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1990 70HP Lean Sneeze Questions

J

jeffasmith

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"Folks, Thanks for all the hel

"Folks, Thanks for all the help in the past. Last year I was told my motor had a "Lean Sneeze" issue. I had the Carbs rebuilt (as that was the first starting point). This didn't resolve the problem. Noted the main fuel lines had air in them (replaced them with clear lines), also noted the main crank was previously sealed with that orange reddish make your own gasket crap. Swapped out fuel pumps (VRO removed), fuel lines, gas tanks, to no avail. So, I decide the problem was possibly with the main crank seal. Tore it down, and found the upper "O-ring" missing. I replaced the upper and lower O-rings and used OMC Gel Seal II and closed her up with new gaskets. Without the motor mounted and properly water (load) tested, I'm not sure if the problem is fixed (was very hard to replicate without load). There is no longer any air (extremely minimal), a couple of bubbles only in the feed line after shut off, none during idle operation and none in the line to the carbs before or after idling. Would that missing upper O-ring be significant enough to contribute to the lean sneeze? Your opinions are appreciated. I'll get it water tested in a few weeks but, Id appreciate thoughts first! Thanks, Jeff"
 
"air in fuel line,is not causi

"air in fuel line,is not causing the sneeze prob..unless its bad enuf to be running out of fuel in carbs..gaskets leaking,seals leaking,link and sync off,low speed orrices/jets obstructed,are the usual causes."
 
"JWB, Thanks! Would the missin

"JWB, Thanks! Would the missing upper seal (O-Ring) be a prime candidate for the cause? I realize it's kind of a stupid question as who in their right mind would assembly one without it in the first place. Obviously, the previous owner and/or the mechanical butcher did this one wrong. Depending on the amount of throttle, the intervals between sneezing would differ but remain fairly constant. I.e. at WOT every 8 - 9 seconds and about 3/4 WOT every 14 - 15 seconds (based on last years testing) prior to the work done this year. It was dificult at best to ever get it to sneeze while on the ear muffs in the driveway, only under load on the lake. Just some added background info, if it helps.

Thanks, Jeff"
 
"anything,that was not sealed

"anything,that was not sealed as it should be,is a potential area of air intake.once re-assembled,properly,if it still does it,i would examine the reed valves FOR SURE,..intake gaskets,and in the carbs...since it is doing it,at HIGH SPEED,u have/had,alot of air going in where it should'nt."
 
"JWB Marine - Thanks for the a

"JWB Marine - Thanks for the advise, Sure enough I finally got her out on the water yesterday and no more "Snezzing" So between the missing o-ring on the upper main bearing and the improper seal of the crankcase, the problem was solved. I thank you and all with this discussion board for the valuable information and advise. Another happy boater back on the water!

Jeff Smith"
 
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