F.P. gauge saved me from being stuck on the road

The gas gauge was on empty, but I figured I had enough to go to the grocery store first, then to the gas station. So I'm heading to the store when the fuel pressure gauge starts going nuts. No engine stalling or other indication except from the gauge. I guess there was enough gas in the float bowl to keep it running although it was intermittently sucking up air. Went to the gas station first instead, put some gas and no more problem.