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Mercury outboard not holding its prime

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bassmaster1234

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"I have a 1981 7.5hp mercury,

"I have a 1981 7.5hp mercury, but every time I need to start it I need to prime it everytime. Anybody have any ideas why?"
 
"Your gasoline that is in the

"Your gasoline that is in the carburetor evaporates, it is one of the laws of nature.That is why your motor has a handy primer/manual pump on the hose."
 
Probably a leaky check valve i

Probably a leaky check valve in the primer bulb. Allows fuel to run back to the tank. Replace the bulb.
 
My fuel line connectors are pl

My fuel line connectors are plastic could this be a problem? Also my connectors are the bayonet type. But my fuel line is only a month old and it is the one they sell at academy.
 
Are you sure you don't hav

Are you sure you don't have an engine problem rather than a fuel delivery problem? Do you have to prime the engine even after its warmed up or when its been turned off for just a short time?
 
"I am talking about everytime

"I am talking about everytime I have to start my motor I have to prime it first. Once it is started it runs fine. My fuel line is only about a month old. My connectors are the push in and turn right to lock in place, but it is the fuel line they sell at academy. So I am guessing I need to purchase the metal connectors?"
 
If you answer the question of

If you answer the question of the time frame between starts them some of the friendly knowledgeable folks can give you an answer / help. So is it 10 minutes or two days between starts???
 
"Robert -- what we need to kno

"Robert -- what we need to know is when you have this problem how long has the engine been turned off. In other words when you get to your boat, you obviously need to prime it. You go out fishing and sit for 10 minutes in one spot. Do you need to prime it again after a 10 minute sit? If you do, fuel is either draining from the carbs or its draining back to the tank. After a 10 minute sit, there should be enough fuel in the carbs to start it even if the fuel in the line drains back. It also doesn't matter if your fuel line is brand new. Brand new things can be defective. Try positioning the fuel line so the primter bulb is vertical rather than horizontal. And above all, make sure your starting procedure is correct (proper use of choke and throttle)."
 
I can run to a spot an fish it

I can run to a spot an fish it for about a half an hour then I have to prime it before I start the motor.
 
How many squeezes on the bulb

How many squeezes on the bulb does it take to get the engine primed again and does the primer bulb ever get really firm?
 
It takes about 5 to 10 pumps t

It takes about 5 to 10 pumps to get it started again. But I am going today an buy a new bulb and metal fittings. I hope this solves my problem.
 
I think you are on the right t

I think you are on the right track. If it takes that many pumps to reprime after 1/2 hour the fuel is draining back through the bulb. I doubt your fittings are the problem though. I'm still bothered by the fact that there should be enough fuel in the carbs to start the engine. It may stall until the line is full again but it should not pose an initial starting problem.
 
Once the motor is running it w

Once the motor is running it will run until I turn it off or run out of gas in the gas tank.
 
"If it isn't the primer bu

"If it isn't the primer bulb, sounds like you have an air leak somewhere between the tank and the fuel pump which is letting you lose the prime. If your new fittings and bulb don't help, look at the lines, and clamps to the fuel pump. A bad fuel pump could also cause the problem."
 
To lose fuel to the point wher

To lose fuel to the point where it takes 10 squeezes to reprime indicates to me that the primer bulb is bad. Air leaks between it and the engine will not allow drain back as the check valves in the bulb prevent that. A bad fuel pump would also cause wide open throttle running problems.
 
I don't have the fianance

I don't have the fianance to but it in the shop. But I pulled the bulb off yesterday to replace it with a new one and found out that the gas was dripping through the check valve. So I believe that I may have found my problem. I also with the motor running I sprayed carb cleaner around all the gaskets and the only place where it blogged my motor down was around the fuel pump area and fuel pump gaskets and diaphram. Thanks for the help guys.
 
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