jerking above half throttle

[hagers11]

Hi everyone and thanks in advance for your time.

I have a 1980 Cobia Charger w/ an 85hp Chrysler outboard. I am not sure what year model the motor is as its inaccessible at the moment and I am not sure where to look for the id plate anyways. I have read quite a few threads but none of them quite hit the nail on the head of the symptoms that I am having. Above half to three quarter throttle the motor jerks so hard that I am afraid its going to rip the transom off. I have had conflicting opinions from not so credible sources telling me its a backfire and the other telling me it is jumping out of gear. I have a lot of experience troubleshooting driveability w/ automobiles but I am clueless to this.

The motor runs great, fires right up when it is manually choked (choke actuator doesn't work something else to take care of) slips in and out of forward and reverse without a problem. No symptoms until the throttle gets pushed a certain distance then the entire motor jerks w/ a loud pop almost like it hit something underwater. At this time the boat is cruising at about 25 to 30 mph. There is no consistency w/ the jerking only that it occurs in 3 to 5 second intervals and when you let off the throttle a little it goes away. Any suggestions however far fetched would be greatly appreciated.

 

[roscoe]

Re: jerking above half throttle

Most likely worn clutchdog, which is a gear with only a couple teeth on it. It is used to shift into and out of gear. When the corners or edges of the teeth get worn, they slip out of gear when put under a load; such as increasing to 3/4 throttle.

There is a chance that it can be removed and installed backwards, or you can have the surface recut, or replace the clutchdog.

$175 for the part plus labor to replace it, or perhaps getting it re-faced for $40 plus the labor. Or buy a factory or Clymer service manual and do it all yourself.

 

[budlightman82]

Re: jerking above half throttle

Hello I am new on here and have learned alot fom people on here about several things

I had to reply to you post because I own a 1975 75 hp chrysler and I was having the same problems and I found it to be a loose ignition wire on the key switch that every time i hit a small wave or what not it would loose connection and and motor would shut down and refire very fast as if you were flipping a light switch on and off very fast as the wire was bumped around. I hope this helps