[AVC]

Prolonged crank is often just the in-tank check valve allowing system pressure to bleed off more quickly than normal, where the pump has to fill and repressurize the fuel line/rail. An annoyance, but not usually leading to sudden pump failure, in the vehicles I had experience with. For an around town vehicle, I'd leave it be until it got too annoying or the pump failed for other reasons.

For my main trip vehicle, I'd address it, as the pressure loss could be a splitting/leaking hose in or out of the tank, cracked pump housing, or a leaking injector, bad o-ring.... any of which would render a vacation miserable should they give up entirely.

A leaking injector will usually make the engine run rough for a few seconds after start.

 

[AVC]

Speaking of Seafoam....that stuff was designed to dissolve those sticky hydrocarbon deposits that 2 cycle engines are prone to. I've experimented with it on 4 cycle mowers and cars, and mostly it produced copious smoke, but little to no effect on the hard carbon and shellac deposits common to them. Seafoam probably dissolves sludge reasonably, given its ingredients, but I've never had an engine with that issue. B-12 on the other hand, is more potent on 4 cycle engines and hard deposits. Better still it seems, are high PEA content solvents.