Surging problems

[leetbeef9999]

Hey again,<br /><br />OMC Cobra here (5.7 litre, 4 barrel carb, 350 cid). She's in gear at 2000 rpm. The boat is running fine, and then given a little gas, the engine starts surging - the tach jumps, but the speedo does not - the boat goes at the same speed after the surging, there is no increase in speed. Tach and Speedo are working, and there isn't cavitation. Any ideas?

 

[WillyBWright]

Re: Surging problems

The motor is increasing RPMs but you're not going any faster? Spun prop hub or engine coupler. If you have a spare prop, try it. If not, this might be a good time to consider one. If you can smell hot rubber at the back of the motor, then it's probably a spun coupler instead.

 

[beezee28]

Re: Surging problems

willybwright, I have an alomost similar situation on my 3.0L mercruiser but when I look at the prop it looks fine like how it was supposed to be. After pulling the trottle back and then put it into forward gear it ran fine and no problems after that. Any idea what is casuing this jump in rpm. My 1st thought was that the engine was not warm enough as I took the boat out after starting and letting it idel for about 3 minutes at the dock.??