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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14579
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 2002 40 hp 3 cylinder 2 stroke mercury outboard engine.

Customer Question

I have a 2002 40 hp 3 cylinder 2 stroke mercury outboard engine. It runs fine when first put in the water. run it about 2 miles down river or so. Stop and shut it off for an hour or so, start it back up, running about 3000 rpm's and in a few minutes the power drops off so it is only running at about 2300 rpm's. You can push the throttle forward all the way, and still stays at 2300 rpm's. the all of a sudden it takes off and is running fine.
Any suggestions ?
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with?
Where you have to start is by duplicating the problem first, and then while out on the water checking spark with either a timing light or an adjustable gap spark tester. That will tell you if it's an ignition problem. If it's not an ignition problem it's likely a sticky float in one of the carbs. Is that something you think you can do?
Customer: replied 1 year ago.
I'll try that. thanks
Customer: replied 1 year ago.
I've had the carbs rebuilt twice in the last 5 years. It sounds like it might be an ignition issue.
Expert:  Jason replied 1 year ago.
You are very welcome William and I was glad I could help. Parts like igniton coils often work when cold, fail when hot, and work when colder again. On any engine, the hottest an engine gets is not when it is running, but about 45 minutes after its shut off. What happens is cooling water stops coming in, and the deepest internal heat of the engine starts to radiate out, heating up everything bolted on to it.
Was there anything else I could help you out with on the issue?

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