I have an 1989 XJS, made in July of 1989. It has the Marelli iginition system in it. I have not driven the car in 7 years. It has been in a heated garage the entire time. I pumped all the fuel out of the gas tank and put new fuel in and tried to start the car. It did eventually start after several cranks and it ran very rough, for 2 or 3 min. I shut the car off and tried again, and it started again and ran rough. I thought it might be the plugs causing it to run rough. I changed all 12, what fun, it took me 2 days. When I tried to start it I got nothing. I changed both crank sensors, still no spark. I get fuel up to the fuel rails, but no spark. I checked to see if I got a spark out of the coil, but there is none. What can I check or change to get a spark? I greatly appreciate any ideas.

 

Did you check both coils?

 

Thank you. No I have not. Is there a way to check them before replacing them?

 

Do you have a multi-meter?

I haven't been able to (easily) find the specs for a Marelli coil. I think the primary resistance should be about .7 ohm and the secondary resistance about 5k ohm. DOn't take those numbers to the bank.

Alsocheck for 12v with key "on" at the "+" post of each coil (plain white wires) and at each of the control modules (also white wires)

Cheers
DD

 

It is highly unlikely you have lost both coils or ignites (although it is a possibility)

With the Marelli system there is a sensor on the flywheel for engine speed, ignition timing is not switched to the run mode until the engine is spinning at 350rpm. below 350rpm timing is engine speed dependent based on the input from this sensor.

I would be looking at what you touched when changing the plugs I would bet there is something in there that you have disturbed.

Check all of the wiring the white wires on the 2 coils are the primary these get hard and brittle I know mine are and the insulation is cracked check these are not broken.

Then go over everything you touched.

cheers W

 

Thank you Doug and warrjon! Great advice. I will let you know how I make out.