Just changed my fuel filter and had a few questions. What is the nipple on the bottom of the WIF sensor for? It looks like a hose should go on it. On Eric's pic post as how to do it he said disconect the 2 wires from the sensor,I only have 1?. What would happen if you didn't plug the wire back in? I ask cause mine was hard to get to and I question if it's together good.It started right up and ran fine in the drive for 10 min. Also when I removed the old filter no rubber center washer came with it. From his post and the 75 or so pages that followed it most of the problems guys seemed to have was that it stuck up in there and they couldn't get there new filter on as it was double. I looked up in there with a mirror as I did it from above and for the life of me could not find a washer.Is it possible there never was one? It was a Izsu filter,the correct one. I went ahead and put the new one on and all seems well. 1st time doing this and am just concerened if all is well,wouldn't want to take off with camper and have a problem down the road...It's a 01 GMC 2500HD. One more thing,I only use this for travel,if it idled in drive for 10 min. and all seemed ok can I assume all is ok? or dose the pressure increase as you drive (more than at Idle in drive)

Wif sensor is 2 wires but maybe it looks like one since in a jacket surrounding both. The plug is 2 pin. The nipple thing is the water drain valve if you get water in the fuel in the filter. No idea on the missing o-ring. I would say issue would be raw fuel passing past the filter straight to the engine. Not good on injectors if bad fuel was to enter or water.

Brian

If that rubber piece was still on the filter housing it would have been hard to get the new filter to screw on.