Bosch type injector pump adjustment

[doc g]

I have NL 20 KW gens on my boat .They have Bosch type inline mechanical injection pumps . I was told by NL that you set the rpm and the rack in the pump sets the fuel setting to match , much like DD racks adjust fuel to match the throttle setting. I am having a problem in that the rack is not advancing the fuel as the load is increased on the gen. Is there an adjustment that can be done or does the pump need to come off and go to the diesel injection shop? Any advice appreciated.............................Pat

 

[Avenger]

Check to be sure that the throttle lever is all the way up against the speed setting screw. If it's holding 60Hz no-load it probably is okay. Other than that I'd be more likely to suspect a fuel system issue. Are you sure that you have an adequate fuel supply? Are the filters clean, is the fuel pressure good etc.?

A part number off the injection pump would be helpful so I know what kind of governor it has.

 

[krush]

What Scrod said. All you can play with is that throttle lever that is usually fixed in position by bolts. The rest is taken care of internally and really not repairable by any normal human.

 

[doc g]

The NL # is 131016950. It has fly weights (?) in the gov.I don't know if that helps . It also says that it is rated at 1800 +/- 3-5%. The 1' and 2' filters are new .........Pat

 

[Avenger]

Okay, mechanical governing at 3-5% sounds about right.

I'm sorry, but I can't cross the NL number. NL doesn't make the engine, so they are probably re-numbering the engine manufacturer's part number, who re-numbered the injection pump manufacturer's part number.

NL likes to use Ishikawajima engines, which usually use Zexel injection pumps, but I couldn't cross it there either. There should be a data plate on the injection pump itself with the number. Failing that, a picture would probably be good enough for me to ID the type. Actually, since I won't be back at the shop until Monday, a picture would probably be better.

Back to your problem. Can you give us some more specifics on the problem, how much is the RPM or frequency drop? Does the unit holds RPM consistently under no-load? How much load can it carry, or does it just go right on its knees when you turn on a light? Is there something specific that leads you to suspect the pump?

Check the shutoff lever to make sure that it is fully in the run position. If it isn't, it can limit full-load delivery.

Other than that I'd still suspect fuel supply problems. It may be necessary to find a place on the injection pump inlet where you can put a pressure gauge. A related possibility is a failed overflow valve which is the pump's supply pressure regulator. Again, a pressure test may give us a clue.

 

[doc g]

So , I put a pressure gauge in the line to the pump? What happens is when I try to charge the inverter bank the inverters drop out as soon as the freq/voltage drops below what they like (58 Hz min 108 v min). As long as the fuel press to the pump is within spec it's the pump itself??? ..........Pat

 

[Avenger]

Let's jump off that bridge when we get to it....

Yes, tee in the pressure gauge at the injection pump inlet after all filters. Check the fuel pressure when the problem occurs. Does your manual have a spec. for fuel pressure?

Also, don't forget to look at the shutoff linkage/lever and make sure it's in the full run position.

Do you have a frequency meter or a tach available? You may be running a bit low on frequency to start with i.e. 59Hz. If the load drags it down 1 Hz it will cause the inverter to trip out. You may have to run 61 or 62Hz no load so it droops into spec with a load.