Truck stalls while driving?

1997 CHEVROLET 1500
210,000 MILES • 5.0L • V8 • 2WD • AUTOMATIC
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FREDERICK-59
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I have a 1997 Chevy Silverado C1500 with around 210,000 miles and automatic transmission.

This is kind of a long story, so I am trying to explain it as best possible without being too long.

For quite a while I've had this problem of a hard start where I'd crank it and it would seem to crank normally but wouldn't start. After cranking it another one or two additional times it would start and once it started there were no problems. Although sometimes even when it did start it would vibrate for a few seconds before it smoothed out the idle.

Then, and this is the biggest problem., last September I was using it and it totally shut off while driving. It made a sound that is hard to explain that was loud enough that I thought something physically broke, and I was looking underneath it but didn't 't see anything.

I had it taken to a garage who said that there was no spark coming out of the coil and they recommended changing the distributor, which they did.

When I got it back at first it was working but after a short time, like less than 30 miles, it shut off while driving again. I complained to them, and they ended up changing the distributor again saying it possibly was defective.

It seemed to work after they changed the distributor the second time although it still was starting and after a second shutting off but once started it didn't shut off while driving.

I changed the ignition coil and after that got a code that I don't remember what the number was, but it showed Ignition Coil High Voltage.
There is a mechanic who has been trying to diagnose it, but he says he needs it to stall and not start again but it always starts again.

I wouldn't be surprised if it had more than one problem. For one thing he says the fuel pressure is low. Sometimes when on for quite a while it goes down to 40-45 PSI and it's supposed to be 60-66 PSI. But he has got it to stall out by leaving it on for fairly long periods of time but when it stalls it stalls out fast and he doesn't think that would happen from low fuel pressure. He says if it was stalling because of the fuel pressure it would stall more like when you run out of gas; not like if you just turned the key off.

That's the most of it without making it too long. If you want to know anything else, please feel free to ask.
Apr 30, 2024 at 3:45 PM
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JACOBANDNICKOLAS
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Hi,

Without the code, it makes it a little more difficult for me. However, I have to ask. Has anyone checked the crankshaft position sensor? When they start to fail, heat adversely affects them causing a loss of spark to the plugs. As a result, the engine shuts down.

Once it shuts does, it can restart when the sensor cools a bit or simply makes contact again internally.

Do me a favor. Take a look through this link and let me know if it seems to mirror what you experience. Note: The sensor can fail and not set a code as well.

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Let me know. Also, if you could have the computer scanned again and let me know the code or codes found, it should help me. Most parts stores will do it free of charge.

Let me know.

Joe
Apr 30, 2024 at 7:14 PM
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STRAILER
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Here is the location of the sensor so you can check it out. Check out the images (below). Let us know how it goes.
Apr 30, 2024 at 7:36 PM
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FREDERICK-59
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Hello. Thanks for responding. The code is a P1351. Every time the truck starts but shuts off right away it sets that code. I started seeing that code after changing the ignition coil. But I get the feeling it doesn't have anything to do with the coil.

I read that article and yes, it definitely seems to sound like what is happening. Especially what it says about it doing it when it is hot and not cold.

The crankshaft sensor was replaced about 8 years ago. I'm not sure how long they last and I'm not sure what brand was used.
Apr 30, 2024 at 9:32 PM
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The P1351 code for a 1997 Chevrolet 1500 typically refers to an issue with the Ignition Control Module (ICM) circuit. Yep, this is where I would start, these sensors go out. Please let us know what happens.
May 1, 2024 at 8:58 AM
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FREDERICK-59
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Actually, I have it with a mechanic now but I'm starting to think he isn't going to figure it out. He did let it idle a lot to see if it would stall out and one day it did at least 4 to 5 times. But the problem is at least for him, it always starts right up again. Would it do that if it was the crankshaft sensor?

He did notice that the fuel pressure drops when it is running for a good amount of time, like an hour or so. He saw it go down to 40-45 PSI, but he doesn't think that is what is causing it to shut off rapidly like it does? He says if it was the fuel pump, which he says could be an additional problem, but it would shut off more slowly like when you are running out of gas.

Is there a way to check the crankshaft sensor to know if that is the problem for sure?
May 1, 2024 at 12:59 PM
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JACOBANDNICKOLAS
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Hi,

I have to agree with him as far as the fuel pressure is concerned, but anything is possible. As far as the crankshaft position sensor, I would try replacing it. Can it be checked? Yes, but it sounds so intermittent, it may test good. It's only a theory, but in my mind, it makes sense.

Note that the sensor isn't difficult to replace. I attached the directions below for you if you would like to do it yourself.

Let me know.

Joe

See pics below.
May 1, 2024 at 7:53 PM
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FREDERICK-59
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Will do. Thanks
May 3, 2024 at 10:10 AM
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FREDERICK-59
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HI, I haven't changed it yet, but I should this week. I am wondering if it is necessary to remove the negative battery cable before doing it like they say? Also, some people say after doing that you have to do a crankshaft relearn procedure. Is that true?
May 13, 2024 at 10:32 AM
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Yes, you can disconnect the battery to be safe, also you should to have to do a sensor relearn on it, it does not say instructions that you will need to.
May 14, 2024 at 9:29 AM
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FREDERICK-59
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I did install the crankshaft sensor today so we'll see how it goes and I"ll let you know. I have a question. As I mentioned above, the fuel pressure is supposed to be around 60-66 PSIi and the mechanic who had it showed me how when running for a while idling it goes down to 40-45 PSI.. Do you think that is low enough to cause it to stall out while driving? I know sometimes I have let it get very low on gas which I know is not good but I'm just wondering if that 20PSI of lower pressure would cause it to stall out.
May 21, 2024 at 1:53 PM
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JACOBANDNICKOLAS
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Hi,

Anything is possible. I think you would notice that pressure loss when the engine is under a load. For example, if you are climbing a hill, you would notice an issue. Could it stall? Absolutely, it could stall. We don't know for sure if it is getting lower when the vehicle is being operated. The only thing for sure is it drops at idle when the smallest amount of fuel is needed.

What I would suggest is to connect a fuel pressure gauge to the engine and run it out from under the hood near the wipers. Do it safely so nothing is damaged. Then, while driving, see if that pressure drops off more right before it stalls.

Here is a link you may find helpful for testing pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know.

Joe
May 21, 2024 at 6:50 PM
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FREDERICK-59
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Hi. Just wanted to give an update. To be honest I haven't been able to drive the truck since putting the crankshaft sensor. This is the first day I'm driving it because when I put the sensor, the next day I tried changing the fuel filter thinking that may help if the fuel pressure is low. Unfortunately that line was so rusty and the nuts didn't want to loosen no matter how much wd-40 I used the fuel line ending up leaking. So I took it to a garage and they fixed the fuel leak. Then they call me and tell me they are kind of worried about the brakes. They say the brake pedal goes pretty much to the floor. Believe it or not I am almost sure when AAA towed it from my house I believe they put the chain on the axel and broke the fu3l line that runs along the axel. And when he changed that line it started to spring leaks along the line that goes from the front to the rear while bleeding it.Anyway I just got it back. It seems to start better at least it hasn't did the thing where it starts and then a second later shuts off and thank God it hasn't shut off while driving but like I was saying I just started driving again. So I'll keep you guys posted. I appreciate your help.
Jun 1, 2024 at 9:10 AM
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Hopefully we got it fixed, thanks for getting back to us, please let us know what happens
Jun 1, 2024 at 10:52 AM
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FREDERICK-59
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Thanks. Will do. I have a question in the meantime. I read on the alldatadiy website for this truck that vehicles with a pressure under 44psi at idle.are considered undrivable So it makes you wonder how it even runs. One thing I noticed is that it doesn't seem to have as power as before especially if going up a steep hill. It was changed 7 or 8 years ago supposedly with a Delphi pump. But just the pump. Not the whole sending unit. Do you think the pump should be changed. Or should I just see how it goes for a while?
Jun 1, 2024 at 12:16 PM
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JACOBANDNICKOLAS
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Hi,

The idea that you lose power under a load is likely the result of low fuel pressure. At this point, I feel it may be in your best interest to replace the pump.

I sent directions for replacing the pump below. However, the tank will need to be removed to access it. For those directions, I would to know if the vehicle is a regular cab, extended cab, or is a cab and chassis (which I doubt).

Let me know what I can do to help.

Take care,

joe

See pics below.
Jun 1, 2024 at 9:22 PM
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FREDERICK-59
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Hi, I appreciate your help.

I think it is just the regular cab. I mean there is the area where you and a passenger can sit and there are no more seats in back and the 8 ft bed behind that area where the driver and passenger sit.

What worries me is if in taking down the tank if that would cause any more fuel lines to break. The pump was replaced about 7 years ago.

How high does the truck have to be to get the tank down? Can you do it if you put the front on ramps and jack up the back to about the same height?

Thanks again
Jun 2, 2024 at 12:38 PM
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JACOBANDNICKOLAS
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Hi,

Yes, if you aren't careful, it can damage fuel lines. As far as the vehicle height, you don't have to lift it. You will want it low so you can slowly lower it from the vehicle using a jack. The less fuel in the take, the easier the job. I would recommend disconnecting the battery before working on it.

Also, if there is room behind the driver's seat, it sounds like an extended cab. I attached directions below for removing and installing the tank. The directions start with pictures of each step and then are followed by the directions.

Let me know if this helps.

Take care,

Joe

See pics below.
Jun 2, 2024 at 8:46 PM
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FREDERICK-59
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Hello, just giving an update. A guy I know and I installed a new fuel pump with sender unit Sunday.

It seems to run a lot better since installing the crankshaft sensor and now the pump. Haven driven it a lot yet but ai did drive at least 15-200 miles since the pump and no problems.

I think it actually need both the sensor and the pump. The sensor seems to have fixed the hard starting and where it would start but after about a second would stall out. After the sensor it didn't seem to do that anymore.

But, I was working one day about 20 miles from where I live and it did start to stumble like when you are about to run out of gas which I attributed to the fuel pump. But it seems to be good now so far.

One thing that did happen though is that when I stopped in a parking lot and was about to shut it off the fuel gauge started to go crazy up and down and then stopped completely at way past the full mark.

I read something about taking both battery cables off and reconnecting them which I did. When I started it again it was the same but after a few seconds started working more normally at least like it was which still doesn't seem exactly normal because it floats around quite a bit like it did before changing the fuel pump. You would think with a new sending unit it wouldn't no? Could it be the instrument panel?

One other question: It says in the manual to tighten the tank straps to 33 foot pounds. It doesn't seem like I can because It seems pretty tight already and according to the torque wrench it isn't even at 25 foot pounds. Unless the wrench is bad. I'm afraid if I tighten it too much it will damage the tank or the straps will break somewhere.

What do you recommend?

I really appreciate all the help!
Jun 25, 2024 at 8:49 AM
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JACOBANDNICKOLAS
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Hi,

As far as torque, if the wrench is good, 33 ft/lbs really isn't overly tight. It won't hurt the tank or damage the straps.

The idea that the fuel gauge is moving around sounds more like an electrical issue. When you replaced the pump assembly, were the connectors in good condition? Was there any concern regarding the wiring?

Let me know.

Joe
Jun 25, 2024 at 7:53 PM
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FREDERICK-59
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Thanks for responding. I really didn't see anything that looked bad with the wiring. The only thing I noticed was the ground wire or whatever that is on the filler neck was broken off. But as far as the wiring going to the pump, I didn't really see anything noticeable that looked bad.

Thanks again.
Fred
Jun 26, 2024 at 7:56 AM
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FREDERICK-59
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One other thing, strangely enough the oil pressure gauge floats a little too although not as much as the fuel gauge but just a little more than normal. I mean normal for me is that it isn't moving barely at all. Anyway, just thought I would mention that too.

Thanks
Jun 26, 2024 at 1:28 PM
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JACOBANDNICKOLAS
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Hi,

The lower the RPMs, the lower the oil pressure and opposite. When you see it moving, do you notice if it is related to engine speed or does it move while the engine speed is constant?

Let me know.

Joe
Jun 26, 2024 at 8:51 PM
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FREDERICK-59
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No, sometimes it will be normal at idle in park for example or drive, and for no apparent reason it will start moving around a little. Not as much as the fuel level gauge but still somewhat abnormally.

Fred
Jun 27, 2024 at 9:11 AM
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JACOBANDNICKOLAS
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Hi,

As long as it doesn't drop too low. The sensor may be starting to fail or even a resistance issue in the connector or wiring.

Joe
Jun 29, 2024 at 7:15 PM
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FREDERICK-59
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Hi, I don't know if you can still respond here but I have a question. Since putting in the crankshaft sensor and fuel pump the truck hasn't stalled and almost always starts great. I say almost because in the last 2 months or whatever it was since I changed the crankshaft sensor three times it did do one of the things it used to do meaning it didn't start on the first crank. But mostly it starts good.

But ai noticed something recently that ai don't understand. This truck I believe is the CSFI type as opposed to the SFI type. The CAFI is supposed to have a fuel pressure of 60-66 psi at all times from what ai have read even in Chevy's service manual.

When I first replaced the pump, I really didn't check the fuel pressure. But recently, after around a month and a half of changing the pump, I was curious about checking it.

I checked it yesterday with a gauge that I rented that seemed new. With key on, engine off, it immediately goes to about 60psi, but after 1-2 seconds slowly drops down to about 53PSI. This is key on, engine off.

When you start it, idling, it goes to about 50psi and stays there.

Isn't that still low? It's at least 10psi lower than they say it should be.

I don't understand why this truck no matter what you do the fuel pressure is never 60-66psi. It was at 44psi when it was stalling out, so I feel like it only has to drop another 6 pounds and I be in the same situation. Seems kind of ridiculous with a new Delphi pump and supposedly the filter is new also.

Anyway, I appreciate your help.
Fred
Aug 8, 2024 at 7:54 AM
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JACOBANDNICKOLAS
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Hi,

Yep, I'm still here. LOL As far as the fuel pressure, it should be what you said, 60-66 PSI. If it drops off, you could have an injector leaking or a pressure regulator leaking.

Do you ever notice any black or dark gray smoke from the exhaust?

Let me know.

Joe

See pic below.
Aug 8, 2024 at 9:11 PM
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FREDERICK-59
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Not really. I mean maybe once in a while you might see slight grayish smoke but usually not. I think I see that mostly when it is cold so I'm not even sure it's smoke.

It did go up to about 60psi when rhe keybwas on and engine off but thwn it goes down slowly to about 53psi. Then started it is at 50psi.

Is there any wáy to check fuel injectors on that wirhout removing upper manifold?

Thanks,
Fred
Aug 9, 2024 at 1:16 PM
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JACOBANDNICKOLAS
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Hi,

Grayish smoke can indicate a rich fuel mixture. Take a look at the pic below. Since the fuel pump is somewhat new, I would eliminate that (at this time) as the problem. When you checked pressure, did you have the vacuum hose to the fuel pressure regulator disconnected?

Joe

See pic below.
Aug 9, 2024 at 1:51 PM
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FREDERICK-59
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I have seen the fuel trims on a cheap scanner I have and it does show a little rich especially on bank 2. I think it's like - 2-3% on bank 1 and - 8-10% on bank 2. As far as the regulator I'm like 99% sure the he fuel pressure regulator on this truck is under the upper intake manifold with the injectors.

It is normal that when you start it it would go down more than where it is when the engine is off wirh key on? I think I read that it would go down about 5 PSI, but this is going down more.

Fred
Aug 9, 2024 at 3:17 PM
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FREDERICK-59
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One other thing I wanted to ask that I forgot to in the mess I sent. Is it very complicated to change the fuel injectors and regulator which I believe you can buy together in one piece?

This is the part but I think this is an upgraded part because the original ones look different a little.

https://www.amazon.com/Standard-Motor-Products-FJ504-Injector/dp/B000IYP6JI/ref=mp_s_a_1_4?crid=1BC56WXHI0RQE&dib=eyJ2IjoiMSJ9.4X8dY_8LDINQOeNvFPCbrZGM7xpPXyKWxLPzXD8VuzR01klZzckHtanx3Dtv1Wxw6b7Nzro6GNmx9FKeViFE-dCPWVuDDt0dBCavKt0XAOG1o6yk6nfrrrn3CImcx04ouYR4IVfdlMmwvkkEO-3phwfvWOsmJYTRXVzElMRMMzTlxOKdypx-u73wxIgPb1FX_l6leF0KZGidcIudKicrEg.7hjwopQY0Xz9R1iNRZNUiUNtLGKvqgtyGNTM2_JvlE8&dib_tag=se&keywords=fj504+spider+fuel+injector+assembly&qid=1723251010&sprefix=FJ504%2Caps%2C205&sr=8-4

You can see the regulator in the second picture.

Fred
Aug 9, 2024 at 5:55 PM
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JACOBANDNICKOLAS
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Fred,

Yes, it is normal for the pressure to drop a bit when it is running, but according to the specs, it should still be at 60 PSI.

As far as the regulator, yep you are correct. It's under the intake. They make nothing simple.

Joe
Aug 9, 2024 at 9:31 PM
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FREDERICK-59
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Hi Joe,

Yeah, I know what you mean.

I have another question. A lot of times I smell gas when I am around the truck. Sometimes I have small 2-3 gallon tanks in the bed with gas but I don't think it's that.

I checked underneath and I don't see anything leaking unless it is something on top of the tank that I can't see.

One thing we did notice when I was changing the tank with the friend of mine is that there is a metal hose that is connected to a rubber hose that is connected to the fuel filler neck and we noticed when putting gas in the tank again that that hose apparently leaks on top.

I read on a website that an evaporator system that is not working properly can cause low fuel pressure. Do you think that is possible?

This is the hose I am talking about.

https://www.classicindustries.com/product/all-years/chevrolet/c1500/parts/K94764.html?gad_source=1&gclid=Cj0KCQjwn9y1BhC2ARIsAG5IY-6ResTll3c9yz0W7O1uKLyAnYcUkVP5ySA3rwJLc0sB1pG0OWDBj5gaAvVPEALw_wcB&gclsrc=aw.ds

It's the thin metal hose that is about 10 inches long.

Is it possible to put those sealants on there that are resistant to fuel? I say that because you can't even get that anymore except on that site that I sent you, but you have to buy all of it for $80.00 or whatever?

Fred
Aug 10, 2024 at 8:22 AM
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JACOBANDNICKOLAS
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Hi,

The smaller hose/tube on the filler is a vent for when you fill the tank. Yes, you could use something that is resistant to fuel, but make sure it is strong and doesn't block the tube. If it does, you will go nuts getting fuel into the tank.

Joe
Aug 10, 2024 at 6:29 PM