Look at the wiring first to see if it appears to be properly grounded. Don't stick your hand into a flooded sump to lift the float. LP is 1.53 the weight of air. If there is a leak, they may collect in unventilated spaces below grade, and reach explosive concentrations. A spark could ignite the gas.
Some crawl spaces are very large, and are difficult to move around in.
It is possible to get disoriented, stuck, or even lost. Make sure that you know where you are and have a good flashlight. In old houses where galvanized piping has been disconnected, watch for loose or cut off pipes that might fall and hit you or block your way. Stay oriented on where you came in, so you can get back out. Give your client or whoever is with you an estimate of how long you expect to be in the crawl space.