idling problems on 1972 50horse johnson

[darren2]

I am having some problems getting the idle to stay consistant on my motor. I have several times adjusted the idle according to the specs in my driveway with the cups on. Then when I take it to the lake it is idling so high I am afraid to put the motor in gear.I usually will spend another 30 minutes adjusting it again on the lake. any help would be greatly appreciated

 

[12Footer]

Re: idling problems on 1972 50horse johnson

Welcome to iboats, Darren.<br /><br />First check for water or debris in the fuel system. It will condense in the tank, inline filter, and the carb bowls.<br /><br />If you are sure the fuel delivery system is free of contaminants, next step is to check the compression. The fuel will be delivered inconsistantly if the compression is low.<br /><br />Good compression? Check the fuel pump and rebuild if needed. (you might want to anyhow, as the diaphrams are eaten alive by alcohol "enhanced" fuels).<br /><br />Getting a steady flow of good, clean gas? Check for corroded contacts at the switchbox,coils, plug wires ect.<br />Also change plugs if the ones in it look bad, or have greater than 80 hours run time on them (normal interval for changing).<br />While yiou have them out, look for an overly clean looking plug.This generally indicates water in the fuel, or the water jacket leaking into the cylinder (head gasket or exaust manifold gasket).

 

[wilde1j]

Re: idling problems on 1972 50horse johnson

Idle is best adjusted with the boat in the water, although I'm surprised the idle increased from the hose adjustment ... it's usually the other way around due to back pressure.

 

[karlp]

Re: idling problems on 1972 50horse johnson

I had the same experience with my 1978 70HP Johnsons. I did a number of things so I do not know which one solved the problem. First I cleaned out the idle jets in the carburators. It took me a while to remember that each carb has a high speed jet and an idle jet. Next I found that the trailer allowed the boat to flex differenly that the boat did in the water and would put different tensions on the throttle cables. To adjust the idle on the trailer I would loosen the cable clamping screws at the engine and make the adjustment. Afterwards I made sure that I took out all of the slack in the throttle cables with the adjusting screws on the cable and rechecked the idle.