225 pro xs

[dukhntr]

I have a 2005 225 pro xs. Engine has aronud 270 hours or so. It has a rough idle while in gear (hot foot). If it is just idling in nuetral, it's fine. If I put it in forward idle, it coughs and feels like there is some vibration. Feels like there are some cracked out bass in the livewell. It does this at about 700 rpms. If I give it just a little gas, say up to 800 rpms, it all goes away. I checked the fuel filter and it looks bronze in color and there was a little bit of junk in the bottom where the fuel filter screws on. Got a new filter coming.... I just went to change the fuel line the other day and it already had the alcohol resistent lines and they looked brand new. I use quick clean religiously and use sea foam evey couple of trips also. Plugs were replaced less then 25 hours ago and they look good. Did a compression check and all cylinders were 133-135. Any ideas? Would the fuel filter cause this?

[EuropeanAM]

Randy:

There are several potential causes.

However- before you spend a lot of time and effort on this- let's try something VERY simple.

Get your fuel level down to about 1/4 tank (or slightly less)- and try a tank of FRESH 89 octane fuel from a DIFFERENT FUEL SUPPLIER (preferably a NAME BRAND, high-traffic station).

Run this tank of new fuel.... with appropriate treatments, and see if there's not an improvement in idle/off idle running quality.

Degraded fuel octane can have a substantial adverse effect on idle/off idle quality.