2006 - 60hp EFI: Loss of power at altitude?

[DarbyDude]

Recently bought a 2006 17' Alumaweld Talon with a 2006 60hp Merc EFI. Had it checked out and serviced at local Merc dealer and everything looked great. Ran it on Columbia River (elevation: 32') and easily got it up to about 25 MPH. Wife loved the boat. Took it to Boise and could only get 11mp (elevation: 3063'). Guardian system? No alarms sounded. Thought maybe the trailer was still attached to the bottom of the boat!

Brought it back to Portland and had it checked out with nothing found and nothing showing on internal computer. Had Smartcraft instrument package put in and took it out on Columbia. Again, everything ran great with RPMs maxed at 5000-5200. So, last week I towed it 700 miles north into deep Canada (lake elevation: 3800') and, surprise, only 11mph again and 3500-3650 RPMs max. Towed back to Portland and, again, everything runs great with 5200 RPMs, 25-27MPH and 4.5 GPH. WTF??? Still caught lots of fish though...

Any ideas? Did not find this in message list. Seems 3800' isn't that high in elevation for a EFI problem. Can get 4000-5000 RPMs with fast idle lever, but not with Control Handle and transmission engaged. Only connection seems to be the elevation. Swapped fuel lines with spare tank and no change. Wife is depressed! What's a guy to do???

 

[CRFan1]

Re: 2006 - 60hp EFI: Loss of power at altitude?

You may need a different prop....you should be between 5500 and 6000 rpm at WOT. That motor is lugging and when you move up in altitude, the resulting loss of HP seems to be making the prop situation much worse. I have the same motor on a 16.5' Alumacraft with a 10.5 x 13 pitch prop and I see 5800 trimmed up and 32 mph with all the gear and 2 people in it.....

 

[DarbyDude]

Re: 2006 - 60hp EFI: Loss of power at altitude?

Thanks,Cadet. I'm taking the boat to a local 'high' lake (3200') in a few minutes to see if it happens again and help verify the problem. It's hard for me to believe this is a standard problem and that folks don't buy the same outboard in Wyoming, Colorado, or any other area that's over 3000' without the need to buy a different prop. So, what happens then if they trailer their boat to a lower altitude? Do they over rev their engine??? I understand altitude changes (O2, pressure, etc.). It just seems that 3000' isn't much altitude for the nearly 40% loss in power. 5%/1000' is 'standard', not 13%/1000'. No loss with my 9hp Merc 4-stroke kicker. That units gave me 8.5 MPH. The 60 hp only gave me 3MPH more... sad.

 

[CRFan1]

Re: 2006 - 60hp EFI: Loss of power at altitude?

Thanks,Cadet. I'm taking the boat to a local 'high' lake (3200') in a few minutes to see if it happens again and help verify the problem. It's hard for me to believe this is a standard problem and that folks don't buy the same outboard in Wyoming, Colorado, or any other area that's over 3000' without the need to buy a different prop. So, what happens then if they trailer their boat to a lower altitude? Do they over rev their engine??? I understand altitude changes (O2, pressure, etc.). It just seems that 3000' isn't much altitude for the nearly 40% loss in power. 5%/1000' is 'standard', not 13%/1000'. No loss with my 9hp Merc 4-stroke kicker. That units gave me 8.5 MPH. The 60 hp only gave me 3MPH more... sad.

Yep, you bring up good points....and that being said, assuming your motor is ok, You still seem pretty over propped. You want to choose a prop that will get you close to 6K on the tach when at your normal altitude. That way, when you do go up high, even though you may lose some RPM do to HP loss, you will still be in the working range of the motor. Again, I am saying this assuming your motor is not having any issues. Do you know what size prop is on the motor now?