2000 Astro fuel problems

I have tested my fuel pump @ ~59psi and it will hold >55 for more than 3 min. When I first put it under load it comes up to speed normally. When I try to go to passing gear it bogs down as if it is not getting enough gas. This gets progessively worse as I drive it, to the point that I have to gingerly apply the gas to even get it up to speed. Is the pump just weak or should I be looking else where?

I am new on here myself. Since you have pressure, I would suspect you might not have enough flow through your filters. You didn't mention checking or changing the filters, so that is my first thought. Also, did it occur to you to have the gauge connected while driving, if you can manage to do it, to see what your pressure is under the fuel draw of the engine. These complicated engine systems of today also allow new procedures to be used. Of course don't forget that a possible gasoline leak, by the fact that you are working with a pressurized fuel line, can be dangerous. If you do this, please be careful.

61 PSIG is the normal pressure / specification for minimum pressure, but I've seen them start and run at 58 PSIG. The poppet injectors require at least that pressure to operate.

You need to test pressure both standing and when under load (higher fuel delivery) to understand the actual pressure.

Clean filters are important, ans so are reliable electrical connections. More often than not, the power connector at the top of the tank is resistive due to overheating. The ground connection near the tank is also a problem point, especially on an older vehicle. To determine if this is a problem, monitor voltage directly at the tank top connector (it's tough to get in there with probes) with the pump running.

Don't bee too surprised if you discover this:

http://www.wwdsltd.com/files/PumpConnector.jpg

I have changed out the filter with no change. I will attempt to check the pressure while driving, the Haynes man. says that the press should drop about 5# when running, will it drop more than that while driving? I am presuming that the press should stay fairly high to maintain the engine running during all conditions?

Once the engine is running, 58 PSI might keep it there.

These fuel pressures can drive you nuts. We can't be sure that all gages give the same accurate reading either. With the industrial quality gage I have hooked up now, it reads 52 pounds and it runs fine, after you give it a prime in the air cleaner to get it started in the morning. It will continue to start after that. I took it for a short drive and kicked it down a bit to see if it would accelerate without stalling or quitting and it took right off. We still don't trust it. Its an Advance pump that has run for 2 plus years so we are going to put a new Delphi pump in when it gets here. I will have to drive it about 45 miles to Pittsburgh. We will have the use of a brother in laws lift there which should make a pump change much easier, and the Astro has to go back to Pittsburgh anyhow. I won't go during rush hour and I think I will make it, but I am taking my cell phone, and crossing my fingers. I think my Aschroft gage is accurate but when this is over I will check it against some more Aschrofts for the hell of it. From the experiences of others on here, it shouldn't even be running!, but it does. Oh yes, I will hook this Aschroft gage up for the Delphi pump also, (hoping that it starts without priming), and that should be interesting. I'll post the reading too. (I wouldn't bet on anything about these pumps.)

We put a new Delphi pump in my 2001 Astro project. This morning with the old pump, to review, before starting it read 52 psi. I primed it and got it running, and it ran at 52 psi. I drove it 50 miles to Pittsburgh and it ran fine with no problems. Needing to prime it is not a situation you can have faith in. Our mechanic friend says when he has to prime one of these 4.3L Chev V6s, he knows its the pump, as I learned on this forum.

We installed a new Delphi pump this time. The electrical connector on top of the pump is different and they supply a new plug. You need to cut off the old plug and splice the wires with crimp connectors. (I am not crazy about crimp connectors for something like this so I used sealant on the ends of the crimp couplers to keep out the weather.)

The engine fired right up with no priming. Shut it off and hooked up the gage. With the engine not running and turning on the ignition, the gage popped right up to 62psi and then almost as quick the gage dropped back to 58 psi. We shut it off and tried this several times and it repeated the same reading 62psi and then dropping back to 58psi. After starting engine the gage read a bit over 54psi and allowing for a bit of gage error, even with this industrial gage, that pretty much agrees with the Haynes manual which said 55psi. (Haynes is not 100% clear about running versus not running readings.)

Delphi said this pump has improvements, but who knows what they mean?
The 62psi dropping quickly to 58psi before you start the engine seemed different, but? Its fires right up and runs great now, so my brother is happy, and I think running better without the vibration is because of the new timing gears and chain. Declutch, I wanted to add these comments and my findings to your thread to help with your engine, and I tried to be as accurate and specific as possible. I hope my comments can be helpful, but more than one mechanic has told me they don't completely understand why you can prime some of these engines and they will run fine all day, until the next day of course.
Hope everyones comments help you, their comments helped me, and I thank them for that.