1991 225hp intake manifold has small hole behind carb

[phatmanmike]

1991 225hp . been having problems with sneezing back through the carbs. i was told its a lean condition. anyways...<br /><br />i removed all 6 carbs and all fuel lines and also the intake manifold and reed valves. upon inspection of reed valves, i noticed a small hole behind the top starboard carb in the intake. its a machined hole that looks factory in appearance. this hole bypasses the reeds, and i saw sparking through the carb one day and thought that the reeds were bad, which turn out are A-OK. this hoile is very small, maybe only a 16th or even 32 of an inch in diamater and only this carb hole has it, none of the others have this<br /><br />i ordered a shop manual, but untill then, does anybody know what this hole is for?

 

[seahorse5]

Re: 1991 225hp intake manifold has small hole behind carb

vacuum from #2 intake manifold is used to "pull" oil residue up from the bottom main bearing, up thru the oil line check valve, then to the upper main bearing. This provides lubrication to the main bearings on the crankshaft.<br /><br />If the lower crank seal starts to leak, you will find water in #2 cylinder or on the sparkplug.

 

[phatmanmike]

Re: 1991 225hp intake manifold has small hole behind carb

i dont understand how this hole could"pull" anything.... its not connected to anything, any tubes or hoses what so ever. it simply goes through the intake manifold from the carb side and out the other side...<br /><br /><br />maybe im missing something