boat will not plane since moving to high altitude

[donzach]

I purchased a 1989 18 ft. sunbird center console with a 1989 88 special Johnson outboard motor. When test driving the boat it ran great, with no problems planing. I have since brought the boat back to Nevada and now I am having problems getting the boat to plane. Could loss of power be due to altitude? How can this be corrected?<br />What other alternatives could help: prop, spark plugs, etc? Thank you.

 

[FlyBoyMark]

Re: boat will not plane since moving to high altitude

What altitude are you at? Yes, if was marginaly powered to begin with....(load has something to do with this also...) You may need to change to a smaller jet and less pitch prop.

 

[JeffK]

Re: boat will not plane since moving to high altitude

If you have increased your altitude from where you purchased and tested the boat...jetting the carbs will be required because of the thinner air. If you have little or no experience with this then you should have an authorized mechanic do this for you.

 

[donzach]

Re: boat will not plane since moving to high altitude

The altitude in Elko is 5500 feet. The test drive had 3 people on board and I now have trouble getting the boat to plane when I am alone in the boat. What does jetting the carb. mean? Thank you for your responses, any help is much appriciated.

 

[FlyBoyMark]

Re: boat will not plane since moving to high altitude

Yep...Need new main jets...see your OMC dealer for proper application and you will need to reprop 1" to 2" less pitch...and of course there will be a loss of speed. Derate your HP by about 25% and thats what your engine will be putting out....88 SPL (or 90 HP..)= 68 HP roughly. MOST IMPORTANT..DO NOT RUN ENGINE AT LOWER ALTITUDES UNLESS YOU CONVERT BACK. THIS EQUALS A BLOWN ENGINE BECAUSE OF EXCESSIVLY LEAN FUEL/AIR MIX!!!!!