Wiring on that model is simple, the only safety is the clutch pedal, and if it's cranking there isn't anything else electricly that the engine needs to run.
If there is fuel getting to the side of the injection pump then it's probably fine, that system does not move a whole lot of fuel.
Does it have a clean filter and when you remove the filter housing and turn on the fuel does fuel flow out of it?
Reinstall the filter and housing, leaving it loose, open fuel and bleed out air out of housing then tighten, open bleeder on side of injection pump, crank several times to get all air out from line between filter housing and injection pump.
Crack all three line nuts on the top of the injectors, wide open throttle, crank till you get clean non bubbled fuel (this can take a lot longer than most think), tighten line nuts.
Turn the key in reverse, does the glow plug indicator glow red?
if it does not , you need to service it as it's not sending juice to the glow plugs on pre-heat.
Yes you can still get power to the plugs on crank as it does not flow power through the dash indicator but without pre-heat working they will not get hot enough to work properly.
