Mercury 40 HP Carburetor Jet?

billaustin3

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Nov 22, 2017
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I removed the carburetor from my 1982 Mercury 40 HP outboard this afternoon. After removing the cover from the float bowl, I noticed there was a small brass nut with a hole through it on the side of the float bowl cover. The MarineEngine website identifies this brass nut (item number 10 on their parts list) as a Jet with either a .092 or .096 hole in it. Unscrewing this jet revealed a passage that connected directly to the float bowl and also to another connection where the economizer hose connects. It was very apparent by marks on various screws this carburetor had been disassembled in the past. Was there supposed to be something under the jet? I can't find anything identified on the MarineEngine website that shows something is supposed to be there? It appears to me that if the float became stuck, gas would just run out of the jet all over the motor.

Thanks,
Bill Austin
Saint Marys, GA
 

racerone

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Dec 28, 2013
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Serial # of the motor?---Do you understand the concept of the economizer and how it and a carburetor works ?----Running issues with your motor ?---Why are you working on this carburetor ?
 

billaustin3

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Nov 22, 2017
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Racerone, I will attempt to answer your questions. The serial number of this motor is 5993966. I recently acquired this outboard motor and it was not running when I acquired it. After an examination of the fuel in the tank the previous owner had used with this outboard, I discovered there was water in the tank along with dirt and debris. In addition, one of the previous owners had removed the internal fuel filter. An external fuel filter had been added to the fuel line, but it was clogged up. Therefore, I decided to rebuild the fuel pump and carburetor. I have worked on many carburetors throughout my life. I own four other mercury outboards, KG7, KH7, Mark 30, Merc 800. This is my first experience with an outboard carburetor that has an economizer.
 

billaustin3

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Nov 22, 2017
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Wanted to give everyone an update on the 1982 40hp Mercury outboard. I rebuilt the fuel pump and the carburetor. All fuel line inside of the cowling was replaced. The fuel pump actually looked OK before the rebuild. There was some small bits of debris in the carburetor. After reassembly, and using a new external fuel line and fresh marine gas with quicksilver synthetic blend oil, the Mercury fired right up and ran like a top. You can't beat a Mercury!!!

I also conducted an internet search, including a search of this website, for information on carburetors with economizers. I could not find any information on this subject except to find this type of carburetor mentioned in other post. If anyone knows how they work or what the purpose of an economizer is, I would appreciate hearing from you.

Best Regards,
Bill Austin
Saint Marys, GA
 

racerone

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Dec 28, 2013
Messages
36,043
It is a crude method of lowering / controlling atmospheric pressure on the fuel in the carburetor bowl.----As pressure is lowered , less fuel is delivered to the air flowing through the carburetor.
 
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