Mercury 40 Carb rebuild question

[dpal]

Hello,
I have a 93 merc 40 ob 4 cylinder 2 cycle. I have new gasket sets (part number 1395-9651) for both carbs. When I disassembled the carbs, the float bowl had only one gasket on the main jet below and outside the bowl. The diagram shows 2 gaskets on the main jet one outside and one inside.

I am wondering if anyone knows of a reason why someone would leave out this gasket inside the bowl. The gaskets are two different colors one black and one tan but they are both labeled 12 in the diagram.
Thanks

 

[crappiejig]

Re: Mercury 40 Carb rebuild question

Well the confusion may lie with the fact that the diagram is showing 2 different variants of the carb. Look at the body of your carbs and see if you can determine if they are wma-7 or wma-9/-10/ or-13. The -7 is a different creature than the latter carbs,with different jet orientations.

 

[dpal]

Re: Mercury 40 Carb rebuild question

Thank you for your reply,

Both carbs are WMA 9 and the top carb has the barbed outlet for the enrichment (choke) supply and the bottom carb uses the other main jet. All of the diagrams I have found seem to show use both washer gaskets. One gasket is made of a black material like the intake gaskets and the tan one looks more like a cork or paper material. The black one is just a little larger OD.

 

[crappiejig]

Re: Mercury 40 Carb rebuild question

I would think if the carb requires 2 item 12's, then you would have 2 identical gaskets. You obviously have 2 different parts. Maybe another member will have a clearer picture of this, best of luck and please post the outcome of your dilemna.

 

[dpal]

Re: Mercury 40 Carb rebuild question

I think I have the answer,
The Doctor was in. I looked a little closer at a diagram for identifying my carbs. I also scanned the picture and moved the washer gaskets closer to each other for size comparison. It is obvious that the washers are different for the design #4 carb. My black washer is larger. I was informed that the gasket needs to be in there to restrict the flow only to the main jet inlets via the notch.

My float bowls are concave due to the washer being left out and then tightened up. They will have to be straightened carefully in order for the bowl seal to be compressed sufficiently.

This may also fix my high idle RPM problem.

I hope this helps someone in the future.

 

[shannon mc]

Re: Mercury 40 Carb rebuild question

had same problem with 1996 40hp mercury.put one light color one on each side did not have a black one and it fixed my problem of flood ing bad.