How critical is the carburetor float height?

[bowfisher8967]

I'm rebuilding the carb in my mercury (first time doing this), and the service manual says the float height needs to be 15.5mm plus or minus 1mm. I measured my float height at 19mm. How critical is the difference? It says "if height is not correct, then replace," but it is a brand new float and new needle valve, so i'm lost.... Unless the service manual i'm reading is not the correct one for my motor. My serial number is 1B281020, and the service manual is "0G590000 and up."

 

[canoemang]

Re: How critical is the carburetor float height?

I would follow the spec's given to you by the manual. Float height is very important in regards to if you get it wrong and the cylinders/carbs flood or run dry and starves for gas causing the motor to run lean then burn up a cylinder.

Can you adjust the float level and get it to the within spec?

 

[jerryjerry05]

Re: How critical is the carburetor float height?

Motor and HP?
Post pics of the float.Some are adjustable.
I worked on a boat and the floats had NO adjustment and they leaked like a collander.
It's actually easy to set the height and drop.Get the factory manual.J

 

[Faztbullet]

Re: How critical is the carburetor float height?

Make sure that the needle is in the slot on float and not riding on top of it, as this will throw measurement off. Also make sure it a OEM kit and not a aftermarket as I have returned 10 aftermarket kits for Yamaha that had wrong length needle in kit. If every thing checks out replace the float as it is non adjustable plastic....

 

[bowfisher8967]

Re: How critical is the carburetor float height?



Here's the pics. Sorry bout the quality. Its a 15hp mercury 4-stroke S#: 1B281020. I did make sure the needle is seated, and i'm 99% sure this is the correct kit (I looked up the part number myself and ordered from a dealer). So I just dont know.... I agree that it should be at the correct height, but this is a brand new float and needle and I dont see any way to adjust it.....

 

[bowfisher8967]

Re: How critical is the carburetor float height?

Well, right after posting this one above, I realized my error, and found a solution to the problem. So embarassing to mention here, but for the sake of anyone looking at this post for help in the future, just be sure to use the METRIC side of your ruler... heheh. :facepalm:

 

[Fun Times]

Re: How critical is the carburetor float height?

Unless the service manual i'm reading is not the correct one for my motor. My serial number is 1B281020, and the service manual is "0G590000 and up."

http://www.justanswer.com/uploads/ROCKETBOAT/2008-12-26_230711_3b.pdf

After further review Gerry, I believe you are correct. Above is the link for the carburetor section of service manual 90-856159R02 SEPTEMBER 2002.

9.9/15 FourStroke (323 cc)
9.9/15 BigFoot FourStroke (323 cc)
(U) 0G590000 and Above
90-856159R02
September 2002
Service Manual.

What was confusing was when running the o.p's S/N it came as,
15/20 FourStroke
(U) 0R235168 and Above
90-899987
November 2008

Service Manual
90-897347A01
July 2008
Color Diagram Assembly.:facepalm:

 

[carholme]

Re: How critical is the carburetor float height?

Mercury is saying that the service manual for your engine is P/N: 90-856159 which I presume is the one you have.

From here:

http://www.mercurypartsexpress.com/ca/parts-search.html#epc::mc3231865mr1031ar1839

As well, your s/n is a model:

1F15203FD MERCURY 2006 15

Parts listing:

http://www.crowleymarine.com/mercury-outboard/11805.cfm

Under "Service/Support Material" you will see the manual 90-856159 listed.


Gerry