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Old 03-09-2020, 10:41 AM   #37
Transaxial
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City: Edmonton area/Nanaimo BC
Vessel Name: Soul Fisher
Vessel Model: Palmer
Join Date: Jul 2016
Posts: 101
Old school diesel engines generally had very low return flow rates. I recall in general that the Detroit 2 stroke engines ( like all 53, 71, 92 series) had a lot more flow than a typical 4 stroke in those days. The Cummins PT fuel systems also flowed a lot more back to tank which created a lot more heat in the fuel tanks. That flow was designed in to those unit injectors, which was for cooling the injector, along with the usual function of purging air from the system. With most of those older engines, many naturally aspirated, cooling was not a big deal as they only produced 120 hp from a 400ish cu in engine. I know the OP was talking about a 120 hp FL but there is a huge difference in return flow between those and say a high hp 6-71, and an even bigger difference when talking about newer high pressure common rail engines, intercooled and aftercooled, that are producing 350 - 400 hp from a similar cid engine. The hpcr engine returns a lot of fuel, partly because it can burn 20+ gallons per hour and needs a steady supply, but it also needs to cool the injectors with high rates of return fuel.

The best thing about Racor filters is being able to see if any water or solids get into the clear bowl if you have enough light. Great idea to add a little light behind the bowl! In the truck and heavy equipment world, a lot of these "bowl" style filters are being removed from systems because they are so prone to leaking air into the fuel and since they are designed as a "suction" filter it does happen. Not a problem on a polishing system. I would lean toward a 1 or 2 or both selector using a pair of Fleetguard FS1000 with water drain. So much quicker and easier to change on a rocking boat which is when you will have to do the emergency change. Read Tony Athens articles.
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