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Mercury outboard throttle question

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bassmaster1234

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I have a 1981 mercury outboard

I have a 1981 mercury outboard 7.5hp that when I throttle it up there seems to be a flat spot and then it goes into high speed. Anybody have an idea? Another question I have is on the fuel line connection on the motor itself the fitting is missing the needle valve in it. And the question I have would that make the motor hard to start sometimes? But when it starts it runs well. I am just guessing if the needle valve isn't there the gas is flowing back to the gas tank. :fish:
 
"If by "needle valve"

"If by "needle valve" you mean the check valve in the fuel inlet fitting, that shouldn't make the engine hard to start as the check balls in the primer bulb would prevent fuel backflow. What is your cold and hot starting procedure? As for the flat spot, when was the carb and fuel pump last rebuilt? Have you tried carb adjustment? Did you just acquire the engine or if you owned it for a long time -- did the engine just begin acting this way."
 
There has to be a transition f

There has to be a transition from low speed jet operation to highspeed jet operation.It is quite normal for some lag. If it annoys you than open up the lowspeed jet 1/8 turn at a time.The needle/check valve was likely taken out by someone guessing and hoping that somehow the motor would start running better.Those motors also had some problems with the lower crankshaft seal.
 
I purchased this motor last we

I purchased this motor last week. When I purchased the motor the owner told me that the motor was completely rebuilt and a new fuel pump was installed. As for cold and hot starting procedure what do you mean? I also have another question on the throttle setting I noticed the lever above the carb that touches the area just below the flywheel as you throttle up. The area that I am talking about is curved. Does the lever to all the way to the end or is there a certain point it should stop at?
 
"Robert,

The throttle lever

"Robert,

The throttle lever does not travel until it stops. The throttle plates are not supposed to open completly, that is , until they are parallel to the direction of flow. They must be slightly closed at full throttle. It is nesessary for proper fuel flow.

That lever is probably made of plastic, and can easily be broken, so it pays to have at least one spare on hand.

The flat spot you spoke about might be impossible to get rid of. Sparky is on the money there. Another thing you could try, is to change the the throttle pick up. This is the point at which the throttle plate begins to move as the timing advances. If the throttle opens too late or too early it could also cause the problem you have.

Tony"
 
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