A method including positioning a downhole acquisition tool in a wellbore in a geological formation; performing a pretest sequence to gather at least one of pressure or mobility information based on downhole acquisition from a sample line, a guard line, or both while the downhole acquisition tool is within the wellbore. The pretest sequence includes controlling a valve assembly to a first valve configuration that may allow the fluid to flow into the downhole tool via one or more flowlines toward a pretest system. The one or more flowlines include the sample line only, the guard line only, or both the sample line and the guard line; and drawing in the fluid through the one or more flowlines. The method also includes controlling the valve assembly to a second valve configuration. The second valve configuration is different from the first valve configuration and may block the one or more flowlines from drawing in the fluid.