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Johnson Dies at Full Throttle

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gippy469

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I have an 1994 Johnson 88 SPL that dies at full throttle, not a stubble and cough, but dies like someone pulled the kill switch. I suspected a fuel problem originally and have been through the carbs, rebuilt the fuel pump, replaced fuel line and primer bulb. Last out on the bay I tried pumping the primer bulb continuously at wot and the motor still cut out after about 30-45 seconds. motor idles great and will run good at slower speeds. After the motor dies it will start up again easily but revs (4500+ rmp) on restart. My thought is this is due to excess fuel burning off after some sort of ignition failure?? Any advice.
 
Run with a timing light hooked up and see if you are loosing spark when the motor dies.------After the failure and your attempt at restart where is the throttle control positioned for restart ??
 
On restart I have to move the fast idle control lever all the way up and the throttle in neutral. Under normal conditions this will idle the motor at about 3500 rpm. After a cutoff and restart the motor will briefly surge as high a 6500 rpm.
 
First of all idling at 3500 RPM + is a mistake.------You might want to look at all the wiring on the motor.----Does the motor show sign of overheat / melted covering on wiring ?--Sound like there are broken wires in the harness somewhere , may not be easy to find.--------Disconnect kill wire on ignition switch / kill switch and see what happens.
 
3500 is the fast idle condition for start up only, when you lift the control lever and advance the throttle to start. Under load the idle is about 800 rpm. Ignition kill switch was one of my thoughts too.
 
Apparently I'm not explaining this condition correctly. 3500 is not a continuous idling rpm. On start-up after priming the motor I move the fast idle control up to advance the throttle, the engine fires and surges to a max of about 3500 and the fast idle lever is pushed down to idle the motor at normal speed about 900-1000 rpm. Now, after the motor has cutout and I attempt to restart the motor this initial surge is much higher, maybe 6000 rpm. The only reason I mention it is this suggests to me that when the motor cuts out and is restarted there is plenty of fuel present in the system that is burnt causing this surge. Following this logic leads me to suspect an electrical problem instead of a fuel delivery problem. Would you agree?
 
See post #4----Allowing that outboard to wind up to 6000 RPM on restart is a mistake.---------------Many outboard motors do not get a chance to wear out, they are ruined by owners / operators that do not understand how " fine machinery works "----End of my tutorial.
 
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