Engine runs, but not with load

[thunked]

Hello, I have a 1991 Mercruiser 4.6L. It's in a Bayliner, and this boat has been great. I haven't had any issues with it until now.

When I run the boat out of the water, it idles nice, will increase RPMs just fine, and I can put it in gear. Once I drop the boat in the water, when I engage the prop it stalls immediately.

Does this point to an obvious issue? I took off my carb a while ago, and did not replace the gaskets but they were pretty bad. I plan on replacing the carb gaskets this winter and am hoping that addresses the issue. Could that resonably be the cause?

Also, when I run the boat on land it appears that the water coming out from not the bottom - but the prop shaft area is sort of dark, it's not black, but definitely has black in it. Is there any way to tell if this is oil? What's the best way to know if I have an issue with the motor head? Do I check for water in the oil?

Thanks!

 

[Gary H NC]

Re: Engine runs, but not with load

You should never take the carb apart without a rebuild kit and all new gaskets.
The dark exhaust is most likely from an over rich condition from messing with the carb.
And yes it is normal for the water to exit around the transom shield when on the muffs in the driveway..

If you are not experienced in carb rebuilds take it to someone that is.

You sure thats not a 4.3?? Never heard of a 4.6....

 

[thunked]

Re: Engine runs, but not with load

Thanks for the response. Yes, you're right it's 4.3L I always forget, so I figure I'll overestimate you know

 

[Maclin]

Re: Engine runs, but not with load

4.3, 4.4, whatever it takes...

Take the sparkplugs out and look at them, they will tell you if the mix is too rich.

 

[AZSenza]

Re: Engine runs, but not with load

When it wont take a load, its often caused by a weak spark, as cylinder pressure increases, the lack of power at the plug cant jump the gap. Try changing the cap, rotor and plugs, at least take a good close look at them.

 

[Dukeab]

Re: Engine runs, but not with load

There is a kill switch that will allow your boat to run and idle fine but will stall the engine immediately when put into drive if the switch is bad. It's a safety switch

 

[fat fanny]

Re: Engine runs, but not with load

Pay attention to the date on the post's!!!!!!!!!!!