Engine performance problems at altitude...

FishNotWork

Seaman Apprentice
Joined
Mar 17, 2012
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I live in Denver, CO (approx 5300 feet a.s.l) - I have a 16ft Smokercraft with a 40hp 4stroke EFI engine (2006 I believe) - and it runs great at local mile high lakes. Recently we travelled to Dillon, CO to boat on a local lake up there - Dillon is much higher at about 9000 ft above sea level.

When I first put the boat in and started motoring around I noticed that the motor was really, really sluggish - at full throttle it almost stalled. It felt like I had about 1/4 of the regular power available. I had one other adult in the boat and 3 children under 4, 5 and 8yr old with me. A quick storm moved in and we ran to the marina to seek shelter from the waves and wind.

About 1 hour later I took the boat out again and noticed that this time I've regained much of the power - it felt like I had about 80% of the normal power available as compared to about 25% I had earlier.

Is it possible that the EFI computer had adjusted the mixture to a better ratio for the second ride? Why such a difference the second time?

More importantly - should I make some adjustments next time we plan on boating in the high country?!

Thanks,
James
 
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