1982 Johnson 50 improves with every step, but has a hesitation

[bostonwhalermontauk1965]

Hey guys....


Ive been on here asking questions about where to go from here. I pulled out my old 1982 Johnson 50 from hiding and totally re did my 1965 boston whaler from the ground up. I am really happy with how it turned out, except the motor has been very stubborn in coming back to life. Here is what I did and where Im at. For the motor alone, I put in a new water pump impeller, rebuilt the fuel pump and carburetors, and replaced fuel system including a new tank, from front to back.New line, bulb, filter and hoses with fittings.I installed a new engine side wiring harness, because the old one was corroded. I put in new plugs and wires, and the engine has 135 lbs of compression in both cylinders. I am using ethanol fuel, but it is brand new gas and hasnt had any time at all to have water accumulate yet to be the cause of my troubles I dont believe.

It develops an annoying hesitation when opening the throttle on its way up to full speed. I am also not convinced that WOT is really all this motor has to offer. I seem to remember it going a lot faster before. I am at a loss. Is there a chance that the ethanol itself is causing the motor to run like crap? and also, does anyone know how fast a 17 foot whaler should roughly be going at WOT with a 50 horse 2 cycle? Im about to bring this thing to a marine mechanic because I am starting to suspect that possibly under load I am losing ignition. By the way , I tested both ignition wires with a timing light on flywheel on idle so far, and they are firing at the right time. Also the bright blue spark will jump about 3 inches with wire off. Thank you in advance for any ideas - Paul

 

[Haffiman]

Re: 1982 Johnson 50 improves with every step, but has a hesitation

Hesitating is often due to carbs opening a bit too early relative to timing.
Did you get the synch and link right?
Another option might be that your prop is a bit too heavy. What is your max rpm? (above 5000?)
Do a max timing check, try the 'Joe Reeves method'.:
Remove fuel line and drain carbs.
Both spark plugs removed and grounded, or use a spark tester.
Remove throttle cable, use a solid rubber band or similar to hold the throttle lever at engine at WOT.
Crank the engine, set max timing 4 degrees LESS than specified.
Have the muffs hooked up not to ruin the impeller.

 

[bostonwhalermontauk1965]

Re: 1982 Johnson 50 improves with every step, but has a hesitation

Ill bet this is the problem, but I do not know how to synch the carbs to the timing properly. I am following what you are saying with the method, but I am not fully understanding the spark timing adjustment. Right now it is at about 3 degress before top dead center. Thank you for your response. .... Paul

 

[bostonwhalermontauk1965]

Re: 1982 Johnson 50 improves with every step, but has a hesitation

The prop is still the factory one so I doubt that is the problem too.

 

[fireman57]

Re: 1982 Johnson 50 improves with every step, but has a hesitation

You have the same engine that I have and it is on an old '72 steury 14.5ft runabout. Mine will do about 22mph with tow people in it. the boat weighs a ton. I had a hesitation in mine too for a little while so i resoaked and cleaned the carbs real well and put an inline fuel filter in. no problems since. Mine picked up some crud from my old gas tank and would get stuck in the carbs.

 

[retiredfornow]

Re: 1982 Johnson 50 improves with every step, but has a hesitation

Ill bet this is the problem, but I do not know how to synch the carbs to the timing properly. I am following what you are saying with the method, but I am not fully understanding the spark timing adjustment. Right now it is at about 3 degress before top dead center. Thank you for your response. .... Paul

3 degrees BTDC doesn't sound right, not at WOT. Maybe at idle it should be 1 degree. Check Haffimans post again.

 

[larryg]

Re: 1982 Johnson 50 improves with every step, but has a hesitation

sounds like a fuel problem.we need a model number to correctly help you.take carb apart again and clean thoroughly.if this doesnt do it then take a clear fuel line from pump to carb.start it and let it run.see how the fuel is running thru tube.if you notice it not flowing right there is an air leak in one of the lines or the fuel pump isnt pumping properly.