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Bottom Carb Blowing Gas

Same motor that wouldn't fire on 3 and 4?

Gas blowing out the throat is almost always busted reeds (which would have also accounted for 3 and 4 not firing) - that really sucks on this model - have to split the block....

And cylinder compression has nothing to do with the crankcase - so yes, can have 125 lbs at the (head) and a big "hole" in the crankcase....
 
galamb said:
Same motor that wouldn't fire on 3 and 4?

Gas blowing out the throat is almost always busted reeds (which would have also accounted for 3 and 4 not firing) - that really sucks on this model - have to split the block....

And cylinder compression has nothing to do with the crankcase - so yes, can have 125 lbs at the (head) and a big "hole" in the crankcase....
Click to expand...
Well put and dead on as always...jb

Ps, if you keep cranking on it you won't have compression in 3-4 for much longer.
 
Buy a manual from this site, please.

Fixing this motor is not that hard, and do NOT pull the crank assembly all the way out (or you'll have to stuff the pistons back in--not fun). Move the crank assembly just enough to remove the bad reed cage.

Jeff
 
factory manual is the best, other manuals are available. Neither will tell you what is really wrong, this is where experience comes in. If fuel is spitting out you have a major problem, unless there is a twig/crap in the reed. Did you remove the lower carb and have a look yet?
 
Yes, definately need, at minimum, a Seloc's manual but would be better off with a Merc factory manual (even though it's about 80 bucks compared to the $35 for Selocs).

And as Jeff notes, you don't have to completely pull the crankshaft out to get at the combination main bearing/reed cage, but there is a ton of stuff you do have to remove (including the flywheel, a good chunk of the ignition system, linkages etc, plus anything in the way of the crankcase bolts).

So alot of work on many different components just to get at one relatively small/easy to fix problem.

You will also need to replace any seal or gasket you disturb in the process (which is where the factory manual is superior in identifying, by part number, everything you have to touch or replace).

This is not a little job but it's not rocket science either. And if you are thinking "maybe a shop should do this", you can get some quotes but if you hear numbers approaching the 1000 dollar range that wouldn't be surprising...

And if ultimately you find that the lower reeds are stuck, the cause of that "came through the carb" in the first place - so "just because" I would clean and rebuild the carbs - otherwise you could be doing it and another reed job in the not so distant future...
 
galamb said:
Yes, definately need, at minimum, a Seloc's manual but would be better off with a Merc factory manual (even though it's about 80 bucks compared to the $35 for Selocs).

And as Jeff notes, you don't have to completely pull the crankshaft out to get at the combination main bearing/reed cage, but there is a ton of stuff you do have to remove (including the flywheel, a good chunk of the ignition system, linkages etc, plus anything in the way of the crankcase bolts).

So alot of work on many different components just to get at one relatively small/easy to fix problem.

You will also need to replace any seal or gasket you disturb in the process (which is where the factory manual is superior in identifying, by part number, everything you have to touch or replace).

This is not a little job but it's not rocket science either. And if you are thinking "maybe a shop should do this", you can get some quotes but if you hear numbers approaching the 1000 dollar range that wouldn't be surprising...

And if ultimately you find that the lower reeds are stuck, the cause of that "came through the carb" in the first place - so "just because" I would clean and rebuild the carbs - otherwise you could be doing it and another reed job in the not so distant future...
Click to expand...

Thanks to everyone for all the great advice. Atleast now I know what's wrong. Thanks!
 
HI there, I realize this is an old thread, but if anyone is still watching, I have a similar problem, maybe the same. I am getting puffs of white smoke from my bottom carb. If it is gas, it is being combusted before it makes out out of the intake. I suspected before that it might be the reeds. Thoughts? I am planning to do a full rebuild this winter and hopefully will find the problem.

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1990 Johnson 175 V6 VRO
 
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