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1989 johnson 28hp wonbt stay running at high speed

B

BRSBOATER

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"I am about to go crazy..Compr

"I am about to go crazy..Compression is 105/110 on cylinders. I have rebuilt the carb..It will start right up and run but when I go to give it gas for high speed it will run for a while then shut down..if I press the chock button it will run for a while..if i keep doing that at mid speed it will keep running....I put a new carb kit on..new needle, new float, new gaskets..blew it all out with air hose...put new sparks plugs in....I have changed the position of the float about ten times..last time was burning to rich..gas was comming out the carb. Thank You for your Help/Suggestions Brian"
 
"Brian,
I can only think of t

"Brian,
I can only think of two things off hand that you may have missed.

One is did you remove the main jet and clean it with a torch tip cleaner? (take care when doing this not to remove any of the jet material)

The second is the fuel pump can be getting weak or is pulling air into the system at some point.

Of course being an outboard it very well can be another problem that is acting as if it is fuel related.

It's a good idea to check the condition and gap of the points and check the coils for any cracks that could be arking to ground if you haven't done this.

Just a few thoughts.

Good luck"
 
"The fact that you can keep th

"The fact that you can keep the enine running by operating the choke would indicate the problem is fuel related.

(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.

If pumping the fuel primer bulb eliminates the problem, and no obvious fuel leaks exist anywhere, suspect the fuel pump. Fuel leaks would cause the fuel pump to draw air.

If you did not manually vlean the high speed jet that is located in the bottom center of the float chamber, do so.

(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: 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.

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."
 
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