2003 Chevy Astro issues

Hey everyone, first post here. I’ve been dealing with several issues with my Astro but one lately has me concerned. I bought a code reader because the service engine light has been on. Some of the codes it threw were crankshaft position sensor, camshaft position sensor, random/multiple misfire, system too lean, ignition coil B Primary/Secondary malfunction, mass air flow sensor, and O2 sensor. I just changed the crankshaft position sensor, but didn’t redo the wiring. The code has come back, along with the camshaft sensor. All the other codes are gone for the time being. When driving down the road, every once in a while, the van, while having foot on accelerator, bucks fairly violently, and doesn’t seem to respond well to the attempt to accelerate. Usually in response to that I let off the accelerator, coast for a little while, and try again. Eventually it stops acting up and goes back to normal but usually not for long. Sometimes it seems to snap out of it completely, and then other times it’s pretty persistent. The van definitely has a rough idle from time to time, to the point where it will die on me. Sometimes after reversing, sometimes after sitting for a while. I’m wondering if possibly fuel injectors might need to be cleaned or even replaced. The van is nearing 300,000 miles with mostly original parts because it wasn’t taken care of too well by the former owners. I just changed the alternator and battery in it. I’ve done a small tune up on it as well. New cap and rotor, new spark plugs and wires, new fuel filter, new air filter, new PCV valve, and I had to put an oil sending unit on it as well. Any guesses what might be going on? I’ve also considered that maybe it’s a timing issue and that it needs a timing kit? I’ve always heard though that typically timing chain issues just get worse and worse, not back and forth, which is what this is doing. Hopefully the people here can give me a few options to get to the bottom of this. Thanks!

Once you cleared the codes… what codes come back? Please post the actual code… Pxxxx and we will try and help.

My old Chevy Astro would do this until I replaced the fuel pump.I cut an access hole in the floor board just above the fuel pump to replace it.I did not drop the tank because it was a pain in the neck.

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I did the same to my Avalanche. Makes the change a snap.

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Right now it isn’t showing any codes. The codes kinda come and go. Usually it’s the O2 sensor, crankshaft sensor, and camshaft position sensor codes. P0335 is the one for the crankshaft, and P0341 is the one for the camshaft. When they pop back up I’ll take note of it and post them on here.

Just checked it again and they are back. P0335 Crankshaft Position Sensor A Circuit and P0341 Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor. Definitely weighing a few things here to see if I can get to the bottom of this. I really don’t want to lose this van. I love this Chevy Astro.



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The acceleration problems with bucking and jumping are almost certain to be the result of failing fuel pressure and because it is intermittent the fuel pump is the most likely cause so I go for replacing the pump.

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Would it be good to check the fuel injectors as well? As far as the cam and crank, maybe timing or would all of that likely be because of an intermittent fuel pump?

Well I didn’t want to post another question, and was hoping that last one would be answered, but I guess I’ll just replace the fuel pump and then go from there. If it doesn’t fix it I’ll just go ahead and post that with my question. Thankfully, I already have a brand new fuel housing assembly and fuel pump in box waiting to be put in. I’ll post the results of that. I’ll get around to that on Saturday, more than likely. Thanks again.

Don’t forget to cut an access hole in the floorboard above the fuel pump to take it out. Use some sheet metal screws to fasten the new metal piece. Get some roofing ciment to close the gap between your new piece and the access hole.

If you think it will be tough to remove the seats and carpet to cut a hole in the floor just let the thought pass. Without a lift and a transmission jack removing the fuel tank is a real PITA and dangerous.

This van does have CSFI . . . keep that in the back of your mind, if the fuel pump doesn’t solve all the problems

It wouldn’t be tough to do that at all. The issue I’m more concerned about is that the Astro has a unibody. I have heard that cutting an access like that, even though some have done it, can lead to stress cracks, or compromised frame. I’m not entirely sure really. Other than that, my main concern was sealing it back up in a professional manner.

Yes. So with that being said, if the fuel pump doesn’t in fact fix the problem I could have a clogged or faulty fuel injector(s)? One of the codes the van was giving for a while was random/multiple misfire so I was kinda thinking that might possibly be a problem but of course, not sure.

speaking from experience . . . those P0300 random misfire codes are somewhat misleading

A smart guy who looks at live data and mode 6 data will soon determine it’s very often not random at all. he’ll be able to determine exactly which cylinder is the problem

If I were you, I’d find out exactly which cylinder is the problem before doing a fuel pump

On the other hand, a bad crankshaft position sensor or fuel pump would affect all cylinders

I’m very familiar with replacing fuel pumps on Astros, and there are a few opportunities to mess up, and you will be absolutely hating yourself, when you have to do the job again, or even worse, have problems that didn’t exist before. I won’t get too specific, but don’t fix what isn’t broke.

To sum it up . . . more testing is needed

Determine if the problem is affecting all cylinders . . . or just specific cylinders

Plan your repairs according to your finding(s)

'nuf said

I’ve never cut the floor to deal with a fuel pump myself @botard89 but I have seen well done jobs making such repairs and when you consider the center of the floor only bears the load that would be laying on it such repairs don’t weaken the uni-body structure.

But I do agree that ‘professionally,’ your situation would require some serious testing. I often “shoot from the hip” to suit the situation as I see it and “from the hip.” considering the time and cost of test equipment and the likelihood that the pump is the problem and if you have a drill and a get a pack of cutting discs you might somewhat quickly get back on the road.

But as always opinions vary.

I can’t remember if I said this or not but I did swap out the crankshaft position sensor and still would like to swap the camshaft position sensor as well. Unfortunately, it didn’t fix the problem. The van seemed to run a little better for a little while, but afterwards it went right back to the same thing. I’ve noticed along with getting the speed up to around 50-60+ and it doing this, extended runs seem to bring it out as well. It’s almost like once it’s warmed up a good bit it wants to start with the jumping/skipping/bucking and basically I think that is a result of something in the fuel system acting up. I know the fuel gauge doesn’t work so at very least if I do put the entire fuel housing assembly in then hopefully it will give an accurate reading and if I’m lucky maybe the main problem will go away. I already have the part anyways so I don’t think it would be bad to go from there as well as get that camshaft sensor in too. If that doesn’t do it, I’d like to check the fuel injectors, but I’m not sure if those symptoms exactly line up with a faulty or clogged injector. We shall see though. I’ll try to look into performing some extra tests as well to better determine the issue at hand, and anything new I’ll try to remember to post here.

Also don’t rule out boiling gas in fuel lines. If lines are too close to a heat source, and you’re missing a heat shield these symptoms can happen.

What do you mean . . . ?

Your fuel pressure gauge . . . the tool . . . doesn’t work?

If so, then use another one

You need to use one of these kits with shut off knobs . . . so that you can determine if the pump is good and/or if there’s leakage from that point on, such as in the engine bay