Sunday, August 5, 2012

Fuel System Upgrade

It is said that three most common issues with a diesel engine are:
  1. Fuel
  2. Fuel
  3. Fuel
Shindig's fuel filtering system was pretty simple before I redesigned it.  There was one Racor filter/water separator for the main engine and separate one for the generator.  These filters were located close to the fuel tank under the main salon floor.

In rethinking the fuel system design I wanted to accomplish the following:

For the main engine fuel:
  • allow for active and standby filter for the main engine so you can switch filters on the fly
  • be able to service the filters easily
  • read vacuum and pressure on the filters for diagnostics
  • provide electric fuel pump backup to the main engine lift pump
For the generator fuel system:
  • provide primary and secondary fuel filtration for the generator as the generator does not have a secondary filter.
  • be able to service the filters easily
  • provide electric fuel pump backup to the generator's fuel pump
  • fuel polishing capability

This is what I came up with.

Main engine primary/standby filter configuration
For the engine system I moved the single filter from under the salon floor and plumbed it a second filter on a bulkhead in the engine room.  I have great access to the system in the new spot.

The valve between the filters selects the primary or secondary filter and the valve on the top right allows you to select the fuel pump for bleeding the system, servicing filters or act as a backup to the Perkins fuel lift pump.

The compound gauge on top of the primary filter reads vacuum (indication of how dirty filter is) and pressure for when the fuel pump is pressurizing the system (max of about 8 psi)

Generator filters and fuel polishing configuration
The generator system occupies the space under the salon floor where both systems were before. 
I have retained the capability to shut off the feed to either system at the tank (red valves) and tried to leave enough space under the floor to service the two generator filters.

I tested the flow rate for fuel polishing with this circuit and it measures about 24 gallons/hour.  The fuel pump consumes about 3 amps. 

The most challenging part of this project was finding a good spot for each system and locating the oddball Racor and other brass fittings.  I ended up getting the special Racor fittings online here.   The other fittings I found at Grainger and local hardware stores.

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