2001 150 Johnson has violent jerk any ideas

During the summer my 2001 Johnson 150 V6 with spark pulgs developed a problem and it's gotten worse. Now, when at RPM over 1500 the eng will have a violent jerk/knock that shakes the entire boat. The higher the RPM, the harder the jerk. Eng idles fine, shifts into forward and reverse fine. Runs fine except for this problem. There is no backfire heard when it happens, just a loud mechanical jerk sound. Earlier this summer it may only do it once or twice a trip, but now it's getting worse. It will do this multiple times in a row sometimes, or just one right after another, then might run fine for a few minutes. There is no vibration in the boat until eng does this jerk. Any ideas?<br /><br />Fred

Re: 2001 150 Johnson has violent jerk any ideas

Does it do it in reverse too?? I'm thinking maybe your foreward shift dogs are slipping.

Re: 2001 150 Johnson has violent jerk any ideas

yup, sounds like the dogs are slipping... my other motor does this... im gonna be fixing that as soon as im done with my 90hp.