Just changed engine oil on my newly acquired truck and this time on Start up the water in fuel light come on. I'm going to change the fuel filter I found under the cab passenger side. Will I have to bleed the system of air?
Does the filter have a water drain? My F800 doesn't have a water sensor in the primary filter but what I do is warm the engine up good, stop the engine, drain the water out of the primary (catch the drained fuel in a glass jar, you will know when the water is out) restart the engine and when you see oil pressure, open it up. should run any air out through the return system. I don't have a tilt hood and it's a pita to pump the hand primer. This usually works for me.
Yes this filter has a drain on it. I'll do like you say but still would like to change the filter. Maybe there is a hand pump on this truck.
There should be a primer pump on the side of the injector pump. Again warm up the engine. makes it much easier to start after changing the fuel filters.
Warm up the engine, remove old filter, fill new filter with fuel, install, restart engine and hold at 1200 rpm or so. It should run the air through.
It sounds like you may have some air in the system. Is there a primer on your fuel transfer pump? The transfer pump must be on the driver's side of the engine, just below the fuel filter. Line comes from the fuel filter in an inline pump unit must have a banjo, which has a 10 mm screw at its outlet. Loosen that and try to prime the fuel system manually. It could anything else, but from this point it will a nice start.
I warmed up the engine then changed filters and had no problem. I filled the filters with diesel first. Engine missed a little bit for awhile then evened out.