4.3 Merc uneven water distribution/ loss of power

[Platz2001us]

Hey everybody, having an issue and wanted to get your take. I have a 2003 carravelle bowrider with a 4.3 merc. I was headed across the lake today and I noticed a loss of power. I looked back and I had an uneven wake, there was water coming up the stern of the boat. It almost looked the the out drive was trimmed up but I stopped and checked and it was trimmed all the way down. I was thinking fouled plugs. It seemed odd that it would die out like that in the middle of running on a load. I’ll be taking it back out tomorrow to test it. I had people onboard today and did not want to chance it.

 

[Bondo]

and I noticed a loss of power.

Ayuh,....... Welcome Aboard,..... Check the Contents of the fuel filter, for anything but clean fresh gasoline,.....

 

[Platz2001us]

I guess I should have said that I pulled about of quart of water out of the tank by running the fuel pump. Also when this issue happened today, there was a louder humming vibration.

 

[russvanatter]

Couple things come to mind here. One is fuel and the other is ignition. Had three similar issues on 3.7 which lost power.

The first incident turned out to be a cracked negative battery terminal connection. Replaced the battery cable and problem went away.

The next time I had a loss of power, it was accompanied by a growling sound and engine was running but prop and everything else behind the transom was not. Turned out to be the engine coupler failed (after about 10 years and hundreds of hours operating without doing engine alignments.

And finally again after the upper drive bearing overheated and basically ate themselves. This of course was the result of a stubborn stern drive oil leak that I simply didn't want to deal with. Eventually the leak seemed to stop. Well, that was because there wasn't any oil left in it. That was expensive.

Sometimes trial and error is the only way to get through these issues, but never let routine maintenance go by the way side.

 

[Rick Stephens]

If you find water in your fuel, and that fuel has any ethanol in it, then in some ways it is surprising that the engine runs at all. When water and gas with ethanol mix, the water instantly binds to the ethanol and they separate from the gas. Since the ethanol provides around 15 percent of the octane in the gas, what is left is usually too low octane to support proper combustion in your engine.

Couple cures, drain all the fuel and start over - replace fuel filters and rebuild the carb. Water in the carb will always cause build up of contaminants and block ports.

There are some that say you can add ethanol to get your octane back up where it belongs. I've never tried it. Stopped using any ethanol gas in my boat years ago.

Whatever you do, you must get the rest of the water out. It is still combining, degrading and separating your fuel.

 

[Bondo]

I guess I should have said that I pulled about of quart of water out of the tank by running the fuel pump. Also when this issue happened today, there was a louder humming vibration.

Ayuh,..... Then the filter has more water, restrictin' the gas flow,.....

 

[Platz2001us]

Thanks everybody, there is an update. Replaced fuel filter and it half cured the issue. I ran it today and at low RPM, you could feel the engine kicking in in out like it had a dead plug. Now on to this next problem. As I was pulling the boat out, I noticed I had blue/green lower unit oil coming out of what looked like a 3/8 dry rotted hose that goes to the transom. Any ideas on what I should tear apart and check?

 

[Bondo]

I noticed I had blue/green lower unit oil coming out of what looked like a 3/8 dry rotted hose that goes to the transom.

Ayuh,...... That's the hose for the outdrive oil, that goes to the bottle in the motor box,.....