95 mercy 115 2+2 still having problems

flyingscott

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Apr 8, 2014
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Have the carbs been serviced at all? Has a link and sync been done? Those motors are kind of tricky
 

hareymike

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Aug 24, 2016
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It only does this after driving on plane. I didnt think it was carbs because it runs perfectly otherwise. Also, once i rev it up, it smooths out.
 

flyingscott

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I would look at the carbs on it. That motor always fires all 4 plugs the bottom 2 cylinders are controlled by the carbs. They pretty much eliminate the idle circuit except for allowing a miniscule amount of fuel mix thru for lubrication. The bottom 2 carbs also have accelerator pumps on them that can leak fuel through and cause the cylinders to try and fire.
 

hareymike

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Aug 24, 2016
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Hmmm ok. I wonder if when it shuts down then its bleeding by. I also see there are 14psi fuel jets. They are supposed to stay closed below 14psi. They may be bleeding by.
I will check into the pumps. How do i check for leaks.
 

flyingscott

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I would rebuild the carbs completely with the factory kits. It could also be a bad needle and seat. What do you mean by 14 psi fuel jets? Mechanical fuel pumps usually run around 6 PSI. Also for that motor a factory manual is a must and make sure you get the factory kits that have the replacement pumps.
 

flyingscott

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Those are check valves opened by the accelerator pump when it operates. I am going to stick with the carbs as a starting point and change filters as you go
 
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