Low RPM WOT

[fountain31]

I have been running fine all summer and this past weekend noticed the port engine surging then not being able to go above 3000 RPM. I have a pair of Merc 225 3.0L Carb 1997 that have run beautifully for years. I broke the carbs down and cleaned, checked compression all 115 cold start, yet when I run her at idle I get quite a bit of coughing and what seems to be back pressure on the fuel lines. One of the carb lines split open and another started leaking at the fitting. Replaced the 1/4" fuel lines and filters; does this indicate anything obvious?

Thanks

Ray

 

[Texasmark]

Re: Low RPM WOT

Common fuel source? If not suspect source on malfunctioning engine.

Coughing or Sneezing as some call it usually indicates a lean condition. Not being able to get to adequate rpm's also could point to "too lean" an engine.

Since you did what you did, I'd first manually keep the squeeze bulb firm while the engine is running, both at idle and at high rpm's. If the problem is solved get a new water pump kit.

If not I don't know.

Mark

 

[fountain31]

Re: Low RPM WOT

Thank you Mark, today I'm going to make sure I have spark at all cyl and if I can get the other half to go out after will try the primer bulb while she steers.

 

[fountain31]

Re: Low RPM WOT

I have good spark on all cyl and did find the lowest bleed hose on the starboard side disconnected from the check valve, would this cause the "coughing and sneezing" the engine has been going through?

 

[Texasmark]

Re: Low RPM WOT

Get "Chris1956" to answer that question. I would have to look at the engine to offer my comments......don't remember where the hose is connected and purpose.

Mark