Engine hesitation??

[EricJRW]

Re: Engine hesitation??

Yeah, it's a mystery. Spun prop is always a possibility of course, but it seems unlikely since he's swinging a brand new one.

True. I should have added that when my prop "spun out" the engine over-rev'd in the screaming banshee sense. I'm sure I lost all forward power, but with the engine screaming all I could do is back off the throttle (almost instantly). After the prop spun out, I could get to a certain RPM and keep a constant speed, but as soon as I exceeded the RPM, the prop spun out again.

So yeah, it does not sound like 7lazy77 has a spun prop (but I too chased the ventilation issue for a while before finally figuring out it was spun - via marks as I recall). I will be very curious to see how this problem gets resolved.

Eric

 

[lncoop]

Re: Engine hesitation??

Hey lazy, didn't someone float the altitude theory last year? Was that theory ever adequately addressed?

 

[7lazy77]

Re: Engine hesitation??

Incoop: I can get my rpm's up to where they need to be 4500-5500, but the jar tends to happen near WOT at 5000-5500 rpm's. Being new to boating, I "assumed" I had the altitude corrected by changing the prop to a 11p from a 13p (per my local boat shop). Should I consider a lower pitch?

EricJRW: Your experience sure sounds very similar to what I am running into. My pontoon only has 2 toons. There is a little grim on them, but not much. What is the best way to mark a prop/hub that won't come off in the water? Would still like to try this just so I can be sure this is not my problem.

 

[EricJRW]

Re: Engine hesitation??

If you can see your cotter pin, that can be mark number 1. Make another mark (permanent marker, nail polish, touch-up paint pen, etc.) on the prop that lines up with the cotter pin. If that does not hold up, you could scratch a small line (the prop I was testing was old and very used, so I did not mind marring it, but with a pretty new prop I'd use a non-destructive mark). Also, I'm assuming all props have a cotter pin. Since the hub is splined it, will stay orientated to the shaft. You just need a mark on the prop to see if it moves relative to the hub. And you are right, it's an easy enough test to do to conclusively rule out a spun hub.

PS. I now seem to recall that some props have bendable tabs to lock the nut... If that's the case I suspect a mark (line) on the end of the shaft would suffice.

 

[7lazy77]

Re: Engine hesitation??

Sorry for the delayed response, we have had some pretty bad weather here lately that kept me from getting the toon out. I had a chance yesterday to get it on the water & try the spun prop test by marking the hub & prop with fingernail polish. The problem happened several times yesterday again & after checking the marks when I was done for the day, they were still in line, so this NOT the problem & I can cross this off of my list!

Sooooo, at this point I guess this leaves me with it being either a ventilation problem?? Any suggestions on what to do or how to confirm this???