Carb Float Adjustment

[dblanton]

Does anyone know what the carb float adjustment (settings) should be on a 75hp 1981 Evinrude. Fuel is bubbling back up into the throat of the carb and running out while idling on the muffs. I rebuilt the carbs and only having this problem on the bottom carb. I was told that the float is out of adjustment.

 

[tashasdaddy]

Re: Carb Float Adjustment

i may be wrong, but the rule of thumb is when the carb is turned up side down, the float should be in line with the carb body.

 

[R.Johnson]

Re: Carb Float Adjustment

The problem is more than likely the float needle, and seat leaking. Did you replace these part's. As in the other post, the float should be parallel with the carb body when held upside down.

 

[dblanton]

Re: Carb Float Adjustment

Yes the needle and seat was replaced when the carb was rebuilt.

 

[R.Johnson]

Re: Carb Float Adjustment

Was that a Sierra carb kit by chance.

 

[dblanton]

Re: Carb Float Adjustment

I bought the kits on line at ishopmarine.com packaging did not have Sierra printed on them.
All three carbs were rebuilt at the same time, top two carbs are working fine I'm only having a problem with the bottom carb. I took the carb off and took it apart, gave it a through inspection and could not find anything that looked wrong, I adjusted the float a little higher to close the needle a little sooner but that didn't help, still have the same problem with the bottom carb.

 

[kynolan2183]

Re: Carb Float Adjustment

Check that the little spring that holds the needle in place is not getting in the way. I had that happen once where the spring was touching the hing pin and caused all kinds of problems. Also check that your timing and link and sync are correct. If your timing is off then you could have problems. I just went through that with mine. Also check that the float is not damaged causing it to be heavily soaked with fuel. Don't run it with the carb set leaner as you have done. The bottom piston is the weak link in the three cylinder.

Kyle

 

[gazza2007au]

Re: Carb Float Adjustment

u dont bend the float up u bend it down so when the carby fills the float is lower putting more pressure on the needle to seal the seat by bending the float up your allowing the pin to release more fuel with a higher float level
or your problem could be a gravity problem were u running the motor while the fuel tank was level or a tad bit higher than the over flooding carby your talking about?

 

[dblanton]

Re: Carb Float Adjustment

Thanks everyone for your advice, I've tried reajdusting the float, again everything looks good but it's still not fixed. At this point I am thinking about giting another carb kit and go through the rebuild process again.

 

[Silvertip]

Re: Carb Float Adjustment

There is only one way fuel can get through the engine and it must pass through the inlet needle and seat. So either the float is adjusted wrong or the inlet needle is not seating. To test this, simply invert the carb and blow into the fuel inlet. If you can blow through the fitting the inlet needle is not sticking. If not, its working ok but the float level may not be correct. Lowering it shuts off fuel sooner as was pointed out.

 

[Silvertip]

Re: Carb Float Adjustment

Dang fat fingers. Should say "inlet needle is not SEATING".

 

[gazza2007au]

Re: Carb Float Adjustment

also make sure when u rebuild the carbys that you remembered to put in the seat washer u could have a leaking thread?

 

[wreckless]

Re: Carb Float Adjustment

Float adjusted too high. When holding the carb upside down the bottom of float should be parallel with carb base. When holding carb in normal (upright) position the carb should drop approx 3/4 inch down measuring from bottom of carb body to top of float. Also, when you rebuilt carbs did you replace or thoroughly clean the upper and lower orifices?

 

[dblanton]

Re: Carb Float Adjustment

Hey all thanks for all the advice. I checked the float adjustment again still looks good, float drop within specs, I did check the seat valve again by removing it then blowing compressed air through it I checked the needle with a magnifying glass the tip is good which I suspected it to be since I replaced the needle and seat when I rebuilt the carb. I did notice that the seat valve was not very tight when I removed it, when I reinstalled it I tightened it down more, put the carb back together and with the carb upside down so the needle would be seated I tried blowing through the fuel inlet, the needle is seated as it should be no air escaping, I turned the carb up right so the float would drop then back over and tried blowing through the fuel inlet, again no air escaping. I will install the carb and start it up to see what happens. I am hoping that tightening the seat valve more did the trick. By the way I did not blow compressed air through the fuel inlet just the air out of my lungs.

 

[gazza2007au]

Re: Carb Float Adjustment

leaky seat thread would have been your problem sounds as if u have fixed it good stuff 8)

 

[iwombat]

Re: Carb Float Adjustment

A little trick I learned from rebuilding bikes is to take the old float needle and coat it with fine valve lapping compound. Then use a set of needlenose pliers with the old valve and lap the seat. The seat can start to oval out over time and that little trick can bring them back into round.

Be sure to clean it out thoroughly with carb cleaner and a good soak afterwards.

 

[dblanton]

Re: Carb Float Adjustment

Hey everyone just to let you know the carb is fixed, it turned out to be the seat valve was not as tight as it should be and fuel was leaking past the threads.
Now I have to go through the sync process again.
Thanks again for all the good advice.