So yesterday I rebuilt my mercarb (4.3 v6 1989 engine) after dealing with the way it ran for years! Needless to say I should have done it years ago. Boat has always had an off idle roughness and hated running between 1200-1800 rpm. I found some passage ways dirty. Anyways got the carb together and she fired up with just a bump of the key. I adjust the idle and air screw (or fuel screw? Idk) so it’s smooth at idle. Then off to the lake I go.
Get there and the boat doesn’t want to start, I crack the throttle and she fired right up. Rip it around for 20 mins(runs amazing!), shut it off to check for leaks , go to restart 10 mins later, again have to crack throttle and now I need to give it a quick rev or two because it’s stinky Rich.boat clears out and idles/runs perfect again. I m thinking maybe air fuel screw is too far out. I adjust it so it runs a little rough and barely back it out less than a 1/4 turn (out about 1.5 turns). Boat idles steady at 800 , I take it for another spin for 20 mins , shut it off for 20 mins , again I have to crack the throttle then a quick rev to clear it out. Did this a few more times same result.
So the Only thing I changed during the rebuild setting wise was the float level from about 5/8-3/4 (what it was at forever) to the recommended 3/8” which brought the float drop level to a perfect 1-3/32 according to oem kit I bought(running solid needle like before) . I’m thinking lower the fuel level back down in the bowl? I could live with it but Ide rather fix it . Suggestions? Btw I adjusted the choke so it’s mostly open , I run the boat in 80+ temps only .
Get there and the boat doesn’t want to start, I crack the throttle and she fired right up. Rip it around for 20 mins(runs amazing!), shut it off to check for leaks , go to restart 10 mins later, again have to crack throttle and now I need to give it a quick rev or two because it’s stinky Rich.boat clears out and idles/runs perfect again. I m thinking maybe air fuel screw is too far out. I adjust it so it runs a little rough and barely back it out less than a 1/4 turn (out about 1.5 turns). Boat idles steady at 800 , I take it for another spin for 20 mins , shut it off for 20 mins , again I have to crack the throttle then a quick rev to clear it out. Did this a few more times same result.
So the Only thing I changed during the rebuild setting wise was the float level from about 5/8-3/4 (what it was at forever) to the recommended 3/8” which brought the float drop level to a perfect 1-3/32 according to oem kit I bought(running solid needle like before) . I’m thinking lower the fuel level back down in the bowl? I could live with it but Ide rather fix it . Suggestions? Btw I adjusted the choke so it’s mostly open , I run the boat in 80+ temps only .
