The largest refinery in the country has cut output by nearly half as it deals with Tropical Storm Harvey, which continues to pummel the Texas Gulf Coast.
A major pipeline carrying fuel to the East Coast is also running at a reduced rate, partly because of refinery shutdowns in Houston, compounding pressure on the nation's energy system.
Gasoline futures rose 6 cents, or about 4 percent, in trading Tuesday.
Motiva Enterprises said Tuesday that its big refinery in Port Arthur, Texas, was dealing with restrictions in the flow of crude oil coming in and products like gasoline going out through pipelines and ports.
The refinery was running at 40 percent capacity, a company spokeswoman said. She said there is some water in the plant and local roads are flooded.
"Although weather conditions continue to deteriorate, Motiva's Port Arthur Refinery remains stable at reduced rates approximately equal to 40% of capacity. Our highest priority remains the safety of our employees and community," a Motiva statement read.
Motiva is owned by Saudi Aramco, the state-owned oil company of Saudi Arabia.
Even before Motiva's announcement, 10 refineries in Texas including the nation's second-largest, run by Exxon Mobil, had closed since Harvey came ashore as a hurricane on Friday night. Several others were operating at reduced capacity. Around 15 percent of the nation's refinery capacity has been knocked out.
The flooding has also crimped the flow of gasoline and other fuels to the East Coast through a big pipeline.
The Colonial Pipeline operator said Tuesday the reduction was due to limited supply from refiners around Houston and storm damage to its facilities in several southeast Texas locations. The company said it dispatched workers to the region.