Johnson 1989 28hp won't open to full trottle & Boggs down

I have a 1989 johnson that had been set up for awhile, run in tank at idle once in awhile, went to start using is and varies problems occured, 1 would not idle, 2, when would run go to give it trottle it would open up to 1/3 th power and then bogg down, so figured it was old gas in carborator that went bad, we soak and cleaned the carborator, then put in a carborator repair kit, then we proceeded to test it out, in water tank it seemed to idle fine with just a small hestiataion, also it would rive up, then we went to test it in the river, the idle was ruff or none, and giving it trottle was about 1/4th, at that point it seemed as it was starving for fuel, we put a new fuel pump on and re-tested, the idle was better, when you went to give it trottle it would then open up as if it was going to run and then it would bogg down sometimes shutting off, can anyone help?

Re: Johnson 28hp won't open to full trottle & Boggs down

Manually clean the high speed jet that is located in the bottom center portion of the float chamber with a piece of single strand steel wire. Solvent just dosn't do the job properly.

Re: Johnson 28hp won't open to full trottle & Boggs down

I used a piece of wire and done what you told me, nothing was changed, it still does the same stuff, won't idle or get full trottle, also I put new plugs in, can it be the plugs and points? also was is the gap on plugs and points

Re: Johnson 28hp won't open to full trottle & Boggs down

Try a compression test and find out where your at

Re: Johnson 28hp won't open to full trottle & Boggs down

Check the compression on both cylinders. What are the readings?

With s/plugs removed, check the spark which should jump a 1/4" to 3/8" gap with a strong blue lightning like flame... a real SNAP! Does it?

Spark gap is .030............. Point gap is .020 .

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubber portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.
NOTE: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

(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.