Pulling the wire sends it full scale, otherwise it tends to twitch to full scale erratically every now and then. Wiring looks clean. Engine ground OK, but bypassed anyway as a test--no help. Factory oil filter replaced about a month ago, twitch didn't appear until about 2 days ago.
Do I need to drain the oil before swapping that thing or is there a check valve behind it? For 13 bucks I'll swap it before I'll bother pressure testing the pump.