Carbon build Up?

[gunkas]

Could carbon build up cause a loss of 600-700 rpms and a drop of 7 mph on the top end? (200 hour old 1999 mercury 250 EFi) I already replaced the plugs and the motor runs very smooth and it sounds the same. Should I try a de-carb spray or fuel addative shock treatment or head straight to the shop? Thanks in advance, Mark

 

[12Footer]

Re: Carbon build Up?

200hrs may be a bit too late for additives to have much of an effect. But it can not hurt to try it or the spray.<br />If performance picks back up, great. If not, you are out 7 dollars.<br />Do you still have the old plugs? The reason I ask is, decarbon treatments sometimes do strange things to plugs...Best for it to do those strange things to the old set.

 

[ODDD1]

Re: Carbon build Up?

Mark, did you check the easy stuff?<br />a bent prop<br />stays in the water? lots of hair on the hull?<br />half a ton of water hiding in the bilges?<br /> a compression test will eliminate/verify your theory......

 

[gunkas]

Re: Carbon build Up?

Thanks for your replies but during a second look thru I found a loose connector coming off one of the CDM units, thus I was running on only 5 cyllinders. Its amazing how when all the wires are connected, the engine actually works as usuall...Mark