50hp Johnson stalls at trolling speed. Need Help

[USAmike]

1989 Johnson 50hp/Tracker 17' deep V. Runs great at all speeds except at the slowest "in gear" speed, where I want to be for trolling. Been doing this for the the 3 years Ive owned it. It will run a little rough for a few minutes and the stall. I have to bump the throttle up a little to avoid stalling, but then I am trolling too fast.. Gas is good, new plugs, low hours on engine.
What steps should I take to solve this problem? Thanks, Mike

 

[Joe Reeves]

Re: 50hp Johnson stalls at trolling speed. Need Help

First off, that engine is not designed for trolling.

However, the compression should be 100+ psi and even on all cylinders. Is it?

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame, a real SNAP! Does it?

Spark plugs should be Champion QL77JC4 plugs. They can be gapped at either .030 or .040 . Whichever gap you're using, try the other gap setting.

If the three areas above are as they should be, the only other area would be the carburetion. If those carburetors havent been cleaned and rebuilt in the past three years or so and have been sitting for various periods from time to time, they would be fouled somewhat.

Also, perhaps you simply have the idle set too low. On a flushette, the idle should be 1000 rpm for a 20" shaft engine which I believe your engine is. In the water, the idle will drop to its normal rpm.

What exactly is your present idle rpm?

 

[tashasdaddy]

Re: 50hp Johnson stalls at trolling speed. Need Help

as Joe said. also you may need a trolling plate, or troll in reverse.

 

[USAmike]

Re: 50hp Johnson stalls at trolling speed. Need Help

I will check the Idle when I get done with the Seafoam decarb I am doing as we speak. Carb prob. never cleaned. The decarb 1 galon gas to 1 seafoam can is resuting in what looks like diluted lithium grease. Is this what I should expect? Thanks for the reply, often I don't get any responce on iBoats. I generally research the question here before posting. Thanks, Mike

 

[tashasdaddy]

Re: 50hp Johnson stalls at trolling speed. Need Help

"The decarb 1 galon gas to 1 seafoam can is resuting in what looks like diluted lithium grease. Is this what I should expect?"

i don't understand the ???. you need to clean and rebuild the carbs. See the TOP SECRET FILE. the example is your carbs. then do a link n sinc. adjust your idle speed in the water with the motor in gears. it just may not idle as slow as you want. many fisherman up north do what is called back trolling, in order to get there speed down. very common up there. http://forums.iboats.com/showthread.php?t=299680