Today my adult son wanted to drive the Jag since it he hasn’t driven it since I first acquired and before I did any of the refurbishment of it over the past year. Initially, I underestimated how warm the engine was after a short drive down the street and when showing him how to feather the choke off, it went to a very low idle (under 600 rpm) and stalled. I had him put 1/2 choke on an it started right back up and we had an enjoyable drive together and as we drove we were able to close the choke completely.
When the car was in the driveway, I asked him to assist me in checking that all the lights worked since it is dues for its state inspection. Everything except the headlights worked great. Is suspect a loose wire and/or blown fuse and that will take further investigation tomorrow. I had him leave the car in the driveway, since I didn’t trust him to pull the car into the garage next to my wife’s car.
About a half hour later I went out to start it and pull it into the garage. When I turned the key, without using the choke or touching the accelerator, the engine fired right up but went up to 3000 rpm’s in a second. I immediately reached down to grab the accelerator thinking it might be caught on the carpet, but it wasn’t. I then turned the key off and the engine stopped.
I then popped open the bonnet thinking that the accelerator linkage might be snagged or needed lubricated, but it too was not bound up nor pulling on the carb linkage. I then went over to the carbs thinking that the pistons or butterfly valves might be stuck. After removing the plenum, I could see that the pistons were shut and by playing with the linkage, I could see that the butterfly valves were closed and not stuck in any fashion.
By way of background, on Friday I took the car out for a long test drive, warm enough to turn the choke off, but when I would come to a stop sign or traffic light, it would drop to 500 rpm and then stall. When I got home, I adjusted the carb mixture screw open another 1/2 turn, bring it to a total of three full turns from closed. After the incident today, I closed the mixture screw back the 1/2 turn I had adjusted and this time when I started the car it immediately jumped to 1500 rpm with no accelerator or choke usage.
Rather than play with the car in the sun outside, I was able to get it back into the garage without touching the accelerator, because when I did, it seem to rev very quickly and very high. About two months ago, I reinserted the spring in the pedal housing because I didn’t think the accelerator was rebounding fast enough when I let off the pedal. But this issue has me totally confused. Thoughts?