2000 50HP Cold Start Problem

[KINGGABBO]

I just acquired a 2000 50HP Yamaha. It runs pretty good except for a cold start. When I start it cold, the engine revs to about 2000 RPMs for 30 secs to a minute and then drops down to 600 RPMs or so and then dies. If I give it a little throttle to keep the RPMs around 1200 for a minute or so and then return the throttle to idle position, it will stay running.

On warm starts, the engine revs to about 1200 for a few seconds and then back to idle speed fine and it will stay running. Is this normal with the prime start system?

Any ideas on this? The carbs were cleaned recently but there may have still been some old fuel left in the gas tank. Is the prime start system working correctly? Thanks for the help.

[boats.net]

Check that idle rpm's are set at 800 rpm's in neutral.

[KINGGABBO]

Thanks. I did that out of the water on muffs. Would I need to set it to 800 RPMs in the water?

[boats.net]

It is better to check when in water.

[KINGGABBO]

OK I will set the idle on the water tonight.

[KINGGABBO]

Finally got to try it on the water again last night. It idled fine at about 750-800 RPMs once I got it started. It did the same thing on a cold start again though. Engine revs to about 1200-1400 RPM and then goes down but the engine dies. Any thoughts?

[boats.net]

Check the pilot screw adjustment on carbs should be about 1 5/8 turns out, turn them out another 1/8 turn to see if helps.

[KINGGABBO]

Well haven't had a change to adjust the pilot screws yet because the motor has started running worse. Now it will not idle without coughing, sneezing, and sputtering. Is this possibly a running lean problem? Is there an idle air jet on the carbs that I could turn?

[boats.net]

Then need to remove and cleaned carbs, low speed circuit is plugged up.

[99yam40]

pull the carbs and clean again, do a link and sync like the manual says, but make sure you get rid of the old fuel first and clean out the fuel lines and install a water/ fuel seperator to keep junk out of the carbs.
The prime start gives extra fuel to the motor during cold starts and the CDI unit advances the timing at start up which increases the RPM for a little while to warm up the motor. but if the carbs and dirty it will die when the timing goes back to normal

[KINGGABBO]

Thanks for the help guys. I am going to pull the carbs and clean them this weekend. Also, the fuel tank and hoses. Another thing I forgot to mention is the last couple of times I've run it, it seems to be revving way too high when I start it before it dies. Like upwards of 3000RPM. I would assume it's running lean due to clogged up carb??? And that is causing the surge?