Two Qestions

[woodnknots]

First, how do I tell what size/pitch prop is on my motor? I have a 1990 90 hp Force.

Second. I have only had my boat for about a month or so now, and just put some seafoam in the gas tank and took it out last night. On the way out, at full throttle the motor ran fine, but on the way back in (sat with motor off for about 1hr), it started to intermittently lose power, kind of like it was missing. I pulled two out of three plugs when I got back to the dock, and the middle plug was pretty black. Am I just fouling my plugs because the seafoam is doing it's job, or is there something I should be checking out?

 

[Docdoc]

Re: Two Qestions

The prop should have markings indicating the size and pitch somewhere, probably on the hub. Sounds like the seafoam is doing a good job and moving the carbon to the point it is fouling plugs.

 

[woodnknots]

Re: Two Qestions

I found the number 15 on the side of the prop, is that the pitch or the size?

 

[steelespike]

Re: Two Qestions

If the number is a reference to size it would be pitch.
Measure the radius and multiply by 2 for the diameter.