I have a (circa) 1976 Merc 500, 50 OB. Last year (With some great Forum help) I rebuilt the fuel pumps and water pump, and replaced the majority of the disintegrating engine wiring and all of the fuel line components.
It was running fine in a barrel in the driveway, and last week I decided to get it in the water and test it. When I pumped up the primer bulb, I did it pretty robustly to try and verify a good fuel supply, and suddenly gas started squirting out of the top carburetor (There are 2). I knew this was not right, but I fired it up and took it out on the lake. It seemed to warm up fine, and I ramped up the throttle. The throttle seemed to have sluggish response, but the boat planed up and was running really smooth for a couple of minutes. Then, the engine just bogged down to nothing over about 6 seconds and died.
I fairly quickly realized that the engine had flooded out, and that I could only get it started by disconnecting the fuel line. When I re-attached the line, it would flood out again.
To shorten the tale, I determined I had something happening in the squirting carb, and that these things needed to be rebuilt. I pulled off the carbs, pulled off the bowl of the squirting carb, and very quickly determined that the rigid foam float was getting stuck on the edge of the upper carb body...in comparing it to the lower carb, I determined that the upper float definitely had a problem...maybe swelled a little or something, and the hard primer pump must have jammed the oversize float into the upper carb body where it stuck "up".
OK, I am going to change the floats of course. My question is, how far do I really need to go beyond that? I saw absolutely no signs of any gunk, water, dirt, varnish etc in either carb, just pristine gas. As I said, I have already done the fuel pumps. The sticking float appears to definitely be the problem. Do I need to take the carbs completely apart anyway?
It was running fine in a barrel in the driveway, and last week I decided to get it in the water and test it. When I pumped up the primer bulb, I did it pretty robustly to try and verify a good fuel supply, and suddenly gas started squirting out of the top carburetor (There are 2). I knew this was not right, but I fired it up and took it out on the lake. It seemed to warm up fine, and I ramped up the throttle. The throttle seemed to have sluggish response, but the boat planed up and was running really smooth for a couple of minutes. Then, the engine just bogged down to nothing over about 6 seconds and died.
I fairly quickly realized that the engine had flooded out, and that I could only get it started by disconnecting the fuel line. When I re-attached the line, it would flood out again.
To shorten the tale, I determined I had something happening in the squirting carb, and that these things needed to be rebuilt. I pulled off the carbs, pulled off the bowl of the squirting carb, and very quickly determined that the rigid foam float was getting stuck on the edge of the upper carb body...in comparing it to the lower carb, I determined that the upper float definitely had a problem...maybe swelled a little or something, and the hard primer pump must have jammed the oversize float into the upper carb body where it stuck "up".
OK, I am going to change the floats of course. My question is, how far do I really need to go beyond that? I saw absolutely no signs of any gunk, water, dirt, varnish etc in either carb, just pristine gas. As I said, I have already done the fuel pumps. The sticking float appears to definitely be the problem. Do I need to take the carbs completely apart anyway?
