Astro 2001 collection of problems

My brother had a tune-up on this Astro and it didn't make a whole lot of difference to the rough running and vibration of the engine. The front seal was leaking at 130K miles, the water pump was slowly leaking at the weep holes and the front cover seemed to be leaking oil also. The engine started fine when warm, but the longer it sat, the harder it got to start and only started after priming in over the air cleaner. We decided to tear into the leaks, replace the front cover with a new seal, a new waterpump, and while I was in there a new timing gear set from Competition Cams. I also checked the balance shaft gears for wear and the timing marks were lined up as the manual stated. The timing gears, basically what I think is a single roller gear set by GM, was not as bad as we suspected. The service manual say when you have about 5/8" of slack, change them, they had around 1/2" to 9/16", but while I was in there they got changed. The engine was shaking a bit at idle, so I think the new timing gears and chain helped, its not shaking anymore.

All of this solved the leaks and the engine idles smoother. I had to prime it again for the first start. The service engine light was on before I started all of this but its off now and I didn't expect anything I did to shut off the check engine soon light. Pressing the gas to raise the rpm a bit over idle and there is a rough running range. I ntend to check into that, maybe plug wires are crossed, doubtful but? Needing to prime it after it sits is a "prime" concern. Could the coolant sensor be part of the problem? I havent had a scanner on this, but it was checked with no codes present before I got it. (I am going to buy a scanner.)
After it has been run a while, you can stop and start it any number of times. The fuel pressure was checked before I got it and the tech said it was OK, but I have a gage and intend to check it myself. A second post will cover a brake problem, this post was getting fairly long.

Now I think by reading the other posts on fuel pumps and the pressure regulator, I will get this starting problem solved. I have a truck and Its not this sensitive to fuel pressure for its Fuel Injection system. Its older and not a GM. Time to play catch-up to work on these newer ones. This is a great forum that can help everyone "play catch-up". I will tell my friends about it.

I hooked up a fuel pressure gage to this 2001 Astro. Turned the key on and the pressure was 55psi and according to what I read here, this is not enough. Tried to start it, it hadn't been run for 2 days because other things needed attention, and it cranked fast enough but wouldn't start. I gave it a very short spurt of Gumout carb and throttle body cleaner into the air cleaner and it started as quick as you could want. Running, the pressure was 55 psi still. I let it run for maybe 10 minutes and shut it off. I watched the gage to see if the pressure was going to drop but it slowly climbed to 63 psi. I let it sit for about a half an hour and it started right up again and the pressure went back to 55 psi. I let it run for a while and noticed the pressure was no longer steady but was fluctuating quickly from 52 to 58 psi, but the engine seemd to be running well enough. Then I shut it down for about 2 hours. Came back and the gage read 40 psi. Turned the ignition on and the gage went to 55 psi and the engine fired right up again. Can anyone decipher what is going on here?

Another thing is that I looked through the Haynes manual to figure out where the fuel pressure regulator is, it is inside the intake manifold, and there is steel supply and return lines. What has me curious about this is they show the fuel pressure regulator as having a vacuum port, like my truck does, but I can't find a vacuum line. The way the fuel pressure fluctuates made curious as to what my vacuum gage would show. Can anyone shed some light on this also?

I don't know about the newer FPRs for the injected engines, but my '93 CPI FPR does not have a vacuum port (at least, not that I remember...not one to hook up, anyway).

Your fuel pressure is low and your leakdown is a little high. I'd suspect your pump was starting to fail.

MT will chime in with the test to isolate whether it's the pump or the FPR when he sees this, however ;)

Thanks for the reply Leeann. I suspect the pump also. Its an Advance pump we put it almost two years ago and everyone tells me they only last 1 year. My brother wants to resist dropping that TANK again! I don't blame him and the Advance pump was over $300 as you might know and they don't look like the most impressive auto parts I ever saw. A lot depends on these pumps and even the OEM pump looked like junk to me.

I have another gage to check the first gage, but the fluctuating pressure I have seen on the first gage also has me concerned. I am still interested in hooking up a vacuum gage somewhere. It runs better now but it did vibrate at idle before. (I checked the balance shaft gears and their timing and they were ok.) The vibration is why I went after the timing chain and it was close to where they say to change it at 130K miles. The front cover and seal was leaking also and I am glad that greasy part or the project is done.

We no doubt are very likely to be dropping the tank again. (ugh)

Yeah, sorry about that. AC Delco/Delphi for the win, unfortunately, though none of them look particularly robust, as you said. I think you did pretty well to get 2 years out of it. Lots of guys find they're bad out of the box, even more find they're bad in a month or two.

I just did the tank drop dance a couple months ago. Not so fun by myself (especially since it was my first tank/pump), but doable. Would have been easier with any help. I even had beer!

Wow, just getting a month out of a new fuel pump is no fun. My brother remembers us paying $359.00 for this 2 year old pump and it looks like he needs a new one. It sure wasn't worth $359.00! I haved a Harbor freight gage I picked up on sale for $7.95 when I was walking around in their store. It was the first gage I used and it read 55psi. I got another gage from a mechanic, bought at an auto parts sore for fuel system service, yesterday it read 61psi. Now I also happen to have some new Aschroft gages, an american brand that makes high quality industrial gages. I replaced the Chinese gage on the Harbor Freight rubber schraeder test line with an Aschroft and it reads 52psi. I have more faith in this Aschroft gage's 52psi reading than the others, especially when we are dealing with something as particular as these GM 4.3 V6s, and this one doesn't want to start without priming. So you think AC Delco is the best pump? I was also wondering what NAPA has in the way of pumps? I use to deal at NAPA for a long time but the auto parts business has really changed, hasn't it? If there is a better pump you can depend on?, I hope someone will tell us.

Yes, AC Delco or Delphi for the pump - that's GMs OEM supplier.

Check rockauto.com and gmpartsdirect.com for prices on your pump - online will always be cheaper than in a brick and mortar store.

I don't deal with NAPA around here; they only have kid computer jockeys working at ours and they know nothing. I deal with a local jobber parts house.

I have bought a few things at Rockauto and I will check gmpartsdirect also, I forgot about that one. We have a couple of knowledgeable mechanics that work here at the local advance, and I have gotten some excellent parts there, but now I know about the pumps. By the way, we have Wyotech here, the automotive and Diesel mechanic school and the town is crawling with students. Some of the better ones have worked at our Advance, even a few girls. Girls have an advantage with their smaller hands, and cad/cam is allowing the design and building to much closer tolerances with no allowance for hands! Thanks Leeann.

Anytime ;)

Our Advance and Pep Boys are even worse than our NAPA. I only go in to get fluids...

I found and ordered a Delphi pump at autopartswarehouse.com for $214.95 with free shipping for this 2001 Astro. We will dropping the tank after all. By the way this plastic tank is 27 gallons, are they all that size?

As far as I know, the tanks are all 27 gallons.

I think that's what I paid for my Bravada's pump from Rock Auto. Not cheap, but better than $400...

This 2001 Astro has had a lot fixed on it now. This will be the second fuel pump and a few other things I mentioned on here. The fuel filters have been changed. It also had the transmission rebuilt by a good mechanic in my area, two and a half years ago, you take it out and give it him and he will do a first rate job on it. You can install one of his rebuilds and forget about it, it will work fine. So now I am changing the anti-freeze and will check the timing since someone else did the tune-up and who knows if he checked it or whatever when he worked on the dstributor. I might as well be completely thorough and finish all of these details once and for all. Now I looked at the Haynes manual and they give engine rebuilding info etc., but I don't see an explanation on setting the valves. I am old school, even with hydraulic valves, at some time after all of the miles we put on engines, it is still a good idea to adjust the valves to compensate for any wear. I don't hear these valves clacking but you can hear a faint clicking at idle. The Chev V8s I always have adjusted are "1 turn down from zero lash" and you do this running as you probably know, and it always worked well for me. Has anyone adjusted these 4.3L V6 valves and what method was given. I don't think I have seen it written, but I will also check further.

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Location: Blairsville, Pennsylvania
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Re: 2000 Astro fuel problems
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.



Join Date: Sep 2009
Location: Blairsville, Pennsylvania
Posts: 23
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Re: 2000 Astro fuel problems
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.

To finalize this thread, we put in the new Delphi fuel pump last sunday and the 2001 Astro has been running great since then. With the new pump, it started instantly without even giving it a second to refill the lines or whatever. I think we started it again just for the fun of it. Then we shut it down because I HAD TO SEE what the gage read with the new pump. With the rngine off and turning the ignition switch to on instantly gave a 62 psi reading and just as quick it dropped back and settled at 58 psi. We turned it off and on a few times to confirm this. After starting the running reading is 54+ psi. The gage needle is a bit passed 54 psi and actually could be 55 psi. The divisions on this industrial gage are 2 psi. 55 psi is what the Haynes manual said, but I don't remember what they say about running versus just turning the key to "ON"

The Delphi pump had a new electrical connector with it. I had to cut off and save the old connector, (who knows if it will be needed for another pump change??) and splice the vehicle pump wiring to the new connector.

The Delphi pump instructions said it is an improved design?, I hope that it is true and it lasts. The mechanic friend we know says that priming an engine like this is his test for checking the pumps when they don't start normally. If it starts with a prime and keep running, its the pump!

Thanks everyone for your help and input.