Stupid fuel accumulator question

[Ron]

David's comments reminded me that a stock TBI setup has a fuel pump check valve, a likely candidate.
(Most TBI relays run the pump ~4 seconds to prime.)

Since it has been working for 10+ years, I don't see how it is wired would be a problem all of a sudden. But if it is wired through the rpm relay, I'd sure test the output or try another one.

Pop the lid off of the air cleaner and see if it is getting fuel the first time you turn the key that day to kill 200 birds with one stone!

What kind of pump?

[David T]

Many TBI systems have a transfer pump in the fuel tank that makes a low pressure, enough to get the fuel out of the tank and up to the next pump which creates the high pressure to run the system. Even with a check valve, if the system sits long enough it will lose any residual pressure. The key is to have a pump that can bring the pressure up quickly so the motor can start very soon after you start cranking it over. The check valve is mainly so all of the fuel in the system doesn't drain back into the fuel tank. If it does then not only does the pump have to pressurize the system, it must fill it first. That takes a little longer. On most systems there is a pressure valve on the return to keep that from draining back to the tank too. In doing the engine swap all of these kind of little things are not always done right. And even if they were, something may have gone bad.
David Teitelbaum

[Ron]

Many TBI systems have a transfer pump in the fuel tank that makes a low pressure, enough to get the fuel out of the tank and up to the next pump which creates the high pressure to run the system. Even with a check valve, if the system sits long enough it will lose any residual pressure. The key is to have a pump that can bring the pressure up quickly so the motor can start very soon after you start cranking it over. The check valve is mainly so all of the fuel in the system doesn't drain back into the fuel tank. If it does then not only does the pump have to pressurize the system, it must fill it first. That takes a little longer. On most systems there is a pressure valve on the return to keep that from draining back to the tank too. In doing the engine swap all of these kind of little things are not always done right. And even if they were, something may have gone bad.
David Teitelbaum

I'm with you here.
I can't think of a 4.3 TBI that used 2 pumps off of the top of my head (several fords tho)...not saying there wasn't, but can't see why with ~10psi, to the injectors. And in this case...well, any case, 15 seconds is a looooooog time to wait on ~10psi, especially if it starts and runs ok for the rest of the day.
Agreed!, this being an engine swap there is no telling -- we're just grasping at straws w/o more info.