Johnson 50HP (Late 70's?) bogging at full throttle

Hey there,

Been having troubles with the outboard since the boat was put into the water this year. As the title states, get to anything more than 1/2 throttle and it'll start to bog out. Will start fine and idle properly.

Here's what's been done....
- tried 3 different fuel tanks and lines to the motor (one from a friends boat with a new primer bulb, which is definitely working properly) with no change in the problem.
- All fuel lines lines within the motor were removed, blown out and reinstalled. One line (from carb to carb) was replaced as it looked to have a tear in it.
- fuel filter screen cleaned out
- rubber gasket for fuel filter looks in good condition
- while running, tried pumping primer bulb with no change
- while running, tried pulling choke at full throttle with no change
- changed out the plugs with new ones
- new gas
- tried with gas tank cap cracked and screwed on tight

At a loss of what to try next, sure does seem like it's starving for gas ????

Does anyone have any tips as to where to go from here?

Thanks in advance!!

Re: Johnson 50HP (Late 70's?) bogging at full throttle

it's time for a complete carb cleaning and rebuild kit with new float. tear them down completely, soak all metal parts in carb cleaner overnight. plastic parts clean with spray cleaner, then take a small wire and run it thru every orifice. blow out with compressed air, and reassemble using a new kit and float. set you low and high speed jets, setting instructions are in the engine faq forum, by joe reeves the best.

Re: Johnson 50HP (Late 70's?) bogging at full throttle

tashasdaddy said:

it's time for a complete carb cleaning and rebuild kit with new float. tear them down completely, soak all metal parts in carb cleaner overnight. plastic parts clean with spray cleaner, then take a small wire and run it thru every orifice. blow out with compressed air, and reassemble using a new kit and float. set you low and high speed jets, setting instructions are in the engine faq forum, by joe reeves the best.

Click to expand...

Thanks for the advice. Can you suggest any good online suppliers for a carb kit or should I rely on the local Evinrude dealer? (assuming there is one )

Re: Johnson 50HP (Late 70's?) bogging at full throttle

maxrules.com laingsoutboards.com ishopmarine.com iboats store. remember a new float with each kit. the get gas logged and don't float right.

Re: Johnson 50HP (Late 70's?) bogging at full throttle

Found another problem that may be related to the bogging.

After some more testing, it was noticed that the motor seemed to be missing quite a bit. Seems that one of the cylinders is firing sporadically.

Checking the spark on both the wires, one is noticably poorer than the other. Is it a possibility that the ignition parts could be causing this bogging?

Re: Johnson 50HP (Late 70's?) bogging at full throttle

If you've cleaned your carb, etc. check to see whether your carb has high speed mixture settings? If so, it may be set too lean.

Re: Johnson 50HP (Late 70's?) bogging at full throttle

When you say that one spark is poorer than the other I take it to mean that one has a bright blue spark that snaps and the other has a yellow or orange spark. Blue is good, yellow pulls a vacuum. Remove your ignition coils and clean the grounds well then when you put them back on swap positions. If the weak spark follows that coil then it is back and replace it.