You may be able to locate the trouble by running the engine and tapping on suspected trouble spots with a screwdriver handle Jennifer. I suggest you start with the ignition-1 relay, ignition switch, and main wire connections.
Visual inspection plus disconnecting and reconnecting the cables. But no, we didn’t peel anything back. I will see if I know anyone who knows how to do that. Thanks for the info about that, oldschool.
It doesn’t buck and stall, Sean01. Does that change your idea about the torque converter? I know you’re right about the potential for it to be anywhere in the electrical system at this point, though. Thanks for the input.
I had a Chev that cut off randomly … no engine codes.
Turned out to be a failing ignition module.
OK, still many possibilities. I’m going to have to print this out and annotate it, I think.
It looks like I might be in the market for another indie mechanic who can check out all this stuff. The original one, the one who referred me to the dealership, says he’s “not a parts-changer,” which I think means he doesn’t want to spend money and time when he doesn’t know what the underlying problem is. But I’ve got to try something. Any thoughts on how to find the right shop? Google searching has not been fruitful so far.
To find a service shop in your area click on the ‘Car Talk Home’ at the top of the page and go to the lower right side of that page. Look for the Mechanics File and enter your info there.
Yep, those are the usual suspects. I think I’m going to have to phone a few more of them and see if they think they can try some of the things folks have mentioned. I know some of it I could do myself re: the battery connections, but I’m not sure I could get much further than that.
W.O.M. (Word Of Mouth) is still a good way to find a good mechanic/shop. You can, even, ask other mechanics for their recommendations. The question you want to ask is, “Do you know a mechanic/shop which is proficient in troubleshooting to find faults; rather than, one which changes parts until (“fingers crossed”) they find the fault?”.
We can’t troubleshoot from this board. All we can do is to try to limit the troubleshooting to a select number of parts or systems. It’s up to the mechanic to check and test those parts and systems.
OK, I’ll chime in. Somehow you have to determine if it is an electrical or a fuel problem. Once that’s done, you have halved the problem and can start eliminating possibilities. Personally I think it sounds like an intermittant fuel pump or connection problem to the fuel pump, or a fuel pressure regulator. Our Olds had a regulator problem and it would do the same thing. Fuel pump problems will give no codes though so if you are getting no trouble codes, that would lead me to fuel. Only way to test for fuel is to run around with a fuel pressure tester taped to the windshield and see what it says when it stalls.
For electrical, there is a device, which I cannot recall what it is called but the major shops have it. It plugs in and you drive around. When the problem develops, you push the button and it captures all of the sensor readings and so on for about the last 30 seconds. From that you could tell what happened to stall it out if it is an electrical issue.
If it does it often enough so you can get it to stall while the pressure tester is on it in the shop, and the diagnostic computer is on it, is the only other way except replacing parts to see what happens. But I don’t disagree with anything anyone else has said. Its just when there are no codes, I think fuel pumps and pressure which is not exactly GM’s strong point.
I would jumper the fuel pump directly to 12 volt battery terminal (through a temporary switch and fuse). If the engine still cut out with this set-up, I’d replace the ignition module with one from a wrecking yard.
Yeah, hellokit, this is a way better reponse than I expected. At least now I get a sense that there is quite a bit more troubleshooting that can be done, even with no codes.
Bing, I think the first mechanic ruled out fuel pump issues, but I can’t remember the reasoning behind it. Will look into the fuel pressure tester option, though.
If a fuel pump has an intermittent fault that can be near impossible to detect. About the only method of even making a halfway guess is by checking the current draw of the pump. A dragging pump will often have a higher than normal amperage pull.
Things like the battery cables and junction terminal should still be checked and cleaned. It’s amazing how often problems that are perceived to be major and expensive turn out to be something simple. Even auto techs, including myself, have a tendency sometimes to not see the forest for the trees.
It’s very difficult to keep telling yourself that it could be something ABC simple when thoughts of major headaches keep creeping into the mindset.
I’ve seen engines torn down because of bad plug wires, expensive engine work because of a faulty fuse, a transmission ripped apart because of a faulty U-joint, and cars that had a dozen parts replaced when the only problem was one lone, faulty spark plug.
The engine control computer, or module isn’t a bad guess. A bad computer might have no codes to give you. I have heard that some throttle position sensor problems won’t generate a code (don’t know).
If you bought the car with a salvage title, there’s no way to know if the computer is the original one or if they used the one from your car to fix another car. You never know.
"A dragging pump will often have a higher than normal amperage pull. "
Is that the what the fuel pressure tester detects?
A fuel pressure gauge shows how much fuel pressure there is in the fuel line and measures it in PSI. It may show some difference in pressure if the pump motor is dragging due to a mechanical problem. Using an ammeter to measure the pump motor current flow is what OK4450 was talking about, a different test. When a motor speed is forced to slow down the current flow in the motor windings goes higher.
I had the same thing. It turned out to be the mass airflow sensor. One way to test is for the intermittent fault is to tap on it with a screwdriver handle with the engine running. If the engine dies or stumbles that me be it. It is a somewhat pricey item, ~$75.00.
The old screwdriver handle trick. One of my all time favorites because it usually works so well on finding intermittent problems.
I would go right ahead and replace the Engine Management computer. It sounds like one of the circuit boards in there has an intermittent connection. Go over a bump and it hiccups, and wham! …Dies. This very same thing happened on one of my dad’s cars in the early '90’s…a 1989 Chevy Corsica. The new computer solved the issue instantly.
Read through more of the comments…rarely have I seen a fuel pump that does something like that. They either work, or the next moment they are dead…Dead…DEAD, never to work again. I’ve lived that experience a couple of times now. No amount of banging on the tank ever brought it back to life, so I’d rule that right out. I wonder if an auto salvage yard would let you somehow “rent” or “borrow” a computer, as long as you left other collateral? Try it for a few days and if the problem goes away, then buy it…