Kind of a wired problem with a 120 merc

[rpatton]

Hy guys I have kinda a wired problem with my father in laws 1986 merc 120 , it runs great on nice smooth water starts good at wot and idle but when you get into rough water like in a inlet or choppy water it acts like it is running out of fuel at wot , but if we back the throttle off even to 3/4 it runs good until we go to wot and it does it again but only in rougher water and not all the time. We replace the filter at the beginning of the season so I assume it is good. Any ideas?

 

[series60]

Re: Kind of a wired problem with a 120 merc

Hy guys I have kinda a wired problem with my father in laws 1986 merc 120 , it runs great on nice smooth water starts good at wot and idle but when you get into rough water like in a inlet or choppy water it acts like it is running out of fuel at wot , but if we back the throttle off even to 3/4 it runs good until we go to wot and it does it again but only in rougher water and not all the time. We replace the filter at the beginning of the season so I assume it is good. Any ideas?

What makes you assume the filter is good? What if there was crud in the tank and has now plugged the filter. Is there a water separator filter on the engine and was it replaced? Can you see inside the fuel tank for crud? Are the rubber fuel lines in good shape? Fuel lines deteriorate from the inside so it may need some further investigation. Is there something partially blocking the fuel pickup inside the tank.

I mention looking inside the tank because of my personal experience with the resto listed in my sig. I found a 24" piece of black tape floating around inside just waiting to ruin my day!

The carb may need rebuild. Float may be set incorrectly.

starts good at wot

Please don't tell me you start the engine at WOT!

 

[rpatton]

Re: Kind of a wired problem with a 120 merc

What makes you assume the filter is good? What if there was crud in the tank and has now plugged the filter. Is there a water separator filter on the engine and was it replaced? Can you see inside the fuel tank for crud? Are the rubber fuel lines in good shape? Fuel lines deteriorate from the inside so it may need some further investigation. Is there something partially blocking the fuel pickup inside the tank.

I mention looking inside the tank because of my personal experience with the resto listed in my sig. I found a 24" piece of black tape floating around inside just waiting to ruin my day!

The carb may need rebuild. Float may be set incorrectly.



Please don't tell me you start the engine at WOT!

No I mis wrote I do or ever will start at wot!! I plan on changing the filter anyway and it does have a water separator on it . I cannot see into the tank because it is built into the hull which was real stupid if you ask me. I really do not think it is the filter though because it only does it when in rough water not all the time , that being said there could be something in the tank but Norway to tell

 

[series60]

Re: Kind of a wired problem with a 120 merc

You can connect a separate fuel tank like an outboard tank to see if that is where the problem lies.

 

[rpatton]

Re: Kind of a wired problem with a 120 merc

You can connect a separate fuel tank like an outboard tank to see if that is where the problem lies.

That's kinda what I am thinking I was just asking to see if there was any other possibilities