48 Johnson spl '96 bogs down at full throttle

M

myturnow

Recruit
Joined
Mar 28, 2010
Messages
1
Motor bogs down when running full throttle and only allows me to go about 7 mph and will not pick up speed again until motor is shut down and cooled off. I have changed fuel tank, prime bulb and fuel lines to motor. The carb and fuel pump have been replaced and the problem still exists. Is there and other suggestions to which this might be? Any help would be greatly appreciated.
Thanks, myturnow
 
jtexas

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: 48 Johnson spl '96 bogs down at full throttle

You mean it runs fine until it heats up? Cold start, warm start, acceleration all ok?

What's the compression?

Test your overtemp horn, need to make sure the motor's not overheating.

You may have a heat-related ignition failure...
Inspect the ignition coils, look for cracks, melting epoxy.
When it starts acting up, do a spark test, use an inline tester with the gap set at 7/16", look for a good strong spark. If you find no spark on one cyl, swap the coil with the other cylinder, just to be sure. Problem follows the coil, replace it.
 
fireman57

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
Re: 48 Johnson spl '96 bogs down at full throttle

make sure your tank is vented.
 
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