Tractor Repair: fuel pump on International 444 diesel, fuel inlet, injector pump

Question
I was bushhoging and the engine was surgeing, then just quit, I changed fuel filter and bleed all the line and pump, cranked the engine and used a litte starting fluid and it took right off, mowed about 2 hours and quit for about, 30mins, came back to start and it just cranked and cranked, used a little starting fluid and it took off. Made about 2 rounds with the tractor and it just quit again, What do you think, maybe the injector pump or what? It is a 1973 model, have never had this kind of problem before. Any help before I take the pump off and try for a rebuild would be great.

Answer
You need to check for something plugging the fuel inlet line from the tank. Take off the line from the filter housing and remove the fuel cap. Use compressed air and blow back through the line. Reassemble and prime the system. If this works for a while then time to drain and clean the tank. If not, maybe the pump.