Just noticed that one of the 2 choke(?) pistons isn't moving. I can lift the piston on the good carb and it will drop freely. On the problem carb, I can't lift the piston at all (through the air intake) However, as soon as I loosen the 3 screws that attach the suction chamber to the carburetor, the piston moves freely again. If I remove the 3 screws, and take off the piston and chamber, the piston moves freely inside the chamber. The piston also moves freely inside the carburetor. It's only when I make the final tightening of the 3 screws does the assembly jam up. All have been properly cleaned. Thoughts or suggestions? I understand the importance of centering the needle, but it doesn't seem like something that would cause this problem. Hope my description is clear enough.

Your patience with my previous dumb questions has been greatly appreciated :-)

Submitted by NE48-48878 on Wed, 10/28/2015 - 19:36

Well, after long delays, including struggling with some fuel delivery issues, the car now starts, but won't stay running, even with the gas pedal to the floor. Worse still, there's a periodic spray of fuel from the starting carburetor at regular intervals. Short video can be found here: https://youtu.be/mYtchGc0mu8. A knowledgeable Mk 2 owner noticed I have some minor fuel leaks that I need to take care of, and also thought the engine was running lean. I was wondering, though, if the video might spark other specific suggestions from someone out there.

Submitted by NE48-48878 on Thu, 10/24/2013 - 12:14

Could someone please confirm that the Jag's firing order is 1-5-3-6-2-4? I don't see this information anywhere in the manuals or books I have for the car. Thanks.

Submitted by NE48-48878 on Wed, 10/16/2013 - 22:45

Still plodding along with this. Another quick question: How hard should it be to lift the carb piston with one's fingers? In other words, is it possible to put too much damper fluid? Right now, there's a fair bit of initial resistance, but then it lifts easily enough. Thanks again.

Submitted by NE48-48878 on Sat, 09/28/2013 - 17:35

Good to know :-) Had also come to the same conclusion, based on information at the website of scpart.co.uk.

By the way, is it only my replies that are being re-sent multiple times? (Might be, I'm using Windows 8 on a tablet...)

Submitted by NE48-48878 on Sat, 09/28/2013 - 17:31

Well I was finally able to disassemble the carburetor. The jet was NOT quite centered, and I was able to fix that. When I put everything back together, everything seemed to be moving freely, even after the final tightening. (Though at one point, after I had to re-loosen and re-tighten another time, the problem came back. However, just by tightening at a different screw first, the problem went away again, so who knows now?)

I thought I was home free, but the engine still won't start. I know there are several things to try, but there's one piece of information I can't track down: Which way does the rotor in the distributor turn? I have assumed clockwise. I know the firing order, but a lapse in fully documenting the process of removing the old wires means I'm not convinced I put it back together correctly.

Submitted by NE48-48878 on Sat, 09/28/2013 - 17:02

Well I was finally able to disassemble the carburetor. The jet was NOT quite centered, and I was able to fix that. When I put everything back together, everything seemed to be moving freely, even after the final tightening. (Though at one point, after I had to re-loosen and re-tighten another time, the problem came back. However, just by tightening at a different screw first, the problem went away again, so who knows now?)

I thought I was home free, but the engine still won't start. I know there are several things to try, but there's one piece of information I can't track down: Which way does the rotor in the distributor turn? I have assumed clockwise. I know the firing order, but a lapse in fully documenting the process of removing the old wires means I'm not convinced I put it back together correctly.

Submitted by NE48-48878 on Sat, 09/28/2013 - 16:59

Well I was finally able to disassemble the carburetor. The jet was NOT quite centered, and I was able to fix that. When I put everything back together, everything seemed to be moving freely, even after the final tightening. (Though at one point, after I had to re-loosen and re-tighten another time, the problem came back. However, just by tightening at a different screw first, the problem went away again, so who knows now?)

I thought I was home free, but the engine still won't start. I know there are several things to try, but there's one piece of information I can't track down: Which way does the rotor in the distributor turn? I have assumed clockwise. I know the firing order, but a lapse in fully documenting the process of removing the old wires means I'm not convinced I put it back together correctly.

Submitted by NE48-48878 on Sat, 09/28/2013 - 16:59

Well I was finally able to disassemble the carburetor. The jet was NOT quite centered, and I was able to fix that. When I put everything back together, everything seemed to be moving freely, even after the final tightening. (Though at one point, after I had to re-loosen and re-tighten another time, the problem came back. However, just by tightening at a different screw first, the problem went away again, so who knows now?)

I thought I was home free, but the engine still won't start. I know there are several things to try, but there's one piece of information I can't track down: Which way does the rotor in the distributor turn? I have assumed clockwise. I know the firing order, but a lapse in fully documenting the process of removing the old wires means I'm not convinced I put it back together correctly.

Submitted by NE48-48878 on Sat, 09/28/2013 - 15:17

Well I was finally able to disassemble the carburetor. The jet was NOT quite centered, and I was able to fix that. When I put everything back together, everything seemed to be moving freely, even after the final tightening. (Though at one point, after I had to re-loosen and re-tighten another time, the problem came back. However, just by tightening at a different screw first, the problem went away again, so who knows now?)

I thought I was home free, but the engine still won't start. I know there are several things to try, but there's one piece of information I can't track down: Which way does the rotor in the distributor turn? I have assumed clockwise. I know the firing order, but a lapse in fully documenting the process of removing the old wires means I'm not convinced I put it back together correctly.

Submitted by NE48-48878 on Sat, 09/28/2013 - 15:09

Thanks, George. There IS something wrong with the jet. I just noticed that it can't be pushed down with the centering tool. I know I WAS able to before, but I'll have to disassemble the carb now, so please bear with me (unless there's a simple explanation for that, which I doubt).

Submitted by NE48-48878 on Sun, 09/22/2013 - 14:28

Thanks, George. There IS something wrong with the jet. I just noticed that it can't be pushed down with the centering tool. I know I WAS able to before, but I'll have to disassemble the carb now, so please bear with me (unless there's a simple explanation for that, which I doubt).

Submitted by NE48-48878 on Sun, 09/22/2013 - 11:09

Thanks, George. There IS something wrong with the jet. I just noticed that it can't be pushed down with the centering tool. I know I WAS able to before, but I'll have to disassemble the carb now, so please bear with me (unless there's a simple explanation for that, which I doubt).

Submitted by NE48-48878 on Sun, 09/22/2013 - 10:09

Thanks, George. There IS something wrong with the jet. I just noticed that it can't be pushed down with the centering tool. I know I WAS able to before, but I'll have to disassemble the carb now, so please bear with me (unless there's a simple explanation for that, which I doubt).

Submitted by NE48-48878 on Sun, 09/22/2013 - 10:03

The engine was running pretty well, when I bought it. After I got it home, it was some time before I tried to run it again, as I had to get some fuel tank and fuel pump repairs done. After that, it never ran properly. Upon opening up the carb in question, I definitely had to replace the jet. (Old one was seized inside and the diaphragm was useless.) I did not replace the needle as it looked fine. Hope that answers your questions.

Submitted by NE48-48878 on Sun, 09/22/2013 - 09:19

The engine was running pretty well, when I bought it. After I got it home, it was some time before I tried to run it again, as I had to get some fuel tank and fuel pump repairs done. After that, it never ran properly. Upon opening up the carb in question, I definitely had to replace the jet. (Old one was seized inside and the diaphragm was useless.) I did not replace the needle as it looked fine. Hope that answers your questions.

Submitted by SE98-32482CJ on Sun, 09/22/2013 - 07:16

Rick the big question here is was the carb working before it was taken apart for cleaning? Did you change needles? Did you disturb the jet guide? Did you replace the jet?

Submitted by NE48-48878 on Sat, 09/21/2013 - 22:23

Edited on 2013-09-21 22:24:44
The carb WAS apart for a cleaning. I know I don't recall doing anything detrimental to the needle, but it IS possible that I may have set it down improperly at some point. It doesn't LOOK bent, I took another look, but is there a particular technique to guarantee it's straight, other than using a right angle and eyeballing it? And how to center the jet? I have to admit that I purchased a centering tool, but can't find proper instructions on its use.

The spring is on correctly, BTW. And again, it's only on the last quarter-turn of the screw that the piston binds.

Submitted by NE48-48878 on Sat, 09/21/2013 - 22:09

The carb WAS apart for a cleaning. I know I don't recall doing anything detrimental to the needle, but it IS possible that I may have set it down improperly at some point. It doesn't LOOK bent, I'll take another look now, but is there a particular technique to guarantee it's straight, other than using a right angle and eyeballing it? And how to center the jet? I have to admit that I purchased a centering tool, but can't find proper instructions on its use.

The spring is on correctly, BTW.

Submitted by jpgarbani@comc… on Sat, 09/21/2013 - 21:31

I would look closely at the needle. Looks like it sticks when pressure is applied to it by the spring once the cover is closed. Is the needle straight? Is it correctly mounted on the piston? Is the piston return spring correct and mounted as it should?

Submitted by SE98-32482CJ on Sat, 09/21/2013 - 21:29

Rick is this something that has just occurred or is this after a possible polishing and cleaning? I have seen this happen when in the process of polishing on a wheel the dome is deformed by over heating or being dropped. If the carbs were ok prior to the "cleaning" it is this or perhaps the jet needle was bent slightly. If the needle is not bent and the dome has not suffered damage then as Dick said the jet is not centered but this condition would have been there prior. Good Luck.