idles great on muffs, dies after 1 minute in the water

[livethedream]

figured i should start a new thread on this. i just bought a troubled boat with a 2000 5.0L merc EFI with Alpha 1. i gave it a full tune up and redid the seals and gaskets for the outdrive/bell housing.

It now runs great on the ear muffs, but yesterday I backed it into the water for more tests and it stalls after a minute. What would be killing the engine at idle with more water volume in the lake than it gets on the muffs?

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

going thru the manual over and over again, i keep getting drawn to the MAP sensor as it can cause a no-start, or start-stall problem. Should I run the boat back to the launch and start it with that disconnected?

 

[SweetTooth]

Re: idles great on muffs, dies after 1 minute in the water

I have a 2000 5.7L EFI with a similar problem.

Does your audio alarm beep just before it dies?

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

not sure if mine has an alarm, but haven't heard it. if there is one it probably isn't working as there's some lights and guage issues to address still.

does yours run fine on the muffs but trouble in the water too?

 

[a70eliminator]

Re: idles great on muffs, dies after 1 minute in the water

Are you backing down a steep ramp and trying to start it while still on trailer, I'm just thinking maybe the carb bowls are dumping fuel or running out of fuel do to the angle, you mighnt try floating the boat next time, Oh wait you said fuel injected.my bad. But maybe something else trivial like that.

 

[SweetTooth]

Re: idles great on muffs, dies after 1 minute in the water

No. Mine will run fine out of the marina (no wake idle) then up on plane and after I sit in a raft up for an hour or two the boat will idle for about 1 minute, sputters, and dies. It acts as if the fuel is being shut off.

You mentioned 2000 model boat and owners manual. Does yours sputter and then quit?

I'm really baffled with my case.

Best of Luck with yours

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

Are you backing down a steep ramp and trying to start it while still on trailer, I'm just thinking maybe the carb bowls are dumping fuel or running out of fuel do to the angle, you mighnt try floating the boat next time, Oh wait you said fuel injected.my bad. But maybe something else trivial like that.

I have the rear straps released so its floating. Did a full tune up and covered everything obvious (i think) and runs great out of the water.

No. Mine will run fine out of the marina (no wake idle) then up on plane and after I sit in a raft up for an hour or two the boat will idle for about 1 minute, sputters, and dies. It acts as if the fuel is being shut off.

You mentioned 2000 model boat and owners manual. Does yours sputter and then quit?

I'm really baffled with my case.

Best of Luck with yours

I can't get mine off the trailer, never mind past the no wake zone. If it could drive hovering ABOVE the water I think i'd be good to go, but we're probably 50 years away from that technology.

 

[Don S]

Re: idles great on muffs, dies after 1 minute in the water

Sweetooth, this is livethedreams thread not yours. If you have a question, start a new thread. It's almost impossible to hold 2 different conversations in the same thread.
Read this thread, but ask questions in your own thread.

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

Sweetooth, this is livethedreams thread not yours. If you have a question, start a new thread. It's almost impossible to hold 2 different conversations in the same thread.
Read this thread, but ask questions in your own thread.

no worries Don, any thoughts from a wiser grease monkey than I?

What would be killing the engine at idle with more water volume in the lake than it gets on the muffs?

 

[a70eliminator]

Re: idles great on muffs, dies after 1 minute in the water

Livethedream the only thing thats changed is now your exhuast has to push through a wall of water, it's unrestricted running on muffs, let us know the final outcome good thread topic I'm intrigued.

 

[Don S]

Re: idles great on muffs, dies after 1 minute in the water

Nothing is killing the engine with more water volume. Unless you have the exhaust plugged up with an old exhaust shutter blocking off the exhaust.
Have you had the drive off and looked at the exhaust side lately?
Here is a picture of a flapper blocking the exhaust passage in an older drive. Yours could be there or in the drive itself.

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

Livethedream the only thing thats changed is now your exhuast has to push through a wall of water, it's unrestricted running on muffs, let us know the final outcome good thread topic I'm intrigued.

That's all i can figure as well... restricted exhaust flow. I put on a new exhaust bellow and it didn't improve.

Nothing is killing the engine with more water volume. Unless you have the exhaust plugged up with an old exhaust shutter blocking off the exhaust.
Have you had the drive off and looked at the exhaust side lately?
Here is a picture of a flapper blocking the exhaust passage in an older drive. Yours could be there or in the drive itself.

Yes, I just had the drive off to redo the gaskets and seals, and replaced the exhaust bellow. There's no flapper there on mine.

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

I believe there's a leak at the steering linkage in the transom that I need to repair, but that shouldn't be affecting the engine. If the leak is actually somewhere else on the transom would that be cutting the engine?

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

I'm sucking it up and hired a mechanic to come in the morning to fix this. Any last thoughts to point him in the right direction and hopefully save me some cash?

 

[Don S]

Re: idles great on muffs, dies after 1 minute in the water

Any last thoughts to point him in the right direction and hopefully save me some cash?

Yea, get out of his way and let him do his job without standing over him and watching and questioning every move he makes.

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

LOL, thats easy. I know the feeling when working on motorcycles.

 

[livethedream]

Re: idles great on muffs, dies after 1 minute in the water

Well the mechanic confirmed my worst nightmare. The map sensor is shutting it down and is either faulty or reacting to the knock in the motor that he believes is a connecting rod or valve lifter, or the low compression in cylinder 5 (120 vs. 150), plus the transom is leaking at the steering arm. He said to pull the engine and rebuild it and repair the transom would be $8,000 at minimum. Gulp. I'm going to go get drunk now. Thanks for the help here guys.