Hi all, I am a newly registered forum user, but I’ve spent some time researching prior forum topics in search of answers on the issues plaguing my recently acquired 1986 XJ6. Any insight would be appreciated, or even direction to other forum topics that would address these problems. I’ll start with where I am with the car now, and the backtrack to how I got here.
Cold start takes about 3-4 attempts. It will start but immediately die the first few times. Once it gets to the point at which it stays running, it runs smoothly, but idle is high - hovering around 1500-1600 rpm. Giving it the slightest bit of gas kills it. Putting it in gear, whether drive or reverse, kills the engine immediately.
I bought it about 2 months ago, and it was running at the time, but with a known misfire at cylinder 6. The car had sat unused for a number of years until the PO bought it in non-running condition. He had the left fuel tank drained, replaced the starter relay and fuel pump, and refilled the left tank. It then ran, but with a misfire at cylinder 6 (per the Jag/Bentley/Aston mechanic who did the work) and the fuel gauge would not work. The shop recommended running injector cleaner through it because they suspected a gummed-up injector. PO would start it every week but drove it less than 15 miles in his year-and-a-half of owning it.
When it arrived at my house, I noticed that idle was high, at about 1100 rpm in park. It ran very rough, presumably from the misfire, but it started, drove, and stopped fine otherwise. In an attempt to get it running better, I ran a can of seafoam through it at the throttle body. Things did not go well thereafter. I tried to drive it around the block, but idle was then stuck at 1500-1600 rpm. As I would give it some gas, it would stall and die out as soon as it hit 2000 rpm. I made it home after it died four times. Sitting in the driveway in park, idle stayed at 1500-1600 rpm, and it would stall if revved past 2000 rpm. It would not stop, however - the tach would drop, and it would climb back to high idle. A local mechanic with prior Jaguar experience agreed to look at it.
When I started it to bring it to the mechanic, the misfire seemed to have been cured: the engine ran amazingly smooth. Idle still hovered at 1600 rpm, but now it would smoothly rev (in park) over 2000 rpm without a problem. The drive to the local mechanic was problematic though: in gear, it would stall and die with the slightest touch of the throttle. Further, the previously well-functioning brakes did little to stop the car despite depressing the brake pedal to the floor. The mechanic’s shop was accessible via a little-used side road, so I essentially coasted, foot off the accelerator, the entire drive. Apparently the engine got enough fuel via the high idle to continuously run at about 5 mph. I think I recall a noticeably louder-than-normal whine from the fuel pump, but I was distracted by the worry of ineffective brakes (not that I really needed brakes, because all I had to do to stop the car was to press the accelerator and it would die).
The local mechanic believed the AFM to be the culprit. Fortunately, the PO included a bin of spare parts with the car, and I had a new-in-box AFM. We installed it, but it still dies with the slightest bit of throttle. He believes that bad fuel is the problem, and he thinks the tank needs to be dropped and cleaned, but he no longer wants to work on it. It’s back at my house now, leaving its signature puddles on the concrete (three different leaks, which I’ll address once it’s running).
I don’t think that bad fuel is the issue, but I could easily be wrong. My first thought is that I somehow affected the throttle when I did the seafoam treatment: I did not have someone to hold the throttle open via the accelerator, so I manipulated the throttle lever manually while spraying the seafoam. Perhaps this affected some component of the throttle assembly? It looks fine upon visual inspection, but I admit that I’m not sure what to look for at this point. And it may be that the brakes are an entirely separate issue, but I can’t tell until it runs long enough to try to use them.
Any help would be appreciated. Thanks.