1996 Johnson 9.9 loses power on full throttle

Need your input!! After running at full throttle (5500 rpm) for about 10 minutes, the engine rpm's drop to about 3200. The loss of power will last up to about 20 minutes, then kick up to normal rpm's for a while, then back down again. Idle is fine and smooth. Problem only persists while running in gear. Could this be a faulty power pack?

Re: 1996 Johnson 9.9 loses power on full throttle

Yep, you are losing one cylinder. Could also be a coil. Alot cheaper.

Re: 1996 Johnson 9.9 loses power on full throttle

Yes, it could be the power pack, but it could also be a faulty spark plug (even cheaper yet). The sensor coil or charge coil could be shorting to ground or perhaps the the powerpack may be double-firing intermitently. You could even have a piece of debris in the carburetor that is intermitently plugging the main jet. The problem has to be isolated to a particular system, then trouble shoot the system to determine what part is at fault. Other-wise, you'll just end up changing every component until you stumble upon the bad one - which is not the most effective or inexpensive way to do it. If the ignition system is at fault, it should be completely tested (per the service manual) when the problem occurs.<br /><br />-John

Re: 1996 Johnson 9.9 loses power on full throttle

i have a 9.9 1996 4 stroke when its cold it will run great for about 2 min then it will bog down and die losing spark on both cyl. let it cool down and it will go for a few seconds and then die again how can i test the cdi on this thing