Merc Classic Fifty Probs.

[duckhunter55]

1987 Merc. Classic 50 45hp. Motor has ran good since i bought it, which has been around 2 months. Last 3 times out, motor would start off for the first few hours running around 5300-5500 RPM. Then over course of the day motor would drop to 4000 RPM and rarely get above that. It would always run good the next time out, but RPMS would drop again. Now motor want get above 3000 to 3500 RPM at all. It felt as if it was dropping a cylinder before once it warmed up, but now its like its just running on 3 cyl. Motor has always pumped good water, so i dont think it overheated. All 4cyl. have good blue spark at home, not checked on water yet. Anybody have any ideas about whats going on. Ignition, shot cylinder, ? All help greatly appreciated.

 

[duckhunter55]

Re: Merc Classic Fifty Probs.

Any thoughts

 

[thefairlaneman]

Re: Merc Classic Fifty Probs.

Im no expert but the first thing you do is some basic trouble shooting. Check compression. Heat build up due to a bad piston/ring/cylinder has to be ruled out. Next rule out any water leaks ( a cylinder burning water will have a very clean spark plug compared to the normal ones. The thing you dont want to find is a bad power head. The cost then will most likely mean the engine isnt worth the fix.