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mercruiser5,7 problems

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DutchThijs

New member
We have a mercr 5,7 thunderbolt v ignition with carb.It starts poorly(only with full throttle) and the rpm's going up and down.When it reaches around 2000 rpm it suddenly goes up to about 3000 rpm and loses power and wont go higher.
The carb is checked,the distributor is replaced the spark plugs are replaced,the fuel filter is replaced and also the oil filter has been replaced.When we changed the oil we noticed there was a lot of gasoline in the oil.And then i mean a real lot!Could this be a fuel pump problem?Whe the boat is running neutral it has no problem to increase rpm and it will go to 5000/6000.
What can be wrong?
 
rebuild the carb. Post how it runs after. Pay attention to the float cause it's ether hanging up or its full off gas and needs to be replaced.

I don't have to tell you to change the oil and filter again do I ? do it now today right away. Take the key and put it away don't start it play the radio or anything.
 
the carb is allready rebuild, after this the problems only got worse, before, the problems were there allready, but i had normal power at full throttle, i let it rebuild, and the float is replaced because it seemed to be worn out, that was (we thought) the reason for the raising oil level......
I think the person who sold it to me knew about the problems, but tried to hide it by adjusting the carb in a way it (ran to rich) starts better en ran better because it got the max of fuel possible.

Is this possible?
 
it will go up the return clear or yellow hose connected to the carb. Yours have fuel in it ?

Who rebuilt the carb bring it back to him and tell him whats happening. Some carbs just can't be rebuilt.

What psi is the pump giving you.
 
the fuel pump pressure was 10 psi, that is a good vallue.... so that is not the problem.....
can anyone tell me how to find out the carb is pourly rebuilt? how can i see this?
 
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