wont start

[exfarmerbrown]

My 1990 W250 wont start . It was running fine and i shut it off and when i went back it would not start. But you can put just a little gas down the intake and it will start and run all day. But it only starts after you get it spinning and let off the key

Thanks

 

[PaPitt]

My 1988 318L i NORMALLY turn just the key on several times for about 20 seconds Then turn the key off & Then cycle it back to on, I do this 3 times I think it pumps fuel up into & Priming My system . Then my truck cranks better .
.........
......I expect I have a weak fuel pump.