I broke down today - any ideas?

[slapshot11]

Today I was able to go for a boat ride after work ride. A rare treat. A few minutes into my ride, I heard the motor rev up like the boat was airborn and the prop out of the water. I had hit a few waves but didn't think I left the water. Then on the ride home, I was running WOT when all of a sudden the motor rev'ed up again and everything shut down and stopped. The boat de-accelerated quickly, the alarms went off and the motor shut down. I was dead in the water.
After I was towed in, I was able to re-start the motor while at the dock but I didn't try to put it in gear.
After thinking about it, I heard the motor rev up like this 2 weeks ago when I was out for a ride with my daughter. I thought I spun the prop hub. But the boat ran fine after I slowed down and accelerated again.
Could I be lucky and only have spun the prop hub again or do you think I'll be rebuilding the lower unit.
Help please.
Thanks

[Sagbay32]

Any smoke or burning rubber smell from coupler?

Mike

[slapshot11]

No smells at all. I opened the engine hatch and didn't smell anything unusual or see anything out of place.

[Dr. Dan]

:smash: Stick another prop on and try it...I spun 2 on mine last year in less than 3 weeks...sounded similar...in fact when I was in LG this Spring it did it again...like I had spun one and it turned out to be ok...Buizilla thought it mighta been the Clutch in mine...but its been fine since...

I carrry 2 Props just in case in the boat...with a Block of wood and all the tools. In Lake Winnie I ran pretty hard...and had no issues... so WTF?

Let us know how ya make out... might pay to have the Drive Serviced and checked out if ya haven't since ya got it.

Doc :cool!:

[slapshot11]

Hey Doc,
I hope your right and it's only the hub. I spun one last summer and it scared the sh*t out of me. I'll put the Mirage back on it Saturday and see what happens.
I've had the lower unit pulled and serviced by Performance Marine in LG each spring, sooooooo hopefully it's nothing big.
Hopefully be running again for the fall picnic at LG.
Norm

[slapshot11]

Well here's the deal. It was the battery. My battery was dead from not using the boat in several weeks. It's old. So I jump started the boat to take it out and then again a second time after I docked for about 15 minutes. The mechanics theory is that the combo of a bad battery and 2 jump starts resulted in a voltage surge that automatically shut everything down. After installing a new battery, the boat ran fine with no apparent prop or lower unit problems. The mechanic said that they scared themselves when they took the boat out so I guess it's running OK.
I hope that's all it is.

[realbold]

OK, so what made the engine rev :confused: :confused: :confused:

[slapshot11]

I hear ya. I'm not sure I'm buying it either but I'm hopeful. I'll probably find out when I take it out again on Saturday.

[Pismo]

EFI engines act very oddly with weak questionable batteries. A good new hot battery can make a lot of difference. To anyone who is burning up props, get a solid hub prop.

[margo]

what kind of a carb do you have ...This happened to me pulled the carb took it to the mechanic who rebuilt my engine he took a screw out somewhere inside the center of the carb dumped out what looked like a needle valve put it back in it took about 10 min. to do was fine after that carb is a double feed holly 575... still don,t know what he did Joe

[slapshot11]

Margo, the engine is a 502 with EFI. Put the new battery in and the problem has not gone away. The boat is at Performance Marine right now getting checked out. So, more to come on this mystery soon I hope. I'd like to have it finished by this weekend so I can attend some portion of the LG Donzi Club Fall Picnic.

[realbold]

Remove the nut and it should slide off. Might need to give the hub a whack with a mallet. :smash:

[slapshot11]

I got the boat back from Performance Marine on Friday, ran it Friday afternoon, Saturday morning and Sunday with no problems. Jason's diagnosis was a bad sensor. After scanning the motor with the Mercruiser computer, several error messages related to high engine temp showed up. Odd, because the motor never overheated, the temp gauge stayed right on 160 throughout my whole ordeal, PF's test ride and running at the shop. So apparently, the Engine Coolant ECT Sensor was signaling high temps when in fact there were none. As a result, it would shut the engine down as it's supposed to when temps get too high. End result, the faulty sensor was shutting down the engine when it did need to be shut down. He also replaced the Air Temp Sensor.
Mystery solved, life back to normal.:yes: