2003 runs rough then takes off

[triton2]

I have a 2003 Merc 200 carb. The engine runs fine first thing off the trailer, but as the day goes on it has touble getting up on plane. It revs fine to about 2000 rpm the straightens out about 3500 rpm. Once it decides to go it runs fine. I replaced the pump ball and filter, and cleaned carbs. The airbox is also filling up with fuel.

 

[j_martin]

Re: 2003 runs rough then takes off

I have a 2003 Merc 200 carb. The engine runs fine first thing off the trailer, but as the day goes on it has touble getting up on plane. It revs fine to about 2000 rpm the straightens out about 3500 rpm. Once it decides to go it runs fine. I replaced the pump ball and filter, and cleaned carbs. The airbox is also filling up with fuel.

You have a needle valve failing in one or more carbs. Float adjustment is pretty critical, and can be knocked off if yer a little klutzy putting the bowl on. (ask me how I know)

'nother thing that has bitten me is that you have to use new gaskets any time you take the bowl off. They don't re-seat gracefully, especially the little one in the middle of the bowl, and that leaking will act just like you describe.

hope it helps
john

 

[sschefer]

Re: 2003 runs rough then takes off

What john say's... we've both been there..

 

[triton2]

Re: 2003 runs rough then takes off

Done all that now it will not keep fuel in carbs. Its like it is draining back into tank while fishing. I am on my third pump ball so dont tink that is problem could it be fuel pump.

 

[sschefer]

Re: 2003 runs rough then takes off

Done all that now it will not keep fuel in carbs. Its like it is draining back into tank while fishing. I am on my third pump ball so dont tink that is problem could it be fuel pump.

Most certainly could be a bad check valve in the fuel pump. Order a rebuild kit and rebuild it. Won't hurt to eliminate it from the equation and it's only a 30 minute job.

 

[j_martin]

Re: 2003 runs rough then takes off

Woah wait a minute. There's no way fuel will leak back through the fuel pump unless it is anti-gravity grade and can go upward through the needle valves.

However, if it seems to go down a couple of pumps, it might be fuel leaking from the top carb bowl, through the enricher valve, and behind the second and third carbs. That could explain the bad behavior.

hope it helps
john

 

[sschefer]

Re: 2003 runs rough then takes off

Woah wait a minute. There's no way fuel will leak back through the fuel pump unless it is anti-gravity grade and can go upward through the needle valves.

However, if it seems to go down a couple of pumps, it might be fuel leaking from the top carb bowl, through the enricher valve, and behind the second and third carbs. That could explain the bad behavior.

hope it helps
john

John, I think, he thinks it's draining back into the tank not the engine. Bad fuel pump check valves can do that I think.

 

[j_martin]

Re: 2003 runs rough then takes off

John, I think, he thinks it's draining back into the tank not the engine. Bad fuel pump check valves can do that I think.

Pray tell how the fuel gets out of the carbs back into the fuel line. Antigravity?

 

[sschefer]

Re: 2003 runs rough then takes off

Pray tell how the fuel gets out of the carbs back into the fuel line. Antigravity?

That mariner 100 that I had would do it when the engine was tilted (not trimmed) up full. Turned out that the checkvalves in the fuel pump had sucked through. Not completely but enough to break the seal. Near as I could figure the needles on the float were leaking when it was full tilted. It stopped after I rebuilt the carbs and fuel pump but I did them at the same time so I'm not sure which one it was.

 

[triton2]

Re: 2003 runs rough then takes off

I have got 2.5 inches of vacuum on the pump dont believe that is the problem. Any other ideas?

 

[triton2]

Re: 2003 runs rough then takes off

This motor has a stainless prop could the plastic plugs in the prop cause this problem?