If it was sitting exposed, my guess is that element is toast. Either rebuild or good used pump.

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

The delivery valve could be held open by a chunk of dirt, allowing fuel to push/pull instead of just pushing out. I'd take it apart and have a look. Might be as simple as cleaning it up and putting it back together with a fresh o-ring and crush washer.

I was hoping that was a good possibility. I'll check that out tomorrow. I'm glad I have a few extra o-rings and new washers around. 👍🏻

I'm hoping that it's not that drastic. I sure hope not, but that's a real possibility.