I came looking for help and it looks like this is the place to get it!
I have a 97 carb model which has been running rough for about 18 months.
e.g. last run of last year I was out- it ran fiine for around 60 miles, then down to 3 cylinders. Through the winter I keep the battery on an optimate and start it once in a while, but its been running on 2 or 3 cylinders.
On 2 cyls now, one & two. can't be the coils? swapped to check. Nope. swapped back. no more fuel in in-line filters, decide to connect teh tank back to front so I can trouble shoot. Guess what, now its cyls 3 & 4 running, not 1 & 2??? I've emptied that tank and dried it. I put a torch in there on a cord and all loooks spotless & clean. I figured the tap. The diaphragm appears to work ok and teh tap is spotless I decided to drill off the cover to see right inside the tap. still spotless. Not I need to tap it & screw back on. but still no evidence of why it swapped sides like that . Any more ideas please?