Replaced the main and pre fuel filters on my 1984 190D and, what I thought should be very simple, now has me scratching my head.

The vehicle will not start and has all the symptoms of air lock in the fuel system. According to my Chilton's manual, the 1984 190D is self priming. I do not see a priming pump.

Have confrmed that the fuel pump is pumping and that the main filter is full of fuel. There is some air in the pre filter but I don't think that is the issue.

All ideas are appreciated.