I have a 95 e300d that is getting air in the fuel lines. I am replacing these lines and or rings one at a time, but it seems like they are all leaking at once and no problems before. It also looks like the delivery valves are leaking slightly too. Would a bad lift pump allow fuel to drain back to tank and suck air into the lines in a bunch of different places all at once? I suppose I should replace this part since it has 331k on it. Is the readily available Bosch one ok? Thanks!

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1990 300d 2.5 turbo
1995 E300d