I agree with replacing the filter first. The pump may be laboring due to the restriction.

The only thing that isn't clear is the quick bleed down of rail pressure when shutting down the
pump.

 

Ah Pur, I missed the 5PSI per second bleed down. Does it bleed all the way down to zero pressure? This would be indicative of a failed FPR... But again, if you were to isolate the pump, you could check to make sure that it wasn't a failed check valve or seal in the pump itself. It is easy enough with the proper adapters when you have the filter out.

 

I can't say how low the pressure will drop as I didn't allow it to settle long enough.
That's an easy test that can be performed again.

We may be dealing with multiple issues, so it's smart to get the filter changed and
redo the tests.

Thanks,
Tino

 

Okay..i'm not hearing that it's not okay to keep driving... but that the pump has the potential to go at any point still exists(i know that's true of any car but more likely in my case).

 

The fuel pump in any vehicle can just decide not to run at any point in time. That is the nature of the beast. It sucks I know, but hopefully it won't leave you stranded.

 

Yeah that's true.
What does the stock pump sound like...can you hear it in the cabin when you're not moving(i.e. no road noise)?

 

Some are loud, some are quiet. It really does vary. Sorry I cannot be more specific for you. The noise should be more of a high pitched whine than a growl though.

My old '01 Bonneville was quiet as a mouse until I had the fuel level sending unit replaced and from then on, I could hear the pump whenever I was sitting at idle.

 

Craig, it's fine to drive as long as you're not into hard acceleration.

The fuel pressure is sufficient for low load, in city and highway cruising. There is about 4-5%
of trim headroom to adjust so there is no extreme danger of running lean.

I sent you an e-mail about the filter. Let me know and we'll get that replaced ASAP.

 

No growl, it's a whine First time i heard it i thought i was hearing a train in the far distance on its' horn

Tino, i replied to you pm Let's get that fuel filter changed before the weekend.

Thanks guys!

 

I've been reading and searching the forum, as well as Google to learn more about the fuel
delivery, and engine itself.

From what I gather, this is a two piece manifold with a throttle body and air delivery on the
upper portion, and a common fuel distribution point, with injectors spraying into each runner
(on the lower intake portion).

I see there are two distinct fuel systems depending on the model year, so I 'd like to learn more
about the 1999 version.

Are there any photos available that show the injectors/spider assembly on the motor with the
top half of the manifold removed?