won't plane??? help

[awwshutup]

We have an '85 Sunbird, 4.3liter, with OMC Cobra outdrive. Boat won't plane. Have replaced carb., points, plugs, distributer cap. Engine seems to be running good when not engaged. When it is engaged motor sounds like it is under a strain. Only maxing out at 3000 RPMs. The prop that is on it is 3 X 14.8 X 17. We just bought this boat...any help would be appreciated.

 

[steelespike]

Re: won't plane??? help

Have you checked the timing?Have you checked the compression?<br /> The carb could be dirty.You might try VERY CAREFULLY squirting gas into the carb to see if it responds.

 

[JB]

Re: won't plane??? help

I/O trouble. Not outboard, not non-repair.<br /><br />Moving to I/O

 

[awwshutup]

Re: won't plane??? help

yes we have checked timing and the compression. Motor is working fine until it is engaged. What do you think about the outdrive? Could the problem be there?

 

[whywhyzed]

Re: won't plane??? help

What size of boat is this with the 4.3?<br /><br />how does the boat sit in the water? There's not 75 gallons of water trapped under the floor somewhere?<br /><br />Suppose it could be outdrive with the wrong ratio in it, but I would think you should still get on plane even if it takes a while....<br /><br />What were the numbers from the compression check?<br /><br />Engines can sound great revving up in neutral when they are actually very sick...<br /><br />What altitude are you at? up in the mountains?

 

[Don S]

Re: won't plane??? help

Here is a chart of many of the possibilities. Time to start eliminating them one by one.<br /><br />

 

[awwshutup]

Re: won't plane??? help

Thanks for the replies. We are gonna check on some of your suggestions today. Will let you know what happened when we get back in.