3.0 Mercruiser Hard Starting in High Altitude

[Sonic Blue]

My 2007 3.0 Mercruiser runs great and always starts easily at sea level or less than 1,000 feet. When I get to high altitude at Big Bear 8,000' or in the Sierras 7,000' it will fire and it has fuel, but it is very hard to start. This continues after the engine has run and is warmed up. Starting fluid is no help. It is not flooded. I have advanced the throttle at the stop with a screw driver and that helps. It runs great once it starts. Is there a common fix for hard starting at high altitude?

 

[Fun Times]

Re: 3.0 Mercruiser Hard Starting in High Altitude

My 2007 3.0 Mercruiser runs great and always starts easily at sea level or less than 1,000 feet. When I get to high altitude at Big Bear 8,000' or in the Sierras 7,000' it will fire and it has fuel, but it is very hard to start. This continues after the engine has run and is warmed up. Starting fluid is no help. It is not flooded. I have advanced the throttle at the stop with a screw driver and that helps. It runs great once it starts. Is there a common fix for hard starting at high altitude?

Are you pumping the throttle 2 times and leaving it open around 1/4 throttle while cranking? you might have the "turn key system" but the manual will tell you to still pump it if it is still hard to start. Also there is a chance the throttle screw was not set 100% right from new because it takes a little time in adjusting to get it just right, And you may have helped it a little. What style boat do you have?