intermittent stalling

[justoneman]

Hello I just bought a 2004 Astro cargo van. The previous owner spent the past year trying to solve a stalling issue. He informed me he had a shop trying to fix his van. They replaced all the basic sensors, the coil, Distributor cap and wires and plugs. They replaced the main engine control module. They replaced the fuel filter and the catalytic converter and oxygen sensors. None of this has fixed his intermittent stalling problem so he gave up. I bought the van and had it drive fine for a day and then stall on me. It does it at start up. It does it after a while of driving coming to a stop sign. It will do it rounding a corner slowly. It will be fine and the suddenly at speed run badly. I cleaned the throttle body and thought perhaps I had fixed the problem. Not so. I figured it might be a fuel delivery problem since he had not replaced the fuel pump. I ran a fuel pressure test. It is at 55+ pounds. It is that even when the engine stalls out. After shut off the pressure stays up. It is a shame because the engine sounds great when this problem does not rear its ugly head. It starts instantly with the first twist of the key. So I am ready to delve into each possible problem. Not sure where to start though. Any thoughts?

[Rod's Trucks]

That may very well be a very time consuming challenge, but I would first be looking at the ignition system.
The PO has obviously touched the simple bases. You get the knowledge that you have a lot of new parts, so you may have to consider more subtle things, like corroded connections or broken wires..
I cannot think of anything, other than the ignition system, that could make it cut out that randomly, while you still have fuel pressure.
Unfortunately the ignition system connects all parts of the engine control , and related wiring and sensors.

I would head to a JY and salvage any of the modules and sensors that have not already been replaced ( or even some that have been, for later use as spares). try swapping them in, one or two at a time. Visually check every connector and the related wires as best you can, looking for any cracked insulation ( a possible place where corrosion could get to the wire and eat into it)
If it is something that is intermittent It may get worse when wires are moved, or it may go away for a while.

I once had a customer with a nice older Volvo that would suddenly die at apparently random times (except when the mechanics would take it for a test drive...of course). It did not 'run out of gas' kind of die...It just stopped like the ignition was shut off. According to the customer, a tachometer I had temporarily hooked up would instantaneously go to zero.
She finally left it for me for a week while she was on vacation. We outfitted the ignition system with a couple of additional sensors and I agreed to drive it on a 200 mile trip that weekend. It finally died while I was driving it.
We learned the signal from the distributor to the electronic ignition was shutting off when the failure occurred,
We found ( along side a rural road) the wire harness from the distributor went down along the front of the engine and was retained in place by two or three small metal tabs. Under a small layer of old dirt and oil, one on the tabs was slightly loose, allowing the two wire harness to move slightly with the motion of the engine, and it had rubbed thru the protective sleeve and then the insulation on one wire.
It was shorting the ignition signal to the engine block occasionally.
It was an easy fix, once the problem was found.
The point being...nearly anything is possible when it comes to intermittent electrical issues. It is not always a specific component, module, or connector.
It may be a painful trip, but keep us informed as to what you are doing. I am sure others, with more experience, will chime in with suggestions and first hand experience with similar problems.
Rod J
Issaquah WA

[rorgeastro]

My 2000 Astro Cargo van stalled intermittently when I first got it.. Usually during turns. It turned out to be a loose side terminal battery bolt. The aftermarket battery had a recessed thread which allowed the short OEM bolt to cam out..it looked tight but wasn't.

[justoneman]

That may very well be a very time consuming challenge, but I would first be looking at the ignition system.
The PO has obviously touched the simple bases. You get the knowledge that you have a lot of new parts, so you may have to consider more subtle things, like corroded connections or broken wires..
I cannot think of anything, other than the ignition system, that could make it cut out that randomly, while you still have fuel pressure.
Unfortunately the ignition system connects all parts of the engine control , and related wiring and sensors.

I would head to a JY and salvage any of the modules and sensors that have not already been replaced ( or even some that have been, for later use as spares). try swapping them in, one or two at a time. Visually check every connector and the related wires as best you can, looking for any cracked insulation ( a possible place where corrosion could get to the wire and eat into it)
If it is something that is intermittent It may get worse when wires are moved, or it may go away for a while.

I once had a customer with a nice older Volvo that would suddenly die at apparently random times (except when the mechanics would take it for a test drive...of course). It did not 'run out of gas' kind of die...It just stopped like the ignition was shut off. According to the customer, a tachometer I had temporarily hooked up would instantaneously go to zero.
She finally left it for me for a week while she was on vacation. We outfitted the ignition system with a couple of additional sensors and I agreed to drive it on a 200 mile trip that weekend. It finally died while I was driving it.
We learned the signal from the distributor to the electronic ignition was shutting off when the failure occurred,
We found ( along side a rural road) the wire harness from the distributor went down along the front of the engine and was retained in place by two or three small metal tabs. Under a small layer of old dirt and oil, one on the tabs was slightly loose, allowing the two wire harness to move slightly with the motion of the engine, and it had rubbed thru the protective sleeve and then the insulation on one wire.
It was shorting the ignition signal to the engine block occasionally.
It was an easy fix, once the problem was found.
The point being...nearly anything is possible when it comes to intermittent electrical issues. It is not always a specific component, module, or connector.
It may be a painful trip, but keep us informed as to what you are doing. I am sure others, with more experience, will chime in with suggestions and first hand experience with similar problems.
Rod J
Issaquah WA

Thank you very much with your writing down such a great example of what I might be encountering. It is a great story of the difficulty of tracking down such an electrical problem. It sure does seem like it is likely as you say a shorting out situation. My van does not peter out like a starve for fuel. It is more like shutting down. I will take your advice as a jumping off point and go buy a little mirror on a swivel and a flashlight on one too, so I can get a good look around every nook and cranny. Thank you again.

[justoneman]

My 2000 Astro Cargo van stalled intermittently when I first got it.. Usually during turns. It turned out to be a loose side terminal battery bolt. The aftermarket battery had a recessed thread which allowed the short OEM bolt to cam out..it looked tight but wasn't.

Thanks I will check it out as I did notice some stalling on left hand turns. I will just have to go through every little section of all the wiring. At least there is some good weather in my areas forecast. Good laying on my back in the driveway weather.

[Leeann_93]

55 psi isn’t enough. Needs to be over 58 and, better, over 60 psi.

[justoneman]

55 psi isn’t enough. Needs to be over 58 and, better, over 60 psi.

When I prime the pump it is at 60 psi and then drops down to 56 and holds that after shutting off the engine. I read that 55 was desirable?

[WildBorego]

Hello I just bought a 2004 Astro cargo van. The previous owner spent the past year trying to solve a stalling issue. He informed me he had a shop trying to fix his van. They replaced all the basic sensors, the coil, Distributor cap and wires and plugs. They replaced the main engine control module. They replaced the fuel filter and the catalytic converter and oxygen sensors. None of this has fixed his intermittent stalling problem so he gave up. I bought the van and had it drive fine for a day and then stall on me. It does it at start up. It does it after a while of driving coming to a stop sign. It will do it rounding a corner slowly. It will be fine and the suddenly at speed run badly. I cleaned the throttle body and thought perhaps I had fixed the problem. Not so. I figured it might be a fuel delivery problem since he had not replaced the fuel pump. I ran a fuel pressure test. It is at 55+ pounds. It is that even when the engine stalls out. After shut off the pressure stays up. It is a shame because the engine sounds great when this problem does not rear its ugly head. It starts instantly with the first twist of the key. So I am ready to delve into each possible problem. Not sure where to start though. Any thoughts?

Sounds like a leaking fuel pressure regulator

[justoneman]

If that was the case would I not see low pressure at the schrader valve? I guess the fuel pressure regulator is after the schrader valve right? Also the van runs fine for days then suddenly shuts down rather than running like it is starved for fuel when it does.

[justoneman]

So I suspect I have an electrical issue but in the interest of eliminating fuel issues I have to ask this question to all: Does the fuel pump need to kick out 60 psi for the engine to operate and if I had a leak in the fuel pressure regulator would I not see bleed off with a pressure test?

[02LS1]

My 95 has been doing it for months. Turns out that there is a carbon spot somewhere in the cylinder head or on the top of a piston which causes misfiring and it will misfire enough that it will stall out. Using an induction cleaner has worked a couple of times to clear up the problem But, it does return.. Although, I think with Low octane/ethanol gas, the problem returns. Sometimes just using premium fuel in it makes it run extremely well but not perfect.

[WildBorego]

So I suspect I have an electrical issue but in the interest of eliminating fuel issues I have to ask this question to all: Does the fuel pump need to kick out 60 psi for the engine to operate and if I had a leak in the fuel pressure regulator would I not see bleed off with a pressure test?

exactly 60 psi?? No the van will run on less, Like crap but it will run.
Check you oil dipstick you might start smelling gas in the oil. A leaking regulator will cause fuel to leak into the engine.

[justoneman]

I have the Haynes Astro repair manual. It states the specs of the required fuel pressure for the CSFI system. This is what I have in my 2004 right? Then:

Key on engine off: aprox 55 to 61 psi.

Engine on at idle: psi should decrease by 3 to 10 psi

Sounds like my 60 psi at priming and 56 psi engine running at idle is entirely within specs

[Leeann_93]

No. You have MFI, which is 2002 and up.

[justoneman]

No. You have MFI, which is 2002 and up.

Nope CMFI is 1992 to 1995. Just read it in the Haynes.

[Leeann_93]

No. You have MFI, which is 2002 and up.

Nope CMFI is 1992 to 1995. Just read it in the Haynes.

It’s funny that you think that Haynes is the authority.

CPFI is 1992-1995
CSFI is 1996-2001
MFI is 2002-2005

[justoneman]

No. You have MFI, which is 2002 and up.

Nope CMFI is 1992 to 1995. Just read it in the Haynes.

It’s funny that you think that Haynes is the authority.

CPFI is 1992-1995
CSFI is 1996-2001
MFI is 2002-2005

So this Haynes repair manual is not good! Damn it! How do I get the real information then if I cannot trust the specs in a manual. I guess I can get them from you huh?

[Rod's Trucks]

Historically, Haynes has been pretty generic and not always accurate, with some changes.
I found many occurrences of erroneous information, specifically with wiring diagrams, on foreign car models.
There would often be one diagram ( very small and crammed onto one page) that was to be representative of several years of minor model changes and possible optional features.
Information in a Haynes manual is generally good, but you have to be careful with the small details.
Rod J

[AstroWill]

So this Haynes repair manual is not good! Damn it! How do I get the real information then if I cannot trust the specs in a manual. I guess I can get them from you huh?

GM Techline eSI + virtualbox = Digital Factory Service Manual

See the links in my signature.

[sixsix]

... CPFI is 1992-1995

CPFI is also known as CPI ( it is the OEM name )

Many aftermarket firms are calling it CPFI ( adding "Fuel" to the system name )

Here's Wiki:
1992 introduced a new version of the 4.3 L (262 cu in), the L35. This version of the 4.3 L (262 cu in) was equipped with CPI (Central Port Fuel Injection).
It even goes on to say... This system allowed for a Multi-Point Fuel Injection, using one injector.

CPFI is 1992-1995
CSFI is 1996-2001
MFI is 2002-2005

Interesting... and again by Wiki:
The Vans started using SCPI in 2002 ( L35 motors ), then MPFI in 2003 thru 2005 ( LU3 ).

But remember, some refer to MPFI as MFI, like GM in their own docs....
- but then in another doc from similar era/years printing... will say MPFI and MFI in the same paragraph.

There is some confusion over whether the P stands for Point or Port.
They mention both within the same set of instructions.
The MPFI system of 6 injecters is also avail. to upgrade the 2002 Van's SCPI system.

After reading several GM Docs, and several Wiki docs and members here, I have learned:

- The letters S, C F and M are sorta' used willy-nilly by all involved, especially GM.
- Have to watch out for some Vans having been upgraded by a previous owner.
- Can't always believe everything Wiki or GM says.