Revs high in neutral, low in gear

[buccaneer_35]

I'll be taking apart the engine tomorrow, so what I'm really looking for right now is maybe some hints on what to look for. The first problem is that when engine is in neutral I can rev it up high or low with tthe throttle, but when the engine is engaged in gear no matter how much I turn the throttle the engine still revs slowly. Secondly, there is a gas leak, or it is drinking gas. I filled up the tank today, over a gallon, and then it was nearly all gone after 30 minutes of motoring.
This this is a 1990's Mercury 4 horsepower outboard engine with an internal gas tank.

My list of things to do tomorrow: clean the carburetor, check the fuel filter, check the spark plug, check the fuel lines for leaks. Oh, and last week I changed the gear oil and what I think was the first time in many years. This is a new to me engine, this summer.

Thank you for the help.

 

[Scott Danforth]

motors take almost no fuel to rev in neutral, so that does nothing.

motors take a bit of fuel to rev under load. I would start with the carburetor.

 

[fheller]

I'll be taking apart the engine tomorrow, so what I'm really looking for right now is maybe some hints on what to look for. The first problem is that when engine is in neutral I can rev it up high or low with tthe throttle, but when the engine is engaged in gear no matter how much I turn the throttle the engine still revs slowly. Secondly, there is a gas leak, or it is drinking gas. I filled up the tank today, over a gallon, and then it was nearly all gone after 30 minutes of motoring.
This this is a 1990's Mercury 4 horsepower outboard engine with an internal gas tank.

My list of things to do tomorrow: clean the carburetor, check the fuel filter, check the spark plug, check the fuel lines for leaks. Oh, and last week I changed the gear oil and what I think was the first time in many years. This is a new to me engine, this summer.

Thank you for the help.

I know this is an old thread, but I have a problem that is a cousin to this. I have a 2007 HP 5 HP. New to me. Sometimes (often) when it is in neutral, even if the throttle is low, the engine will rev very high and stay there. I would also say it does not rev anywhere near that high in gear (very modest top speed; seems off). Boat is in water now, at mooring, so repairs difficult, must be done from above or from dinghy unless need to remove (challenging). What can I try first to try to fix/improve this?

 

[jbcurt00]

Closed
@fheller start a topic about your motor and ask questions there.

6yrs later, it's best left for research instead of posting to it, esp given its a completely different engine