Logo
FULL SITE MENU

1993 6hp Johnson loses power when warmed up.

V

v8George

New member
Hi, I have a 93 6hp 2 stroke outboard on a 10' pvc dinghy typically used as a tender in salt water.
I ran it really hard all day a few weeks ago at WOT bouncing around the bay. On the last leg of the trip, it dropped power dramatically, like 50%.
The engine was still showing water streaming out the back but smelled really rich and stinky, like when an old car drives by running modern gas.
It runs great when cold, then gets warm and drops power. I pulled the t-stat out and it's pretty crusty so I ran it without one with no change. Both cylinders have spark and I have 110 lbs on compression in each cylinder. Does this engine have some sort of limp mode?
I am planning on swapping in a new water pump and t-stat but I am not sure what else to check.
Thanks
 
No limp mode.----Does spark jump a gap of 3/8" ( 1 cm ) on both leads ?-----Possibly a bad float / float valve in carburetor.----Hole in fuel pump diaphragm.----Good idea to put new impeller in every 5 years.
 
It's looking like a bad coil or CDI box. I ran it this morning and both plug wires tripped the timing light. I waited until it started chugging and found that the bottom cylinder lost spark when warm. The timing light wouldn't pulse. I pulled the bottom plug wire while running and no change. I plugged it back in and pulled the top plug wire. As soon as i pulled the top plug wire, it stalled. I am going to swap coils and re-test to isolate whether it's a coil or cdi.
 
Let us know how it goes.
I had similar issue on my '71 but it's got points. Super-cleaned the carb and the problem went away.
Sounds like your troubleshooting game is top-notch!
 
you might check the plugs just to make sure they have continuity i know its a long shot but might save ya some money if it is the plug
 
Are you flushing the seawater out of the motor regularly, rinsing it off, greasing, and spraying down with an anti corrosive? I have sold many small motors to be used in seawater. They need to be cared for. Sounds like evidence of impending doom, as your thermostat was crusted. This may be a difficult motor to ever replace with something as dependable, economical, powerful, lightweight, and AFFORDABLE!
 
I put the new CDI in today and ran it in a trash barrel for a while. That seems to have fixed the problem. I'll sea trial it next week but so far so good. I also bought a water pump kit and I'll put the thermostat back in it as well.
 
Back
Top