Carb float adjustments....

jwitty

Member
So on my B, I get this sputtering and black smoke with a load. Could this be caused by the float being adjusted too high and letting fuel go up the main jet? What is the proper setting for the float. (Not sure of carb model off hand, but it's a 51)
 
Usually one turn out on the load mixture needle.
Fine tune from there.
Should be open enough to pull smoothly under load, no black smoke,
Except for a puff on sudden acceleration.
 
(quoted from post at 23:17:40 11/16/17) Usually one turn out on the load mixture needle.
Fine tune from there.
Should be open enough to pull smoothly under load, no black smoke,
Except for a puff on sudden acceleration.

I've adjusted the load needle every which way. I've run the tractor with the intake off so you can see the choke plate, and it is opening fully. Still get black smoke. I can usually only have the load needle set between 1/4 and 1/2 turn out otherwise it's not enough fuel or way too much and it starts blowing a lot of black smoke and hesitates, even at the standard 1 turn out.
 
Easy to check the float level without removing the carb. Just turn off the fuel, remove the carb bowl drain and screw in a fitting with about 6 or eight inches of clear tubing attached. Hold the hose up beside the carb bowl and turn on the fuel. The fuel in the clear tubing will be at the same level as in the carb. It should be 3/4 inch below the carb bowl gasket.
 
Jwitty,
Could be your float has developed a hole and your float isn't floating or you have a piece of crap under the needle valve not letting it shut off tight. Try shutting the fuel off at the bowl and see if it runs better just before it runs out of gas. That will prove a float issue if there is one. Could be just a plugged carb or even ignition problem Good Luck .
John
 
(quoted from post at 09:15:20 11/17/17) Jwitty,
Could be your float has developed a hole and your float isn't floating or you have a piece of crap under the needle valve not letting it shut off tight. Try shutting the fuel off at the bowl and see if it runs better just before it runs out of gas. That will prove a float issue if there is one. Could be just a plugged carb or even ignition problem Good Luck .
John

I've torn the carb apart to clean it and there was no fuel in the float, so that should be fine. I know this has to be with the carb because I've been through the ignition and it gets great spark all the time. And I know it's not a blockage in the intake since I ran it without the air cleaner hooked up. And the choke plate is opening fully. The only other thing I could think of is that the float is just a little higher level than what it should be, but idk if that makes it run so rich because its not flowing out of the carb....
 
Sounds like it has some sort of obstruction, likely in one of those tiny ports. I'd give it a drink of seafoam and run it a while before I tore anything else apart.
 
That should have a DLTX 67 on it. Actual float level (not fuel level) is 3/8 " from bowl edge to float with bowl upside down. Fuel level is 1/2" from top of bowl (using fluid & tube method) (67 and 71 only) Sounds like you have a cracked stem or stem threads have been repaired and there is a leak of un-metered fuel getting into load nozzle. Also , there could be an obstruction in the bowl vent passage that is in behind the two little round brass baffles in top of bowl in this carb. You have to pry them out and there is a little vertical passage in behind them . You should be able to shove a spray can straw up that passage at least an inch or so. If this is plugged or even partially, it will cause fuel to be forced up through load needle seat and into nozzle and out nozzle vent and out front of carb which would smoke. If carb doesn't have these baffles then it's wrong carb or they are missing. Pic of carb will verify this.
a178426.jpg
 
Jtwitty, seems like you're trouble shooting...glad to hear the intake was not blocked....now take the carb off and turn upside down...blow into the fuel inlet and see that it blocks off air upside down...it it does your seat is working fine...now take the float out and submerge it in gas and hold for a while and see if it bounces back...with no extra weight...if it does then your float is okay....now take a torch and remove all the small screws...heat and let cool and then you can remove the screws...remove the main nozzle...then rod out all the passages....reassemble....set float to factory specs and see what it does...keep up the trouble shooting...not easy but be persistant....
 
Yes there is. Length and the load has short steep little angle on end and idle has long tapered angle. They don't interchange.
 

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