Several suggestions for Maine Sail
Relocate your electric lift pump to be positioned between the tank and the first filter in the delivery line series.
1. this will change the fuel system to a 'pressure motive' from a vacuum motive delivery system
1a. The hydrodynamic benefits will be the fuel filters will last much much longer working in 'pressure mode': the maximum vacuum generated by a single stage 12vdc pump is approx. -3 psi which is not much 'force' to make a filter work. In pressure mode the same pump can or should be able to deliver up to (+)10-12 psi .... which will translate to the filter being able to extend its online service life (dirt capacity) significantly. Pressure mode delivery will enable you to quickly force oil into the filters after a 'changeout' (it takes some time for the 'new' cellulosic filter media to 'wet out' and 'release' all its entrapped air).
Filter 'geeks' will also state that in pressure mode the debris will tend to form ON the media which less restricts 'throughput' than vacuum feed which tends to deposit debris IN the filter media thus promotes a filter to more quickly 'choke'. Pressure feed allows the filter to filter 'more volume', operate at much higher 'differential pressures' (difference between inlet and outlet pressures) and also last a lot longer in service.
2. DOWNSIDE. A pressure feed system will require 'bombproof' lines and connectors, double flared connectors as a minimum - compression fittings are inconsistent with pressure feed requirements.
A vacuum motive system will automatically shut down the engine when a fitting, etc. 'sucks air', a pressure feed system with a loose fitting, etc. will fill the bilge.
Most small and above commercial marine fuel applications are usually pressure feed. Recreational boats typically have vacuum feed system probably due to .... the boat builder needs to cut costs.
3. all filter usage should be 'profiled' (recorded data versus time/gallons used) by the usage of vac/pressure gages (WOT rpm vs. filter gage pressure) so you know WHEN to change the filters and to monitor the 'quality' of the fuel IN the tank (by continuous historical record). The flow curves (gph vs. inches of inches of Vac or PSI pressure) for most Racor filters are found on the
www.Parker.com website ... just look up Racor, etc. When the 'flow' gets to approx. 120% of 'maximum engine consumption' (engine manufacturers chart) according to the differential pressure (vac. or pressure) on the filter flow chart data THEN you change the filter (but still have 20% filter reserve capacity left). Simple speak: when the filter's pressure/vaccum is at 80% of the corresponding volume flow (gph) on the Racor flow/vac or pressure chart, then its time to change the filter. Why needlessly throw away expensive filters that have little captured debris; OR, you wind up 'power-puking' into the bilge when changing a filter in a raging seaway because you didnt know what was going on ... use the gages to monitor. That stated, It is however a good idea to change filters on 'regular maintenance basis', as such filters are made from 'resinated' cellulose fibers which can 'digest' and become softened with long term contact with ... water (emulsified water in the oil and 'free' water). One year filter service life is about as good as it gets; as, if the system has 'any' water, the potential quickly goes up for a 'filter breakthrough'. If you dont have guages youll never ever know that you even had a 'breakthrough' until you HAVE to change a filter at a VERY BAD time. (breakthrough: the gage will suddenly show less vacuum or pressure versus a reference engine rpm).
4. Routine tank cleaning (physically scrubbing the walls/internals) is the BEST remedy for trouble free fuel systems. Most refiners and large scale users typically recommend a minimum of 5 years interval to remove the 'formations' caused by resin forming funguses and bacteria. The typical 'fuel problem' is the thick formation of 'resins' and dead cells (biofilm or calcyx) which occasionally 'breaks loose' from the tank walls ... and instantly chokes the filters. Many of these particle are 'soft and deformable' and can easily be extruded through such filters. Some hold the opinion that many of these 'extrudables' are the main cause of 'coke' in the exhaust system (injection elbow). The best way to prevent such formation is to occasionally clean the tank and use a simple on-board small fuel polishing system that continually runs when the engine is on. Such recirculation polishing will by the mathematics of 'turnover': a. remove most of the microorganisms hence their capacity to form 'resins', b. will very quickly restore the tank back to acceptable particle levels IF a section of biofilm, etc. does break loose, 3. will VASTLY decrease the need of the 'primary/secondary' + 'engine guard filter' as 99% of the 'filter work' is done in the 'recirculation polisher'. The moral here is dont depend on filters to do your 'routine' tank cleaning ... filters only stop debris from entering into the engine. Remove the debris before it gets to the filters !!!!!!!
5. a 12 vdc pump mounted near the tank, with a momentary push-button applied to energize will allow effortless 'bleeding' of the entire fuel system all the way from the tank to the high pressure pump.
CAUTION/WARNING
Modern 'blends' of biofuel can contain 'reclaim' made from re-refined cooking, etc. oils. Especially if the reclaim % is above 5% then the old standby BUNA/Neoprene hose, pump diaphragms, etc. may no longer be suitable. Buna/Neoprene can become softened, can swell and weaken in the presence of the organic acids that are found in 'reclaims'. The potential of fraud of someone 'diluting' fuel oil with 'reclaim' in a fiscally hysterical fuel market is not to be ignored. This alone would make the use of 'squeeze bulbs' not applicable for a safe system. I doubt if the 'boat regulators', etc. will become aware of this chemical incompatibility for many years.
Hope this helps.
;-)
