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motor cuts off on top end.

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lpw

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I have 1984 Johnson J25RCRD 25hp ,Ive claeaned fuel line in tank,replaced bulb and all gas line from tank and inside cover.Ive also rebuilt and cleaned the carb with carb clener ad compressed air,set the float and installed new fuel filter. the air vent on tank is clean and open with fresh fuel . my problem on top speed after one or two mintues it cuts off as if I had pushed the cut off button, I hve also changed water pump and it is running cool. would appreciate an suggestons...thanks.
 
Ive tried that same problem also it has good compression and runs great at idle with no bogging down when giveing gas only dies at full throttle. I have adjusted the carb
at idle and appears all the gas lines are holding very good I started it today after sitting for two day and a very cool night it kicked with just a touch of the start button with
no primeing. one other thing I have installed a starter on it.
 
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Try pumping the primer bulb when it acts up. Also squirt some premix fuel in the carb throat when it acts up.
 
tried both but it doesn't help pulled bowl when it happens and it has plenty of fuel. might add when it shuts down it will also start back up with no problem.
 
I found my problem today, Throttle Control Rod had slipped which caused the carb to open past full throttle and shut the engine down after about an hour of adjusting and readjusting runs great now.
thanks every one.
 
I think that I am having a similar problem but mine cuts off after just about 15-20 seconds of advancing to full throttle. Did you just incrementally back off the adjustment on the motor until it would run?

lpw said:
I found my problem today, Throttle Control Rod had slipped which caused the carb to open past full throttle and shut the engine down after about an hour of adjusting and readjusting runs great now.
thanks every one.
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To get the top end at 4800 rpm I reset timeing with a timeing light adjusted stop scew to 1/2 inch out side thread showing then adjusted the carb. found that on these motors your prop sure made a difference. When I bought the motor it had a 9 1/2 inch 12 degree prop on it but going back to stock prop of 9 1/2 inch by 7 made a huge difference of setting timeing and carb which caused the motor to run 100 percent better.. purchase a manual before you do any type of work on it because if yours has points every thing is different if I can help you futher you may call and I will be glad to walk you thru this.
 
lpw said:
To get the top end at 4800 rpm I reset timeing with a timeing light adjusted stop scew to 1/2 inch out side thread showing then adjusted the carb. found that on these motors your prop sure made a difference. When I bought the motor it had a 9 1/2 inch 12 degree prop on it but going back to stock prop of 9 1/2 inch by 7 made a huge difference of setting timeing and carb which caused the motor to run 100 percent better.. purchase a manual before you do any type of work on it because if yours has points every thing is different if I can help you futher you may call and I will be glad to walk you thru this.
Click to expand...

Thank you very much! I will take a look at the timing when I get it out of the water. Appreciate the advice
 
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