Bogs down at full throttle

[Patviking]

Hi, I have a 1971 9.8 hp mercury, the problem is it will run fine up to about half throttle,, anything more and it kind of just bogs down, doesnt lose speed but wont go faster no matter how much more throttle. Some other symptoms are it pops at low idle and sometimes dies, have to choke it to get it goin again. sometimes the primer bulb goes flat and the engine dies. The spark seems to be good. Every once in a while it will kick in and i can go full throttle but when i slow down and then try more throttle it just bogs again.. What is most likely to cause this? Thanks in advance.

 

[craigrhoades]

Re: Bogs down at full throttle

I've been going through a similar problem. I would say if the pump ball is literally going flat that's probably a bad pump ball.

 

[pugo]

Re: Bogs down at full throttle

if your ball is going flat, sounds like your fuel tank aint venting..!

 

[j_martin]

Re: Bogs down at full throttle

if your ball is going flat, sounds like your fuel tank aint venting..!

or the pickup screen is plugged (oil bottle foil seal)

or the fuel line from the tank to the ball is shedding it's inner tube.

or the ball itself is kaput.

hope it helps
John

 

[Patviking]

Re: Bogs down at full throttle

The pump ball only goes flat once in a while... It still bogs down even whe the ball is full.. Is there anything else that would cause it to bog down past half throttle?

 

[j_martin]

Re: Bogs down at full throttle

The pump ball only goes flat once in a while... It still bogs down even whe the ball is full.. Is there anything else that would cause it to bog down past half throttle?

When the ball goes flat, it's waaaayyyy over the hill. It's a clue that you have a problem where I outlined in my last post.

But what do I know?

 

[Patviking]

Re: Bogs down at full throttle

k thanks j, i will check what u said

 

[RiverKnight]

Re: Bogs down at full throttle

Hi, I have a 1971 9.8 hp mercury, the problem is it will run fine up to about half throttle,, anything more and it kind of just bogs down, doesnt lose speed but wont go faster no matter how much more throttle. Some other symptoms are it pops at low idle and sometimes dies, have to choke it to get it goin again. sometimes the primer bulb goes flat and the engine dies. The spark seems to be good. Every once in a while it will kick in and i can go full throttle but when i slow down and then try more throttle it just bogs again.. What is most likely to cause this? Thanks in advance.

Try this, when it starts to bog hit the choke and see what happens, if it takes the gas and goes then you got a carb. problem and you gonna need to rebuild the carb. if no affect then its gonna be one of these ....fuel line , tank, or the fuel pump...

 

[Patviking]

Re: Bogs down at full throttle

Will try that. thanks riverknight

 

[Patviking]

Re: Bogs down at full throttle

Just an update on my motor. Turns out it was the points that needed cleaning and regaping, Runs at full throttle now perfectly. It still stalls out when im trying to troll very very slow speed.. have to choke once to get it restarted