i have an older merc m500 serial #1569621 thunderbolt ignition and aj54a carb's when the motor is running with no load (on flush attachment ) appear's to be running fine but when there is a load put on the motor it loses power does anyone have any info that might help me get started. i have also replaced all 4 plug's and it appears to have a good spark could it be a fuel problem within the carb's , fuel pump (if fuel pump problem could it be hooked up to an electronic pump ) or could it be in the ignition somewhere? i'm fairly mechanicly inclined but i know absolutly nothing about these motor's any help would be greatly appriceated thank's

rebuild the carb and new fuel pump

ok thank's i'll give that a try and see what happens would u know where i might be able to get a carb kit for that year i think it's a 63 if my numbers are right. also i noticed after a better inspection it look's like a couple of plug wires are pinched quite bad would anyone have any idea if i might be able to fabricate some other sort of plug wire to work in it's place thank's again for the the help