Good morning,
My 1987 XJ6 has developed an odd problem. She runs great when cold, then after she warms up (about fifteen minutes) I get a slight misfire and five seconds later she stalls suddenly and won't restart until she's cool again.

I've been through the entire fuel injection system thinking it was vapor lock - and replaced the fuel temperature sensor that was bad. I tested all the other sensors, and replaced all the fuel hoses while I was in there just for good measure.

Now I'm thinking that the new coil may be bad, I've got a broken wire somewhere, or the oxygen sensor has gone south. It's not very warm in Seattle this week, so ambient temperature doesn't seem to be an issue.

Any and all opinions as to where to look next will be greatly appreciated.

Thank you!
Eric

 

Ignition coil and ignition module are both likely culprits here. Both are notorious for giving trouble after absorbing engine heat and then working normally after cool down.

Next time it conks out check for weak spark or no spark.

Cheers
DD

 

Thanks, Doug, I appreciate the advice. I replaced the factory ignition module with Pertronix system, so when I get home tonight I'll start looking at the coil. This wouldn't be the first time I bought a new coil that was bad off the shelf.

 

Thanks again, Doug, it was the coil. On the way to the office this morning, I think I figured out why it faulted in the first place. I happened to glance down at the ammeter just as it pegged 18V and then went back to 11, or so. I'll be replacing the alternator this week; I'm not looking forward to that job.

Eric