Okay a fuel injector is about 40 to 50 pound in wieght and about two foot long has an opening pressure of about 380 bar and an operating pressure of about 1000bar at peak injection pressure. It has some of the most accurate machineing on the ship. (did you know that a VHS video head is one of the most accurately machined compnents in mass production). Some engines have two some have three dependant on age and design etc. Apart from a strange jap design with three exhaust valves and a central injector and older loop scavenged engines that had a central injector.

the injetion pump is a real complex piece of work but very clever in its design. i shall try and remeber to post a picture of one but this is how it works.

A normal injection pump for a small diesel (500bhp and up) is a jerk pump where you have a plunger going up and down in a barrel with a hole (spill port) on the side of the barrel and a helix is cut into the side of the plunger and by turning the plunger you can control when the hole is uncovered to spill presure and control injection.

On the sulzer/wartsila it is totally different you still have the plunger but it is plain and you still have the barrel but it too is plain. On top of the cam follower there is a yoke onto which two arms are connected which go up and down with the cam and plunger.
These arms pivot on two excentrics one per arm the left one is pivioted in the middle the right one at the end. On top of each of these arms the is mounted a rod which goes into the fuel pump and lifts a valve off its seat when it goes up.
The left one is sat on the end of the arm and control the suction valve.
the right one is sat in the middle of the arm and controls the spill valve

As the follower climbs the cam the suction valve will drop down onto its seat and seal the pumping chamber and injection will begin when the pressure climbs above the opening pressure of the valve. Then the follower will continue to climb the cam which at the same time raises the spill valve control rod which will then come into contact with the spill valve and lift it from its seat and injection will finish

it might help if you give above a quick sketch or wait till i post a drawing.

the clever bit is the control the two exccentrics gives us the one on the spill side is used to control the end and therefore the amount of fuel injected the suction one is used to control the start of injection and therefore we can alter the timing of the injection whie the engine is running.

A similar idea is being used to control the exhaust valve to give variable compresion which has advantages. As you will of seen with saab and their new variable compression head which i really like.

There is alot more to injection than i have descibed above as there is strange things like wave reflections etc to deal with as well as things like fluid compression etc.

As to amount of fuel used it is about 76tonnes a day at full power but that does include a generator running 24hrs a day. Which works out about 0.26 pound of fuel per horse power hour i think.