Transaxial
Senior Member
I like your approach kapnd, to always be learning and looking for a better way of doing the "same thing". But the world is changing. Fuel is totally different now. Storage time for fuel is very short, specially when it is contaminated by any source of water. I think water separation at the tank sump is the first line of defense. Water settles to the bottom of the tank best while the boat is resting calmly at the dock so why not get rid of it, if there is any, before you head out and stir it up. The larger and coarser filter, be it Racor or whatever, has a much greater area to filter out contaminents without plugging so should be the first filter in line. If a 2 micron filter was first in line it would plug long before the big 30? micron. But the second or third place 2 micron now has much less big junk to filter out so can do its job better, and last longer on the small particles. It only matters if you have lots of contaminants in the fuel, but that might be what saves you in a situation where you take on a bad batch of fuel. I like having gauges (that work!) in any fuel system plumbed simply with a line right to the instrument panel so it can be monitored just like temperature or oil pressure. Vacuum gauges should be after the last filter. If the gauge is on the big Racor with 30 micron element, it will not read the plugged up 2 micron final element. That could be why some do not see a vacuum increase. It does not matter what the flow rate to the engine, if the filter is plugged, there will be an increase in the vacuum. Some engines like Cat have a charge pump on the high pressure pump that sucks fuel through the primary filter(s) and then pressures it through the secondary or final filter at pressures of 80-100 psi. Those engines usually run a pressure gauge on the dash so you know if you have normal pressure to the engine. A very good system. There seems to be a weak link in some of these boat fuel systems in that there is no priming pump to aid in refilling filters and purging air. Does anyone add a small Carter or Stewart Warner 12V pump that can be manually run for purging all the air from a system any time it is opened or even if it has sat for a long time and had some back flow to the tank? I believe these pumps flow free flow when they are stopped so only need to run when you want them to. Kapnd spoke of a simple squeeze bulb primer that may be very effective for purging air and refilling filters and lines. Cat usually had some type of a manual plunger pump incorporated right into the filter base of the secondary filter that enabled the operator to refill the filters with FILTERED fuel just by working the plunger up and down. This was very clean filtered fuel and eliminated the use of very questionable fuel for filling filters that came from a jerry can or other unfiltered source. That fuel that you just poured into your new high quality fuel filter gets sucked right into the high pressure pump, because it is inside the filter, past the filtering process. That is just not an acceptable procedure, specially on new high pressure common rail systems. That is why I would incorporate a small, intermittent use charge pump for purging the fuel system after servicing. Whether it is manual on electric it does an important job. I am not here to criticize any one or to question how someone has done it in the past. I have been working on, and operating diesel engines for over 50 years and realize that I have not always done it right, and therefore I am always interested in looking for a better, simpler, more fool proof way of doing things. If it makes my engine run better, longer and with less problems, I am the first one in line to admit I was wrong and I would like to try the better way. It has always come out of my pocket when I screwed up so I am pretty keen on not having extra expenses. Who says you can't teach an old dog new tricks!!
