Development continued throughout the war. The PB2Y-3, featuring self-sealing fuel tanks and additional armor, entered service just after the attack on Pearl Harbor and formed most of the early-war Coronado fleet. The prototype XPB2Y-4 was powered by four Wright R-2600 radials and offered improved performance, but the increases were not enough to justify a full fleet update. However, most PB2Y-3 models were converted to the PB2Y-5 standard, with the R-1830 engines replaced with single-stage R-1830-92 models. As most existing PB2Y-3s were used as transports, flying low to avoid combat, removing the excess weight of unneeded superchargers allowed an increased payload without harming low-altitude performance.