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Merc 15hp carb cleaning circuit question - is this a dead end or just plugged?

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steveg_nh

Regular Contributor
I have a 2002 Merc 15hp 2 stroke. Serial Number 0T533347, Model 1015201ZD

It wasn't idling well, so I pulled the carb, disassembled and cleaned it very well. All came out great. All circuits are clear and all varnish gone. There is one circuit though, that I'm just not sure of. In the carb bowl, near the top. I have tried everything to figure it out, but all the carb cleaner and compressed air in the world doesn't seem to be showing me where the other end of that hole is (the tube I call the circuit). Is that an actual open circuit? Or just a hole with a dead end? I don't want to put the whole carb back on and find that is still plugged and causing grief. It appears to go into the primer (choke) assembly, so I'm thinking it has something to do with giving more gas to the motor when choking, but maybe I'm wrong. Here's a pic of the bowl with the hole in question circled. Any help is appreciated. I'm pretty good with carbs and cleaning them (2 stoke snowmobiles, small yard tool engines, etc), but this has be stumped.

Thanks!

carbbowlmerc.jpg
 
do you mean just full the bowl while off the carb with gas and operate the plunger? If that is clogged though I won’t see anything will I?

it really looks like a circuit just can’t see it’s exit.
 
That hole is a vent for the primer bowl. The primer bowl fills through the
round check valve that is also in your picture. As the primer bowl fills,
the air has to go somewhere. There is a little hole at the top of the
primer bowl that leads to little hole you have circled. If you spray WD-40
into the hole that you have circled, you should see a tiny amount come
out at the top of the primer bowl. It is just a little tiny air passage!
 
whitegreg56 said:
That hole is a vent for the primer bowl. The primer bowl fills through the
round check valve that is also in your picture. As the primer bowl fills,
the air has to go somewhere. There is a little hole at the top of the
primer bowl that leads to little hole you have circled. If you spray WD-40
into the hole that you have circled, you should see a tiny amount come
out at the top of the primer bowl. It is just a little tiny air passage!
Click to expand...

This is great information, thank you! I will check for that. If it's very small, maybe I missed it.

One more question too. After looking at some parts diagrams, I began to wonder if the carb to engine gasket was missing. I ordered a new one, just in case, that looks like a paper gasket that covers the entire mating surface. Part number 27-192061 from Mercury. Here's a pic of the mating surface with some type of rubber gasket material outling some of the areas. Is this a gasket, and I don't need the 192061 gasket? Or was it in fact missing and what I'm seeing (the picture) is supposed to be there along with the proper gasket? Thanks!

Carb_gasket.jpg
 
The rubber lines are there to provide some extra sealing when the mounting nuts are tightened down.
Your new gasket will probably have the same rubber lines.

It's a good idea to use a new gasket every time the carburetor is removed.
So, remove what is there. Should be clean metal on both sides. Install new gasket making sure you have the correct orientation.
Mount the carburetor on the studs and tighten the mounting nuts.
 
Thanks. I have the new gasket. Arrived today. But no rubber on it at all. Just that paper like gasket material. Should I leave the rubber on the engine then and just install the new gasket. The rubber on the motor looks factory like it’s not made to come out/off.
 
steveg_nh said:
Thanks. I have the new gasket. Arrived today. But no rubber on it at all. Just that paper like gasket material. Should I leave the rubber on the engine then and just install the new gasket. The rubber on the motor looks factory like it’s not made to come out/off.
Click to expand...

Getting back to finishing this up but now sure what’s best to do with the rubber on the engine given I don’t see anything similar on the new gasket.

Any advice? Thank you.
 
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