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So couple months ago I took on a huge project by buying a jag v12; now I changed the plugs, wires, cap, and rotor but there are still a few problems that I can’t find the issue with; I bought a new battery for it and it’s been sitting for about a week and now it’s dead so I think I have a runaway ground or something, it will rarely start but once it starts it is perfect but when I turn it off it won’t start again. Now I know that more people have knowledge abt this and I(m18) am personally a Chevy guy have now bought another 89 xjs coupe which has an overheating issue, how do I replace the thermostats and what radiator/fan combo should I put in?
I note that the engine snap shows it is what is known as a Marelli car. 1989 was the change year, and based on Vin Number of course, BUT, somewhere around May 1989 BUILD DATE is the change over.
Model year etc means nothing.
Just remember that when looking for advice, and maybe even add "Marelli" to your Sig via the CP tab at the top left, saves a lot of frustration.
Your battery drain is most likely some aftermarket item, Imobiliser, Alarm, Stereo etc. I always return these beasts to STOCK STANDARD, then once sorted, refit the "stuff" is its really needed.
My sticky at the top might throw some light, albeit Lucas related, but the basics are the same.
Spending a day or 2 or 3 cleaning and cleaning EVERY connection in the engine bay is never wasted time with these.
Ignition switch electrical section is now becoming very common for "no start". I have a PDF to sort that if you want it, just ask.
Have fun.
Last edited by Grant Francis; Aug 26, 2023 at 03:31 AM.
Reason: Brain to fingers: WAKE UP.
I note that the engine cnap shows it is what is known as a Marelli car. 1989 was the change year, and based on Von Number of course, BUT, somewhere around May 1989 BUILD DATE is the change over.
Thanks for the advice; by the way the coupe is Lucas and the cabriolet is marrelli. The cabriolet(battery drain) seams to have an aftermarket alarm so I will definitely look into that.
FYI the factory alarm system in an '89 will drain the battery over time, but not in a week with new battery.
On the convertible, check the position of the lights behind the front seats, they rotate up and down to change settings -- ON/OFF/Door Switched -- it is very easy to have accidentally switched in on, and in the daylight not notice it. One of those lights will drain your battery in a few days.
Once you find and eliminate your parasitic draw, unless you drive the car regularly, it's good practice to have a battery tender hooked up.
Spark problem in my 89 xjs convertible
