95 Astro CFMI Fuel Injection Problem?

03-05-2006, 03:44 PM
Thank you for reading this post. I hope you can help.

95 Astro
4.3 Litre CFMI W Engine
157K miles

Replaced parts (year replaced)

Coil (2005)
Spark plugs(2005)
Cap rotor (2005)
Wires (2005)
Fuel Pump, pulsator and wiring harness (all OEM parts from dealer) (2003)
Fuel filter (2006)
EGR (2006)
Wiring Harness behind battery with 4 fuseable link wires (one link was fried) (2006)


Runs rough
Does not always start although it has spark & fuel pressure
Unusual exhaust odor (I am currently running fuel injector cleaner additive in fuel tank)


Code 44


I purchased vehicle in 2001 with 94K miles. It has been a workhorse until now. About 6 months ago it slowly began to run rough. But it still got me to where I had to go. I switched out the plugs, wires, coil, cap & rotor. It ran no differently. The old plugs where in good shape except that they showed they were running hot. I do not know why. The new wires were arcing (visible at night) so replaced with better grade. They still arc somewhat & the coil also appears to arc to the mounting bracket that holds it down (visible at night). Recently the vehicle has been running worse, some days better than others. A few times I had to shift into neutral at a stop light and give it gas to keep from stalling. Then it quit on me on my ride home from work. Towed it home. It cranked fine but would not start. I found fried out fusible link behind battery. Replaced that harness with salvage yard part. It started and I thought all was fine except next day it progressivly ran worse then stalled. Would not start. Tried it later and it starts. Turn it off & sometimes it will start and sometimes it wont. It showed trouble code 32 (EGR). I replaced EGR even though old one looked good. It made no difference. Now it shows trouble code 44 (Lean exhaust). I checked vacuum lines & they seem ok. Have not replaced 02 sensor. The EGR was $120 and I did not want to keep replacing random parts. I checked & rechecked electrical connections on wiring harness I replaced behind battery and they are tight. I get spark even when it wont start. I pulled off coil wire from distributor and get a blue spark from wire when I crank engine. I pulled a plug wire off distributor and I get spark. I also have gas pressure even when it wont start. I replaced fuel pump in 2003. At that same time I found a short in the pulsator in the fuel tank and replaced that along with wiring harness leading out of tank to a connection. I just replaced fuel filter. I took fuel pressure readings:

Key on engine off-62 psi (for few seconds-then when pump stops whirling it drops to 24 psi).
At idle 54-55 psi.
Engine running-when I gun accelerator psi jumps to 64 ps- then drops down to 50 psi-then levels off at 54 psi.
When I turn off engine the pressure immediately drops to 28 psi and usually it continues to drop to 0 psi within 20 minutes (although a couple times recently it has held pressure overnight at 24 psi).

I just spent 3 hours reading prior posts on this website.
I am wondering if my fuel injection/spider needs replacing?
Or is the fuel pump pulsator shorting out again as it did in 2002?
Or the fuel pump failing?
Or could it simply be oxygen sensor?
Or ?????????????

CD Smalley
03-05-2006, 04:17 PM
Seeing that the fuel pressure drops off, it's time for a new fuel injection "spider".

It should hold quite a bit of FP. You should not see it start to drop off, especially that low that quick. Exhaust smell is probably from a stuck poppet that is leaking fuel off or the regulator itself might be bleeding the pressure out into the manifold. Check ebay for a new AC Delco spider. You should expect to pay around $250-$275 for a brand new AC Delco one.

03-05-2006, 05:05 PM
Thank you for your reply.

The manual states that fuel pump pressure should read:
Key ON, engine OFF...........Approximately 58 to 64 psi
Engine running (at idle)......Pressure should decrease by 3 to 10 psi

Is it normal for pressure to drop from 64 to 28 psi when the fuel pump stops whirling or should it be holding at the 64 psi? Also, is it normal for pressure to drop from 28 psi to 0 within 20 minutes or should it be holding at 28 for long period of time?
Can you tell me which reading indicates it is time for the spider.

The manual does not clarify this.

Also, I called Autozone for price and availability of Fuel Injector Spider and was told they have no listing for this part. Is there a technical name that they wouuld understand?

CD Smalley
03-05-2006, 09:34 PM
They should understand that name. Call a non-chain part store. They will know. It should hold 50psi overnight. The drop in PSI that you are seeing tells me that the regulator is shot or a poppet is leaking.

Here is what you need:

http://cgi.ebay.com/ebaymotors/92-95-New-GM-OEM-S10-Blazer-Sonoma-Spider-Fuel-Injector_W0QQitemZ8031962851QQcategoryZ33553QQrdZ1 QQcmdZViewItem

03-06-2006, 07:48 AM
My '94 did all the same as yours- fuel pressure would drop to near zero after about a minute- I pulled off my upper plenum- to see the spider assembly- then energized fuel pump- by turning on the ignition- and it squirted gas right into my face- the plastic line going to the spider had a hole in it- replaced that and all was fine- until a few months later- then I went through at least three spider assemblies in 2 yrs- until I found that the wire leading to the spider had a break inside the insulation- took forever to figure it out- there is no real test for spiders- I bet I had that upper plenum on and off a dozen times- finally rewired- made my own wiring harness- dealer wanted $87 just for the plastic plug on top of spider--- you can buy rebuilt spiders from the guys in Indianna- Linder injectors- just google search for linder technical services- should get them- they are experts in injection- I think they are around $200-250

just my thoughts.....I do have 320,000 on my van now....and pull a Stock Trailer...

03-06-2006, 09:33 PM
Had the same problem until i replaced the spider and it worked back in 2004

03-11-2006, 08:36 AM
Thank you for your replies. This forum has been very helpful.
I pulled off the plenum and was surprised to see there are black sooty deposits covering the entire surfaces. There also appears to be an light overall coating of oil, too. There are actually small deposits of oil-like substance that is puddling in some crevices. The puddling is about the same diameter as an eraser on end of a pencil.
Any clues why oil residue would be in the plenum?
Is this normal?
After I took off the plenum, I energized the fuel pump by turning on the ignition key. The fuel pressure still jumps to 64 psi and when the pump stops energizing it immediatly drops to 22 psi. I do not see any evidence of leaking fuel. Should I still assume that the spider needs to be replaced?

CD Smalley
03-12-2006, 05:05 PM

03-12-2006, 08:08 PM
i just went through the same thing with my 95. autozone does have the part and you can get the number off the website i had to cross refference it with the part number i got off a random "gm" website that i got off a websearch. i searched around and there really are no discounts on that part out there so i figured id get on from my local autozone...i had to get the plenum gasket from a local parts store. the people at autozone are pretty much useless but the prices are pretty reasonable...they should have the part in stock. its easy to change just pay very close attention to what hoses go to what port it can be an "optical illusion" and also make sure the poppets are fully pushed in. pressurize it and check it for leaks before replacing the manifold. good luck..hope this helps

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