
DD

Quick update everyone....I should also add that this had happened before once. The car randomly wouldn't start....we jumped it with cables and it ran fine for two months. The car then got serviced and sat for 4 weeks.

Don't know if this changes anyone's opinion or not....

Battery

One thing you ought to check is the starter cables...are they all tight and earthing properly........this is not a job i am volunteering to do you understand LOL. are you sure its the correct battery? its a hell of a lump to spin over.
Good luck

im seriously not posting them for you. the OP probably doesnt know about it.

and since i cant post a thread in the XJS section, and the parting out thread is banished to the basement of the classifieds, im going to keep posting the parts that are relative to the thread and the OP's issues.

Start by checking the battery. Put a voltmeter across the leads and read the voltage when you try to crank the engine.If it is below 10 volt you need a battery to begin with. You said it sat for a month or so which leads me to believe you just need a battery or at least a charge.


M90 now is the time to offer your battery for sale.

lol. its a walmart cheapo thanks to the PO. it wouldnt hold a charge long enough to make it to the buyers house.

Give it a full charge with a charger that has a de-sulfatation run before the charge proper. I have brough t back quite a few "dead" battaries that way lately.

Problem fixed. Turns out the battery wouldn't hold a charge because it was leaking. Popped in a new battery and we're good as new again.

@Jagvilly

Glad you are up and running again. If your XJS is not your daily driver and it is left for long periods, you may want to consider getting one of these....
This keeps the battery topped up even over long periods of time. There is a nifty connector included that you permanently connect to the battery, then all you need to do is connect the quick connect to the device, ie you don't have to disconnect the battery

Great tip, Sarc...thanks! I probably drive the XJS about 15-20 miles a month, if that. Right now it is running smoother than butter and as cool as a cucumber. My biggest issues are still figuring out why my right/front turn signal blinks like its on speed and taking my doors apart so i can see why my windows stop a half inch from completely closing.

I assume it is only the fron blinking furiously. As all the RH ones are wired to the same output presumably one or two of the other RH ones are dead. Replace the bulbs in the others and it will return to normal.

All the RH bulbs actually work well. The rear RH bulbs blink at the normal rate. my blinkers on my dash also don't light up, but i can hear them. Left side works well front/rear.