Detroit 12.7 Hard Start and No Power

A fine hair line crack will cause a slight loss of power and fuel efficiency. A big crack will result in huge power loss.
For your codes just Google them. Type in what ever your code is plus the ddec number. For example, My 02 engine is a ddec iv.

 

I thank code 46 is low voltage from the main battery to the ECM. There may be two hots and two grounds from batteries. That could totally be your problem.
Also sounds some what like a bad seal under an injector getting combustion into the fuel rail. It is hard to put a finger on the which one because it effects multiple cylinders. Look in the fuel tank with a light. Is there a lot of bubbles or foam going out of return line?
Have seen severe algae restrict lines on off road equipment. Search algae, top right.
Is that Malawi, South Africa? How far is Sears? You can test for a dead or weak cylinder by manifold temp. for the first few minutes after cold start by touch. Then with a spray bottle with water or possibly a crayon or candle but the gun much better.
Also search scan tool. There are some inexpensive ones the will allow you to clear codes and watch what is going on while driving.

 

Also, codes on the check engine light are inactive codes. The red stop engine light shows active codes.

 

exhaust gas leaking past inj will turn fuel black

 

Mine was doing the same thing. not every symptom as yours but my fuel & filters were turning black & sootty. my shop guy told me inj seals & the head needed to be taken off, however there is a aftermarket kit that detroit DOES NOT sell but he bought some kind of kit that went on the ends of the inj & said lets try that. so far my mileage on my fuel filters has doubled & the filter is clean as is the fuel, though it may be hard to tell this soon, but so far so good. so there is a aftermarket try to remedy at least 1 of your problems. talk to your mechanic & mention what I said . good luck.

 

Those are just some possibilities. The most affordable solution is to research, test, and fix the problem the first time. I have repaired some by installing injector seal kits and replaced injectors if the lower seal area did not look perfect.
Some other people on here know much more about these engines then I do. If you take the time to research the problem and test things they would be more inclined to answer your questions. No one here has a magic crystal ball that I have found yet.
I used to play darts a lot but found I was not very good at the game and it cost me a lot of money. Isolate the problem and fix it. If you are not going to do that you are probably better of to take it to someone that will.
If you are working on these engines and can not clear codes you are probably throwing a lot of darts in the dark. Just my opinion, good luck.