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Shut off while driving and will not start

Tiny
SWEETIE1965
  • MEMBER
  • 2004 GMC ENVOY
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 197,000 MILES
DTC P030, I tested and found out the coil pack was faulty. So, I changed in the parking lot of the parts store. I started it and it ran smoothly like it should. As I was leaving the parts store, I backed up then the engine just shut off and wouldn't start back up. I tested the fuel pump relay; I could hear nor feel a click in the relay when the key got turned on. Checked for voltage, the fuse box, one side of the relay gets a steady 12 volts, the other side gets nothing when the engine is cranking over. I cannot smell fuel at all when trying to start the engine. I checked the fuel pump fuse, it's still good. This has me puzzled because I usually can figure things out. In your opinion what could give me this problem?
It has been intermittent shutting off while idling but it would start back up. Until yesterday it shut off and won't start back up.
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Saturday, July 2nd, 2022 AT 11:32 AM

24 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

The fuel pump relay will have a constant 12v on the secondary side and 12v on the primary only when the key is first turned on for a couple of seconds. After it primes, the engine must start and there be an ignition signal for the PCM to continue running the pump.

Do me a favor. See if the engine starts for a couple of seconds using starting fluid. If it does and then stalls, we can confirm its fuel related. If there is no change, check to see if there is spark to the plugs. Here is a link that explains how that is done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Based on your description, it certainly could be either fuel or ignition related. However, the idea that it is stalling prior may indicate a faulty crankshaft position sensor. If you have a tachometer, take notice if the needle moves a little when cranking. If you have a live data scanner, see if there is an RPM signal. If there isn't, suspect the crankshaft position sensor has failed which will cause no spark to the plugs.

Let me know what you find.

Joe
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Saturday, July 2nd, 2022 AT 10:03 PM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
It does not even attempt to start. It just cranks over. As far as spark goes, I will check that first thing in the morning. It has been stalling for a couple weeks now but it would start right back up. I do not smell fuel at all getting anywhere. I will check for spark. If I don't have spark, I will probably change the ignition switch. I believe that is what the problem is.
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Sunday, July 3rd, 2022 AT 1:47 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
It does not have a tachometer. I think a faulty ignition switch is the culprit. It's not getting any fuel for sure. I will check for spark the first thing in the morning and let you know what I find out. It never gave me any DTC's other than P0301. So I checked it to find the #1 coilpack was faulty so I changed it. That's when this problem happened.
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Sunday, July 3rd, 2022 AT 2:05 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
I checked for spark. I have none so I know the ignition switch is the problem.
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Sunday, July 3rd, 2022 AT 8:51 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
The engine will not even crank over anymore. All the starter does is click. I know the starter is good. It was cranking over earlier this morning. Now it does just a click. One click, and that's all. No kind of constant click like a loose battery connection or something like that.
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Sunday, July 3rd, 2022 AT 8:53 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
I changed the ignition switch and it's cranking over but no start.
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Sunday, July 3rd, 2022 AT 10:19 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
You won't believe what the problem was. I thought about checking the PCM fuse which is a 15 Amp fuse. Well, it was blown. I changed the fuse and now everything is back to normal.
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Sunday, July 3rd, 2022 AT 11:02 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Wow, anything to make things confusing. LOL, I'm really glad you checked the fuse. It was difficult with only a cylinder 1 misfire to consider the PCM fuse failed. Regardless, you found it, and great job!

Thank you for the update and please feel free to come back anytime in the future. You are always welcome.

Take care and Happy 4th of July,

Joe
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Sunday, July 3rd, 2022 AT 8:29 PM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
Something keeps blowing the fuse for the PCM. I checked the wires on the pigtail for the number 1 coil pack. One of the wires broke. Do you think I can put a butt connector on this?
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Monday, July 4th, 2022 AT 9:01 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
I tried putting a pig tail connector on the number 1 coil pack. I'm not quite sure if I put the wires right. Something keeps blowing the fuse for the PCM. Everything was fine until I changed the coil pack for the number 1 cylinder. What would happen if the wires got crossed? Would it fry the PCM, or would it just blow the fuse?
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Monday, July 4th, 2022 AT 3:01 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

If you crossed the wiring, there would be power to the PCM at all times from the circuit. It shouldn't damage the PCM, but it could cause the fuse to fail.

How quickly does the fuse fail? If you carefully separate the wiring at the connector for the coil pack so nothing can short, does the fuse still fail?

Let me know.

Joe
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Monday, July 4th, 2022 AT 10:21 PM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
The engine starts and runs for a couple seconds then shuts off due to the burnt fuse. When I put the pig tail on, I also taped it up pretty good with black electrical tape.
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Tuesday, July 5th, 2022 AT 4:51 AM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
I found the problem. The new coil pack I put in on Friday is defective. I unplugged the coil pack then started the engine. It ran without blowing the fuse. When the old coil pack is plugged in, it runs with a misfire (PO301). That's why I changed the coil pack to start off with. When the new coil pack is plugged That's when the PCM fuse blows so it's a defective coil pack.
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Tuesday, July 5th, 2022 AT 9:20 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

That will certainly cause an issue. Have you replaced it already and is it running properly now?

Let me know.

Joe
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Tuesday, July 5th, 2022 AT 8:37 PM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
I replaced the defective coil pack. It runs fine now. No DTC's.
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Wednesday, July 6th, 2022 AT 4:43 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Thank you for the update. I can't believe how many faulty new parts I've been getting lately. It can be frustrating.

Regardless, I'm glad it's running good again. Please feel free to come back anytime in the future.

Take care,

Joe
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Wednesday, July 6th, 2022 AT 8:52 PM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
I just purchased a 1997 Ford Explorer with a 4.0. The engine runs great, but it has a few minor issues. There are two issues that concern me most. The first one is the instrument cluster. None of the gauges work properly except the gas gauge. The speedometer stays stuck on 30mph while parked. While driving it goes up and down according to speed, but when parked it's stuck at 30MPH. Second thing when I turn on the left turn signal the outside signals work after I changed the bulbs, there is a buzzing noise coming from the instrument cluster. And which fuse runs the third (high mount) brake light?
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Thursday, July 14th, 2022 AT 3:12 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

I have to ask a favor. I would be happy to help with this, but I need you to start a new thread. We try to keep the threads specific to one topic so it's more helpful to others.

Here is the link to start a new one:

https://www.2carpros.com/questions/new

I hope you understand. I will watch for your post.

Take care,

Joe
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Thursday, July 14th, 2022 AT 7:05 PM
Tiny
SWEETIE1965
  • MEMBER
  • 158 POSTS
My 2004 GMC Envoy has no evidence at all of any type of leak. I checked the oil in it like I usually do on a regular basis the other day. Well, there was not a drop of oil in it. It doesn't smoke at all, there is no wet spots on the belly pan. The oil plug is tight. Like I said there is no evidence of any kind of oil leak. What do you think happened to the oil? I checked in the bell housing of the transmission thinking maybe the rear main seal leaks, but nothing is wet at all. I put some new oil in it then drove it about 50 miles since then no oil has leaked out. It's still full where it supposed to be.
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Saturday, July 16th, 2022 AT 4:33 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

If there is no smoke and no leaks, check if there is evidence of it getting into the engine coolant.

Joe
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Saturday, July 16th, 2022 AT 5:09 PM

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