Originally Posted by sv.Crake
Thanks Stu. Can you link me to those threads. I've been hunting but not found them.
My reply #2 was just that, I do not understand this^^^.
Here's the text of what I wrote in that link:
On September 20, 2019, I was motoring back from a few enjoyable nights at my favorite local anchorage when I experienced a fuel starvation issue for the first time in my boat. We have sailed Aquavite
since 1998. The engine simply sputtered and died, would restart after a few minutes and die again. There were no previous issues, ever.
I replaced the fuel pump. I had corrected the fuel flow from the tank to the primary when we first got the boat. I replaced the primary filter last year. I replaced the secondary filter. When a test sail proved fruitless, I had to go further.
I remembered reading the Racor
manual ages ago about a "fuel check valve" that's cleverly hidden at the inlet of the filter housing. It's called a ball check valve, which keeps fuel from emptying from the filter if the tank is below the filter, which makes sense. I undid all the new fuel hoses I'd just put in (!) for the new fuel pump and unscrewed the primary filter and bowl, and then removed the housing.
The filter housing is the Racor
220 / 225 Spin On Series, using the ubiquitous Racor R24 Series filters, installed on most Catalina
34 boats. On the top of the housing is a large plastic screw, identified in the manual’s first page diagram as the “Flow Check Valve” and on page four, it is replacement part list Item 3, part # RK20011, “Check ball valve and plastic cap.”
I unscrewed the check valve plug
and O ring and found 33 years of accumulated tiny black particles that kept the ball from rising and allowing fuel to flow. It didn't take much crud at all to stop the ball from working properly. It's a very small chamber about the size of a quarter and the ball is smaller than a dime. There was actually no "bad fuel" issue, just decades of what I would consider to be normal stuff found in any liquid. I cleaned it out, and things are back to working properly.
If you have fuel starvation issues, or anything that reduces your engine RPMs, consider this obscure fuel filter
housing ball check valve as part of your diagnostics.
PS The Racor 500 series housings do NOT have check valves in the housing, but the manual says to install a check valve in the inlet of your fuel hoses to the housing if your tank is below the filter.