OzRob
Member
- Sep 28, 2017
- 39
- Boat Info
- 2007 Sundancer 355 (Int'l Model of the 320DA)
RayMarine C80
BowThruster
2 x 100W Solar Panels
- Engines
- Mercruiser MX 6.2 MPI with V Drives
Raw Water Cooled
While waiting for the new parts, and having nothing better to do, I thought I'd investigate as to why the high pressure pump in the module wasn't working.
After carefully cutting off the rolled over end on the bottom of the outer casing and pulling out the innards it looks like this: (the little metallic ring near the end of the casing is the bit that was cut off)
From left to right the parts are:
- Plastic top with brushes and outlet nozzle
- Magnet casing
- Magnets
- Armature with 5 little drive prongs that engage in the inner gear
- Pump gear spring steel spacer thingos and wear disc
- Pump gears
- Pump body
The gears and pump internals were totally clogged with what I will call "mud", for want of a better term, no doubt a product of the oxidation of the top of the module.
I cleaned everything and re-assembled it:
Without the rolled over part of the outer casing I had to hold it all together, but when I applied power it ran just fine.
So . . if this pump has been inoperative then presumably the Facet pump alone has been providing fuel to the injector. The flowrate would have been adequate as the Facet has to provide this to supply the high pressure pump under normal conditions, but the pressure would have been considerably less. Maybe just enough to keep the genset chugging along at very low revs, as it was.
A fascinating aspect of the design is that the fuel actually is discharged from the pump body (via the little square hole visible just below the right hand screw in the 3rd and 4th photo) and passes up through the motor before exiting through the nozzle in the blue plastic top. Thus the rotating armature and the carbon brushes are surrounded by the fuel as it passes up though the motor. One way to keep the motor cool, I guess.
Anyway, it was just an academic exercise - the pump is now worthless without the rolled bottom edge of the casing to keep it all together and seal it, but it was fun to see how it all works, and to understand why it wasn't!
After carefully cutting off the rolled over end on the bottom of the outer casing and pulling out the innards it looks like this: (the little metallic ring near the end of the casing is the bit that was cut off)
From left to right the parts are:
- Plastic top with brushes and outlet nozzle
- Magnet casing
- Magnets
- Armature with 5 little drive prongs that engage in the inner gear
- Pump gear spring steel spacer thingos and wear disc
- Pump gears
- Pump body
The gears and pump internals were totally clogged with what I will call "mud", for want of a better term, no doubt a product of the oxidation of the top of the module.
I cleaned everything and re-assembled it:
Without the rolled over part of the outer casing I had to hold it all together, but when I applied power it ran just fine.
So . . if this pump has been inoperative then presumably the Facet pump alone has been providing fuel to the injector. The flowrate would have been adequate as the Facet has to provide this to supply the high pressure pump under normal conditions, but the pressure would have been considerably less. Maybe just enough to keep the genset chugging along at very low revs, as it was.
A fascinating aspect of the design is that the fuel actually is discharged from the pump body (via the little square hole visible just below the right hand screw in the 3rd and 4th photo) and passes up through the motor before exiting through the nozzle in the blue plastic top. Thus the rotating armature and the carbon brushes are surrounded by the fuel as it passes up though the motor. One way to keep the motor cool, I guess.
Anyway, it was just an academic exercise - the pump is now worthless without the rolled bottom edge of the casing to keep it all together and seal it, but it was fun to see how it all works, and to understand why it wasn't!