1973 Johnson 25hp runs only with choke on.

Hello

I'm new here, and I have some major issues I need help with.

first let me explain totally what is going on and what I have done.

I first of all just rebuilt my Carb because of poor performance. I use an original Carb rebuild kit I also replaced the Slow speed needle.

Here is my first problem the motor will only run with the choke closed all the way, and dies when the chock is opened. Now if i turn the slow speed needle all the way out many turns away from the initial 1 and 1/2 turn setting I am able to run the motor with out the chock but it dies as soon as the speed is increased.
Now today I checked all hose connections, and gaskets, as well as the fuel pump, and all lines for leaks thinking that an air leak is making the choke over compensate. I found nothing.

Now here is the real puzzle. As meticulous as I am, when I took the carb apart I also removed the core plugs. when I did this I replaced them however I don't remember if I removed three plugs or two. The reason I ask this is because I put three back in and one plug over a hole that is in the inside of the carb under the float valve(see picture) but I'm not sure if I was suppose to do this. The kit came with four plugs so I assume the kit is for other carbs.

Now the exploded view in the original parts manual shows no plug going inside the carb body under the float. What I need to know is if anyone knows if there are more then 2 core plugs on my carb, or if there is in fact a plug that goes in the hole under the float. As you can see in the picture there is two holes in the bottom and one is open the other has a plug, although the exploded view and parts manual has no part for the plug. Is this plug suppose to be there?

Re: 73 Johnson 25hp runs only with choke on.

im pretty sure you need the other plug every carb ive seen has another plug where yours is missing without that plug your drawing to much air in return not letting all the gas flow through the carb

Re: 73 Johnson 25hp runs only with choke on.

The hole on the left side of your graphic is a float chamber vent hole. DO NOT plug that hole. That should be obvious as there is no way to seat a core plug in that location.

Manually clean the brass high speed jet located in the bottom center portion of the float chamber with a piece of single strand steel wire.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.
When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.