'91 merc 40 4 cylinder carb cleaning tips?

G

goldstem

Seaman Apprentice
Joined
Oct 24, 2005
Messages
42
amazing to say that in 35 years I've never had to do a carb cleaning or rebuild. clean living and good filters, and lotsa luck, I guess. well. my luck seems to have run out. What am I in for? Looks like I need to remove the starter motor and oil tank just to get at the carb and probably the fuel pump too. (I'll rebuild that while I'm in there) Any advice, tricks of the trade? if I don't touch the linkages will they still be in sync? I have the factory service manual which says there is a section on syncing the carbs (not the sync to the ignition, but rather to each other) but I can't actually find anything on it..... thanks in advance...
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: '91 merc 40 4 cylinder carb cleaning tips?

Before disassembling carbs, turn the adjustment screws IN while counting the turns. Note the settings so you can return them to their original position. Totally disassemble the carbs soak them in carb cleaner and then make sure every passage and jet is squeaky clean. Use compressed air as a final cleaning. Reassemble with new kits. Kit generally does not include a new float or jets but includes everything else. Set the float according to spec. Before final assembly, tip the carb upside down and blow (by mouth) into the fuel inlet. If air passes you need to check needle and seat and float. If no air passes, reassemble. Lightly seat adjustment needles and then back out the number of turns you noted before you started. Anytime the carbs are removed its possible link&sync can be affected. The key is to make sure the throttle plates are all fully closed and with the throttle lever full forward, the throttle plates should all be perfectly parallel in the throttle bores.
 
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