Loss of WOT Johnson 9.9

P

pontoon chief

Petty Officer 2nd Class
Joined
Aug 9, 2004
Messages
116
Have what I believe is an 1987 Johnson 9.9 that runs great in the test can,but when running on the boat the motor acts up.It runs great at low rpm,however when you open it up the motor cuts out at the top end.Using a timing light I found the motor still fires at the top end when it dies out,however the motor dies while the spark continues until it stops.<br />When it cuts out at the top end is appears to starve for fuel,however if I return the throttle to the idle position when it dies ,it will catch and continue running.I cleaned the carb several time and set the float correctly,new fuel can and hose with new fuel.<br />Any idea's...........
 
M

MCM

Lieutenant Junior Grade
Joined
Jun 1, 2005
Messages
1,201
Re: Loss of WOT Johnson 9.9

Did you make sure all jets and passages were clean and free of obstructions? a clean carb is not the same as a rebuilt carb, using old gaskets is like asking for air/vacuum leaks.
 
P

pontoon chief

Petty Officer 2nd Class
Joined
Aug 9, 2004
Messages
116
Re: Loss of WOT Johnson 9.9

Yes,all passages are open.Both air and fluid forced thru all passages.
 
A

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: Loss of WOT Johnson 9.9

did ya let em' soak in carb cleaner first? Like MCM was leaning towards, your main jet is probably partially obstructed.<br /><br />For a check though, pump the primer bulb when it wants to die at WOT. If this saves the engine from falling on its face, then it is time to rebuild the fuel pump.
 
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