As we've discussed in past threads, one of Japan's motivations for the Pearl Harbor attack was to keep the Americans out of they way while they acquired control of the oil resources to their south.
By three an half years later, they didn't even have enough fuel to buy the Yamoto a round-trip ticket.
Why was this?
Was there less than enough oil in Borneo?
Was there a blockade?
Lack of transport? Lack of refinery technicians? Sabotage?
I tried looking up wartime production figures but I couldn't find them broken down by origin.
By 1944 the US navy had set up an impressive submarine blockade of the home islands. Oil was in such tight supply that the Japanese began to ship oil in barrels aboard warships returning home. As you can imagine, this technique wasn't able to replenish oil reserves. The last tanker to reach Japan arrived in March 1945 so that by April the supply officers at Kure were ordering their men to the bottom of the bunkers to hand pump the last reserves of fuel oil to equip Yamato for operation Ten-Go.
In addition to the increasing effectiveness of the US submarine blockade, the Japanese tanker tonnage was only barely able to provide the oil needed for its war effort. Once the US ironed out its problems with its torpedoes, they were able to cut off this bottleneck.
Jonathan Parshall examined the issue of Japan's anemic oil production in an article on his website and Bob Hackett has also published a study on Japan's oil fields on Parshall's website.