Jump to content

engine stumbling

willlgord

Recommended Posts

willlgord Enthusiast

willlgord

Posted
Posted

I have a 99 Yukon with the 5.7 engine. I've owned the truck about nine months, it had 78,000 miles on it when I got it (97,000 now). I noticed it would cut out then, but it would only do it for maybe half a second and it only happened three or four times during the whole nine months. It didn't seem to be a big problem but there was always the question in the back of my head what it was. Well, this past weekend we pulled a trailer on a 1000 mile trip and the problem has gotten much more serious. After a bout of stumbling it would clear up and run perfectly, I thought it might be dirty fuel injectors and put some injector cleaner in the tank but that didn't help. Now it's starting to do it to the point where I'm wondering if it's going to quit all together. When it starts doing it the service engine light might flash but not stay on. I took it in to get the codes read but since the light didn't stay on they said there was nothing to be read (I thought there may be stored codes). Lately when it has a stumbling episode the ABS light will come on and stay on until the truck is shut off and restarted. I've replaced the fuel filter, the cap and rotor so far and dumped in another can of injector cleaner. The engine always idles perfectly regardless of how it's been running. I think the fuel system might be part of the problem since it seems to happen more while the engine is under load, but it will give me trouble sometimes whille going down a hill too. If I give it full throttle when it's stumbling (trying to "clear it out") the engine will ping and there's a spitting sound under the hood. I'm wondering if an electrical problem is the cause since the ABS system is affected. I thought about the plug wires but we drove through a fair amount wet weather and it didn't make the problem any worse. Could it be the coil? Please help!! I have another long trip in a week and all my money has to go for gas, otherwise I'd already have it at a shop! Thanks... Bill

firstruck Enthusiast

firstruck

Posted
Posted

Sounds more electrical than mechanical. Have you had the battery checked? Could be shorting out causing spikes. Modern electronics don't like voltage spikes, makes the processors do funny things...

 

my $0.02 worth

2004GMC1500CC Enthusiast

2004GMC1500CC

Posted
Posted
I have a 99 Yukon with the 5.7 engine. I've owned the truck about nine months, it had 78,000 miles on it when I got it (97,000 now). I noticed it would cut out then, but it would only do it for maybe half a second and it only happened three or four times during the whole nine months. It didn't seem to be a big problem but there was always the question in the back of my head what it was. Well, this past weekend we pulled a trailer on a 1000 mile trip and the problem has gotten much more serious. After a bout of stumbling it would clear up and run perfectly, I thought it might be dirty fuel injectors and put some injector cleaner in the tank but that didn't help. Now it's starting to do it to the point where I'm wondering if it's going to quit all together.  When it starts doing it the service engine light might flash but not stay on. I took it in to get the codes read but since the light didn't stay on they said there was nothing to be read (I thought there may be stored codes). Lately when it has a stumbling episode the ABS light will come on and stay on until the truck is shut off and restarted. I've replaced the fuel filter, the cap and rotor so far and dumped in another can of injector cleaner. The engine always idles perfectly regardless of how it's been running. I think the fuel system might be part of the problem since it seems to happen more while the engine is under load, but it will give me trouble sometimes whille going down a hill too.  If I give it full throttle when it's stumbling (trying to "clear it out") the engine will ping and there's a spitting sound under the hood. I'm wondering if an electrical problem is the cause since the ABS system is affected. I thought about the plug wires but we drove through a fair amount wet weather and it didn't make the problem any worse. Could it be the coil? Please help!!  I have another long trip in a week and all my money has to go for gas, otherwise I'd already have it at a shop! Thanks... Bill

 

 

 

 

Although at your mileage its unlikely it is behaving like my truck did when the fuel pump was dying.

Guest chevydeerhunter

Guest chevydeerhunter

Posted
Posted
Although at your mileage its unlikely it is behaving like my truck did when the fuel pump was dying.

 

+1 on the fuel pump.

willlgord Enthusiast

willlgord

Posted
  • Author
Posted

Although at your mileage its unlikely it is behaving like my truck did when the fuel pump was dying.

 

 

 

 

Just wondering, why do you question my trucks milage? Does the fuel pump usually last longer?

I think the fuel pump or the electrical for it might be the problem. I've also noticed (but wasn't sure of it before) that the fuel gauge drops when the engine stumbles. I'm thinking that the electrical connection to the fuel pump and tank sending unit is the problem, does the power for the sending unit go through the pump relay too? (probably not) Maybe it's a bad relay if it does. I haven't had time to check this out yet.

Thanks for the help.

  • 1 month later...
willlgord Enthusiast

willlgord

Posted
  • Author
Posted

I found the problem!! Originally I was pretty sure I had a fuel problem so I replaced the fuel pump, filter and pump relay... didn't change a thing. After talking to a shop and showing them the problem I decided it was an ignition problem after which I replaced the coil, plugs and plug wires (I had already put a new cap and rotor in). The truck ran great for a few days then it started stumbling again. It got worse and worse until I noticed it happened mostly after I had hit a bump in the road. My next suspected area was the ignition switch but pounding on the steering wheel to shake the switch didn't do anything so I knew there had to be a bad electrical connection someplace. I probed around under the hood and found that a bundle of wires routed from the top of the engine on the passengers side front had come loose of its clip and was touching the exhaust manifold at the front of the engine. The heat had melted away the insulation (even though the wires were wrapped in some heat resistant tape) and the wires were grounding out now and then (from hitting bumps....speeding up...slowing down). I looked at a friends 99 Tahoe and his clip had let loose also and his wires were pretty close to the manifold too so I'm wondering if this is a common problem. driving.gif

Bill

 

P.S. I figure the reason the truck ran better for a few days after putting the coil, plugs and plug wires in was probably from moving the wires around while working on the truck and they took a while to settle back onto the manifold again.

freakyt Enthusiast

freakyt

Posted
Posted

Oh man, that's a bummer. How did you fix? Tape up all of the melted wires with black tape?

 

Well, on the bright side, you've replaced many of the parts that go at about 100k :driving:. Just do the alterator, starter, and water pump, and you should be able to go for another 100K!

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • Deadwood
      10L1000 anyone with High Mileage ? I hate Damocles....

      By Deadwood · Posted

      New member here, very long time occasional guest. Saw this thread, thought it would be a good time to contribute someting. It is only my experience and not a claim that everyone will have the same.   I bought my '20 3500 L5P new and have put 99.9% (literally) of it's current ~400k miles on it myself, with over 50% of that towing loads between 4k to 15k, and to me this truck has been nothing short of amazing. For the first 235k I had zero issues, and from there until 321k I replaced a NOx sensor, two failing glow plugs, and three of the notorious injector connectors. I believe this truck is in part, a testament to good luck, but also good care and following a decent maintenance schedule (I also keep meticulous records.) As a result, it looks as good as a well cared for 70k rig, up and down, inside and out.   At some point before that 321k mile mark I began to get a little spooked about the 10L1000, especially the valve body. Word of mouth about potential issues prompted me to jump on the net to sift through all the noise and determine what all the fuss was about. I routinely take long trips, coast-to-coast and points in between, so roadside breakdowns can be '...a thousand miles from nowhere' and a bit of a challenge, and though I had no issues, my guard was up and activated.   And then I stumbled across a chance to salvage some parts off a new 2025 that had been wrecked in transport. I grabbed a few wear items (alternator, pulleys, etc.) and on a whim asked what the ten speeder would cost me. It was cheap...really cheap. I knew some changes had been made in the '24+ version 10L and were supposedly not compatible, but I called service/parts at my local Chevy dealer and asked why and they didn't know. A call to a well known aftermarket transmission outfit revealed it was very likely it would be fine, but to them not 100% sure.   Because it was cheap (really cheap) and I was spooked, I took the chance. Had it installed by a local shop and it worked like a champ, shifted just like the original. At it's first service at 37k, I had the shop put in a Next Gen valve body kit, which after some initial hiccups and rough shifts, smoothed out though with somewhat firmer shifting.   All that said, I have a very serious concern about my newer transmission as just two weeks ago it suddenly began to exhibit a strong reluctance to engage forward or reverse. It was a bit past due anyway so I took it in for service. The reason it was sticking was due to 'glitter' in the fluid clogging the filter...not good folks, often indicates a converter giving out. We ended up going ahead with the new filter and fluid, first to see if it would move and shift, and then if so buy me a little time. It did, and I've driven it over a thousand miles and it is shifting smooth, no noises or slipping. Regardless, it looks like a third gearbox is in my future so I can resume taking long trips with some confidence. In the very short term, my curiosity will have me examining the fluid to check how much glitter has reappeared.   An earlier poster had alleged, in the context of 10L100 failures, that it is another example of how we seasoned citizens somehow descend into hysteria, lose control of our senses, and react irrationally after brief encounters with the idiocy of the internet infosphere. Let me say (and I have used and abused said internet since it's infancy) there is no segment of the populace that has a corner on over-reaction to digital garbage. Just as my offering of experience in this arena is purely anecdotal and should not be considered gospel or all-encompassing, I believe it is still worthwhile information to consider, along with other relevant anecdotal experiences about things like complex transmissions, especially when balanced with other sources.   So to answer the original question, yes I got high miles out of my first 10L, trouble free for 321,000. Now I really wonder how much longer it would have went. Did I 'overreact' to the internet ghouls by replacing a 'good' one with a 'bad' one? Maybe. Who knows, the thing might have taken a puke a 100 miles later. So I'll just fix it again, then move on and start thinking about all the other stuff that will eventually wear out. It still has the original brakes (they're at ~60%), original injectors/pump, turbo, water pump, etc....pretty much original everything. Knock on wood.
    • swathdiver
      6 Speed vs 8 Speed

      By swathdiver · Posted

      At peak temperature.  They get to cool down and warm up more, especially those with the external cooler.  I have three GMT900s and one of them has over 225K on its original transmission.  Fluid gets changed about every 36K miles, all of it.     It's not the bean counters, it was the government.  They had to meet CAFE standards and other government requirements.   To get around that, we tune them and modify them to our liking.
    • GMCustomerService
      Will not stay in Reverse

      By GMCustomerService · Posted

      Our customers' safety isn't something we take lightly. To ensure you get the proper assistance for your truck's repairs, please fill out the form at https://s.chevy.com/support-request with all pertinent details including your username.
    • GMCustomerService
      2026 Z71 Forward and Rear Park Assist help

      By GMCustomerService · Posted

      We appreciate you sharing your experience with your truck. To ensure we get you the proper assistance, please fill out the form at https://s.chevy.com/support-request with all pertinent details including your username.
    • newdude
      Radio Update

      By newdude · Posted

      PCM?  These don't have a "PCM".  Powertrain Control Module.  They have an ECM (Engine Control Module) and TCM (Transmission Control Module).   Do you mean update the radio?     You can check what version you have in the settings page.  Should be Y181 but there might be a newer build they can update it to.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...