My MK2 started up fine but after 10 minutes the 3 front cylinders did not want to work.Only on idle.Dismantled floater and checked brass valve and cleaned.Did not help.As I understand the carburettor dont supply the 3 cylinders with enough fuel. Had the carburettor checked last year and adjusted. Then it was too little in the fuel chamber which resulted in a to lean mixture.I do not understand why this problem appeared suddenly.Piston can be moved,and needle. Pump is ticking normally...New 1.2.3 ignition and the sparks are there, Will now clean the suction chamber..Welcomes Any pieces of advices..advices

 

Problem solved.The cars is running allright again. Porbably some dirt somewhere.I cleaned up the carburettors and the suction chambers. I also remebered a godd tip from my old mechanic how to test fuel spply to an SU carburettor. After removing the suction piston You can see the hole where the needle goes in.There should be fuel standing in the hole.To test supply just blow into the hole so that the fuel goes away(best with light compressed air) Then the fuel level should bounce back lika a fountain.If not there is a trouble either with dirt or the tricky valve in the float chamber(can get stuck).The "new" fuel we have in Sweden does not like old classic cars so You will have to clean the fuelsystem especially after winter hibernation. Now I will also put an extra fuel filter in the system just to be sure.

 

Glad you sorted it, does your "new" fuel have a higher Ethanol level than before, there are comments around the classic car sector that there will be issues with classic cars with the higher Ethanol levels eating some seals and also dissolving some tank coatings, this could lead to many future problems for many.