I just purchased a 1995 Jaguar XJS, the previous owner let it sit a number of years, not quite sure how many. The fuel tank had rusted out. They had the fuel tank along with the pumps replaced. The car started right up but with a few misfires, which is then when i purchased it. I started by cleaning out the fuel rails as there was still a little rust debris in them, and the car ran better but with the same misfires. I then replaced the spark plugs and eliminated 1 misfire but still had 3 misfires, i pulled the injectors and sure enough 2 were clogged one was stuck. I was then able to get 2 working properly having to replace 1. After putting it together now i have multiple completely random misfires appears to be about 6-8, some being hard to tell, i have done a compression test, everything checked out good, everything is getting spark. Im at a loss on whats happening, was running good besides the 3 misfires, and all of a sudden running horribly. I used a noid light to check injector pulse and every thing is getting pulse. Any ideas on what could be going on? I have worked on many vehicles being successful finding issues. I am also fairly competent in when it comes to these things, any advice would be helpful.

 

Sorry a 1995 xj12 not xjs.

 

Hello AskJeff123,

Good job taking on this car, and hopefully, saving it. It will be worth the effort. A couple of ideas for now:

You didn't mention if the car is throwing any OBD2 codes (it is compliant even though it is a MY1995).

I sure hope the fuel filter was replaced when the tank and pumps were done. If the car was sitting and rusting, the fuel filter would probably be shot. If you don't know, then replace it. It is above the left rear wheel. It is not easy to measure the fuel pressure directly, but you can put the fuel line into a bucket above the engine and key on (without cranking). There should be a good healthy flow for 2-3 seconds during the key-on fuel pressure prime.

Also make sure your gasoline is fresh, premium, and from a trustworthy name-brand station (water contamination seems to be more likely at generic stations).