MerCruiser 3.0 Idling problem...and no Power

[scottinvabch]

I have a 2003 Bayliner Capri 175 w/3.0 MerCruiser. The engine just started running really rough this weekend. Ran great two weeks ago...no problems! I have cleaned the carb and added fuel system cleaner to the tank. I tried testing the plugs by pulling the wires off with the engine running and i got some strange results...when i pull sparkplugs wires 1 and 2 i notice a definite difference in the way the engine is running...its starts running alot worse then what it already is. When i pull the wires from either 3 or 4 i notice no difference in how the engine is running. I have since replaced the plugs this afternoon but am still getting the same results. Any ideas!!??

 

[Bt Doctur]

Re: MerCruiser 3.0 Idling problem...and no Power

check the riser. probably leaked a bit of water and the valves may be stuck or the pushrods broken.. a compression test will show for sure.

 

[Don S]

Re: MerCruiser 3.0 Idling problem...and no Power

Do a compression test. Had one not long ago where the guy said it ran fine, just wouldn't get up to speed.<br />Must have thought I wouldn't notice it ran rough when I test ran it, and the compression was zero in one cylinder. probably due to the intake valve head breaking off and imbedding in the top of the piston.

 

[RandyJ]

Re: MerCruiser 3.0 Idling problem...and no Power

crossed plug wires (would probably backfire) or plug wires not plugged into distributor cap??? Bad plug wires (doubtful)...

 

[chrisg]

Re: MerCruiser 3.0 Idling problem...and no Power

I have a 1950 classic, 03, turned out that my rotor was rusty, not sure how that happen.<br />Pull the cap and see how it looks.<br /><br />After I cleaned up the cap and rotor, worked better ( but still take it in for a checkup, it may still be under warrenty.) Mine is starting to act up again, will be replacing the cap, rotor and plugs.<br /><br /><br />Good luck!