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motor not running at full speed

jeffbar's Avatar

Join Date: Oct 2008
Posts: 1

10-13-08, 07:11 PM   #1  
motor not running at full speed

i have a 1968 johnson 20 hp.I had the carb rubuilt and it ran fine for awhile,now at full throttle it runs at about 1/4 speed.It will run at high rpm's when in neutral but when i put in forward it barley runs

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samuari's Avatar

Join Date: Jul 2008
Posts: 541

10-13-08, 08:25 PM   #2  
check your spark plugs if in dought replace them they are cheap.Also for water or other "stuff" in the fuel.

TJ Hornet's Avatar

Join Date: Sep 2006
Posts: 38

10-15-08, 02:25 PM   #3  
I'm no expert but I had a Merc doing something simular. I had a air leak at the fuel tank connection and it couldn't draw enough gas under load with the throttle up. When you have the unit out try pumping the fuel ball to see if it;s hard or it runs better then. Could also be a dirty fuel filter. Good Luck TJ Hornet

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