Surging 50 HP

[Scott Kirkman]

I'm not sure exactly what motor I have, the case is from a 74, but I think the power head is an '86, based on the carbs. If it matters I'm running a jet lower unit. I've cleaned the carbs completely and had it running great at one time. A few weeks back, I hit the wake of another boat at speed and the motor went to about half speed. I think I stuck a float. I took the carbs apart and re-cleaned and checked the float drop, then re-assembled. Now when I give it throttle, it briefly goes to top RPM's, then drops, then goes back up. It will do this for 10-20 seconds, then run normally. If I slow back down to idle or shut it off, it repeats the process. Any thoughts?

 

[hotrod53]

Re: Surging 50 HP

More detail may be required to diagnose the issue, is it bogging or is it losing a cylinder?

Maybe you have a bad coil or electronic pickup and its dropping a cylinder?? Maybe you have a bad switchbox? Does it seem to cut in and out? In my experience with other 2 stroke motors, a coil will drop at higher RPM or higher load. Maybe its as simple as a plug going bad...LOL... it's never that easy...

 

[Scott Kirkman]

Re: Surging 50 HP

I don't think it's dropping a cylinder, it sounds and feels fuel related.

 

[hotrod53]

Re: Surging 50 HP

Lets start with the stupid questions:

Is the fuel vent open on the tank?
Is the fuel filter clogged? (If you have one)
These things have 2 fuel pumps, maybe one is failing?

I am by no means an expert but have done a lot of work on 2 strokes in the past, mostly dirtbikes and mowers.