4.3 Mercruiser I/O not wanting to plane and short on power.

[86metro]

I just recently purchased a 97 Celebrity 180 Bowrider and am new to boating. The boat has a 4.3 v6 Mercruiser LX engine. When out on the water it has no power when accelerating. It just sounds like it doesnt have any power. Its not missing while its doing this, it just simply sounds like it doesnt have the power. It VERY slowly accelerates and eventually will plane and seems to run fine after that but its only running 4,000 RPM at full throttle with only about 250lbs of weight inside.Browsing all over the internet I found that this motor should peak between 4,400 and 4,800 RPM's. It has new spark plug wires and I checked the plugs themselves and they look farely new. Also removed and rebuilt the carburetor which after getting inside of it looked as if it didnt need it at all. Everything was clean and working properly.

What else could be the cause of this?

 

[45Auto]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

Start with the basics. Do a compression test and check the timing. Do a full tune-up including distributor cap and rotor.

There is no way you can tell if a carb has a clogged internal passage by looking at it.

For some reason I wouldn't be comfortable trusting a carb rebuild and set up to someone who didn't understand engine fundamentals enough to do these basics.

 

[smarks]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

Check the accelerator pump for good operation. Disconnect throttle linkage and look down the barrle of carb to see if it's squirting gas while operating throttle. It may need to be adjusted after your rebuild.
Steve

 

[sethjon]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

You looked at the plugs but did you regap them? Check the fuel filter and is it elec ignition? If not, check the points.

 

[Bliner175]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

I'm having the same issue with my 3.0 and it's a brand new engine. Little power and very slowly getting on plane, then all seems fine.

I'd be interested to know what you find out!

 

[dirtyoldman]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

I just recently purchased a 97 Celebrity 180 Bowrider and am new to boating. The boat has a 4.3 v6 Mercruiser LX engine. When out on the water it has no power when accelerating. It just sounds like it doesnt have any power. Its not missing while its doing this, it just simply sounds like it doesnt have the power. It VERY slowly accelerates and eventually will plane and seems to run fine after that but its only running 4,000 RPM at full throttle with only about 250lbs of weight inside.Browsing all over the internet I found that this motor should peak between 4,400 and 4,800 RPM's. It has new spark plug wires and I checked the plugs themselves and they look farely new. Also removed and rebuilt the carburetor which after getting inside of it looked as if it didnt need it at all. Everything was clean and working properly.

What else could be the cause of this?

You've got some good advice here. It needs a tune up anyway, so start there.

1) The accelerator pump in the carb only affects a bog or loss of power under acceleration. It will not affect power output of the engine.

2) Did you set the float level when you were inside the carb? You could have a fuel problem that is either a delivery issue or an internal problem.

3) I think it's unlikely here because that's kind of a big engine on a small boat, but you could have the wrong prop.

4) You could have waterlogged foam under the floor. Has your boat been parked bow down lately? You could also just have way too much stuff in there.

 

[kpiazzisi]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

I am having the exact same problem you are describing. Can you tell me what the solution ended up being?

 

[180shabah]

Re: 4.3 Mercruiser I/O not wanting to plane and short on power.

86 - after all of the tune up and maint items above, let us know what the gear ratio is in your drive and what prop you have on it.

kpiazzisi - start a new thread, while you may have the same symptoms, we need to address your actual problem seperately.