Boat has Analog speedo gauge. Pilot tube to sensor on motor sending signal to gauge, I located the pilot tube going to sensor and can blow thru line, no restriction. Trying to figure out how to test sensor with meter . Trying to figure out if its the gauge or sensor. The pilot line going to sensor has a tee on the sensor one side of the tee has about 12" of extra tube with cap on end, When I remove the cap I can blow thru line and feel the air coming coming from the pick up hole on LU.