Slipping into neutral when accelerating with low fuel?

[baltimoron]

I can't seem to find much on this -- maybe this is a stupid question, and maybe not -- but today I had an issue where we were running with fuel as low as it's been at any point since I've owned the boat, and when accelerating the engine would seem to slip out of gear and the engine would just revv. Still could continue at low speeds, however. I stopped and put a few gallons of gas in the tank from a gas can I carry along, and this seems to put an immediate stop to all these symptoms. Boat got on plane fine and continued running fine for the 5 or so miles back to the dock.

Is this some type of mechanical safeguard to prevent the operator from unkowingly running out of fuel?

Thanks!

[seapuppy]

Wow....that's a wild one....no ..as far as I know there is no safety for that.....usually you run out of gas...you stop...you get low....you run until out of gas....to me what you described was the prop slipping on the hub....or maybe you cavitated and lost thrust...

oh yeah...welcome to the zoo....


SP

[baltimoron]

Right...that's what I thought. Was out in a creek I know well, and run out the same way every time in deep water, so we didn't hit anything, etc. We knew the gas was very low, were on plane on the way back, and then all of the sudden engine seemingly slipped into neutral and started racing. Backed off and put it in gear, and it caught no problem. We tried to get back on plane 2 or 3 times. Got close but easing the throttle up to a point near planing resulted in the same symptom. Stopped to put the gas in, and possibly an interesting cooincidence, but after adding the gas, we got up on plane no problem and took off without further issues.

Not sure how to proceed, and was really hoping the gas and the issue were linked though knew it wasn't incredibly likely.

[baltimoron]

And thanks for the reply/welcome!

[seapuppy]

yeah...I'd take your prop off and over to your local prop shop...for about 60 bucks..+/-..they will recondition the prop...reinstall...should be good to go.....



SP

[shrew]

Originally Posted by baltimoron

Stopped to put the gas in, and possibly an interesting cooincidence, but after adding the gas, we got up on plane no problem and took off without further issues.

If this were a spun prop the symtoms would be the same regardless of how much gas was in the tank. Is this a carb or Fuel Injected engine. I wonder if the fuel was so low you started sucking up water and the engine retarded itself with some kind of 'protection mode'. But then again, I suppose the RPM's wouldn' remain high.

[brianbossman1]

I cant think of any reason that a drive would "slip" in to neutral. The drive is mechanically shifted into forward, neutral or reverse right? How would it slip gears?

I’m thinking that when you’re low on gas the pick up tube in your fuel tank is becoming exposed and is causing poor performance. The engine gets fuel lifts the bow in turn uncovering your pick up tube which causes the boat to lose power allowing the bow to drop and then recovering the pick up tube which starts to process over. Could you be interrupting this as a shift in to neutral?

My only other guess would be the prop hub. This is very interesting.......