merc 850 won't fire on bottom cyldrs

[warren/n]

my merc 850 won't fire on the two bottom cyldrs i took the carb off grr! seems ok fuel to carb but still no go loads of spark won't even fire on starting fluied on bottom holes seems to be quite a bit of compression but won't draw fuel in if you take the bottom plugs out and run it on the top 2 and hold a paper towel in front of bottom holes no fuel on paper towel ANY IDEAS wARREN

 

[tashasdaddy]

Re: merc 850 won't fire on bottom cyldrs

well, first never ever use starting fluid on a 2 stroke engine. use premixed gas in a spray or squeeze bottle. sounds like a fuel restriction problem, as the carb float needle is stuck in the closed postion. have the carbs ever been disassembled, cleaned and reassembled with a rebuild kit. no point in doing just one carb. also have you checked compression with a tester.

 

[Chris1956]

Re: merc 850 won't fire on bottom cyldrs

Warren, If you cannot get the bottom cylinders to fire, after spraying fuel into the carb throat, I can only think of two reasons. One is that you do not have enough compression on the bottom two, or much more rare is that the reed valves on the botttom carb are broken.