Fuel / Water seperator filter
 

I'm just installing a whole new fuel system ( except tanks ) to a freshly rebuilt 94' Johnson 150. Installed the Stainless water seperator bracket, looking through my Jamestown boatbuilding cat. trying to choose the right spin on filter. 2 questions :

1. read somewhere that the 10 mic filter is for newer motors with higher pressure fuel injection and the 21 mic is for the older motors. asked a local marine mechanic and he said everything is 10 mic. ( not crazy about this guy in the past ) Does it matter ?

2. Looking the filters up in my Jamestown Cat. a little confusing, most of the Sierra filters and Raycors say they are for Yamaha and Merc, how do I know which one to choose ?

I always thought the smaller the microns the better. I have a 10 micron on my 86 yamaha and have no flow issues.

I'm using Moeler filters on both my Johnson and my Mercury engines. Both are 10 microns. The Merc is a 1989 and the Johnson is a 1991. Never had any problems with either engine with regards to the fuel. I agree with RWilson2526, the smaller the microns, the better. Just as a general comment, it's been my experience that if you look in stores, most stores stock more 10 micron filters than any other type. Must be a reason.

As far as the catalogs go, unless the filter spins on to a fitting on the engine, or is somehow part of the engine, all filters are for all engines. We're talking about units that bolt to the side of your boat, usually at the splashwell, and filter the fuel as it comes from your tank and before it goes into your engine.

Thanks , that's what I wanted to be sure of.

there are two main differnet spin on filters available. The standard(if you want to call it that) thread size for Merc, Yamaha, Aqua Power, Sierra, Moeller, and just about every one else out there. then theres the OMC/Crusader filter that uses a larger threaded hole in the filter. If you compare teh two, you will see the difference. Racor has a whole otehr set of thread sizes and filter designs, but I'm talking about hte generally used spin on fule filters here. There are several sizes available in lengts, from the shoft late model Merc to the extra long Yamaha. If the box says "high performance" on it, its generally the 10 micron filter. Figure out which one you are using, most of them are the Merc/Yamaha size. Then get the 10 micron filetr with teh maximum lenght you can fit on the filter head. Once you figure out which one you need, buy at least three of them to keep around, one to install, one to keep on board(in a dry space) as a spare, and one in the shiop tp replace the one you used on board when you need it(weekend saver). If you use Racor filters, then it gets a little more complicated and expensive, but don't get me wrong, racors are great filters, they just cost more and people don't replace them as often as they should because of the price