My primer pump has been on the engine for about 16K miles and I pulled it off a junk engine I had that had a fairly new IP. I'm leaning toward a sticking check valve on the lift pump. I was looking for a diagram for the lift pump but none was to be found in the FSM.
I'll see if I have a spare lift pump somewhere and swap it out. Otherwise I'll see much of the current lift pump I can disassemble and clean.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012