A system for precision liquid delivery includes a gas reservoir having a known volume. The system has a tightly load-coupled pneumatic driver (a “TLCP driver”) that is configured to receive input power to cause the TLCP driver to move gas into the gas reservoir to produce a gas drive pressure. A valve is configured to couple the gas reservoir with a fluid reservoir having an unknown volume. The valve is further configured to selectively isolate or pneumatically couple pressures in the gas reservoir and the fluid reservoir. A gas-fluid interface couples pressure in the fluid reservoir to pressure in a fluid path. The fluid path is configured so that the fluid drive pressure driving the liquid in the fluid path is substantially the same as the fluid reservoir pressure. The system also has a pressure sensor configured to detect pressure in the gas reservoir and/or the fluid reservoir.