Okay, I think I am on to something here...Yesterday I took a good look at the fuel hoses under the hood and it looks like the guy hooked the supply line straight to the filter, then the line that goes out of the filter (where the out arrow is) hooks into the line that is on the right of the plastic manual pump, then the line that goes out to the left of the plastic pump is looped to the IP. This doesn't make sense to me...Can somebody give me a quick explanation on the correct configuration of the fuel lines..

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1985 Mercedes 300DT