Regarding my tractor's possible issues with the injection pump!

[CalG]

A lot of folks keep advising for a compression test. Why? What are the signs it needs a compression test and have you purchased the tester and adapters to take the test?
An engine with low compression will show signs that it is low such as excessive blowby, or excessive oil usage, and yes hard starting.
But how long ago was the injection pump or injectors serviced? A pump that leaks internally will not produce enough pressure to pop the injectors to start. Injectors with a poor spray pattern will not atomise the fuel enough to start. Of course starting can also be affected by plugged fuel fiters or inadequat fuel supply, or water in the fuel system.
Is the air filter clean, are the valves adjusted correctly?
Electrical connections and battery condition also affects starting.
For the twenty years I worked with engine you can tell a lot of the engines condition by listening to the engine. Does it turn over even? or is there a cylinder that turn over faster and the the engine slows down, then speeds up and so on. Does run smoothly.I was aked by a manufacturer for a compression test and could not find an adapter to test it, and they could not provide one. Turned out to be water had gotten in the fuel system and killed the pump.
A lot of things can be checked before you go out and buy expensive tools, of course you just may want to add to your toolbox.
Band aids and work arounds don't do anything to fix a problem and may cause more issues than it fixes.

Though all your points are good, how does anything change when the 24V battery is used as a starting aid? The only thing I can see that changes with the 24V battery is the cranking speed.

Do injector pumps really work that much better when operating 50% faster?
How will a dirty airfilter be influenced by cranking speed? Seems like that problem would show up when trying to run the engine at full rated RPM.

This all gets so confusing for someone trying for logic.

(Even though the solution to a problem with tractors often does not follow the description to a logical conclusion)

 

[Bentrim]

Though all your points are good, how does anything change when the 24V battery is used as a starting aid? The only thing I can see that changes with the 24V battery is the cranking speed.

Do injector pumps really work that much better when operating 50% faster?
How will a dirty airfilter be influenced by cranking speed? Seems like that problem would show up when trying to run the engine at full rated RPM.

This all gets so confusing for someone trying for logic.

(Even though the solution to a problem with tractors often does not follow the description to a logical conclusion)

24 volt when applied to a 12 volt stater increases the starter speed just as 12 volt applied to a 6 volt starter. Years ago people had a choice of an 8 volt battery to help those slow cranking 6 volt tractors, no changes were needed except to change setting of the voltage regulator. To double the voltage takes a lot more work and parts.
The problem I see is that to change to 24 volt you have to upgrade all electrical components. Wouldn't it be cheaper to fix the problem?
As for the air filter if plugged it would allow the engine to crank fast (can't get enough air) and would disturb the air fuel ratio.
A rotary type injection has a head assembly, basically a block with a rotating block inside, think of a distributor on a gas engine. There are no seals used within the head and if the clearance becomes to great fuel will leak out between the rotor and the head, not sending enough to the injector to open it. When the pump is sped up the leakage is still there but has a shorter time to leak and delivers more to the injectors. Inline pumps use a separate pumping element for each cylinder and can fail for the same reason, too much wear between the piston and barrell.
Knew a fellow that had a tractor that did not start when it was hot, he know the pump was the problem as it was leaking internally and would not send fuel to the injectors. His fix was to dump a bucket of cold water on the pump, tractor would start then. NOT a recommended fix as it could cause the rotor to seize inside the head----.