GMC 6.0 gas running rough
Printed From: Unofficial Allis
Category: Other Topics
Forum Name: Shops, Barns, Varmints, and Trucks
Forum Description: anything you want to talk about except politics
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=203391
Printed Date: 21 Aug 2025 at 10:25am
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Topic: GMC 6.0 gas running rough
Posted By: Thad in AR.
Subject: GMC 6.0 gas running rough
Date Posted: 26 Sep 2024 at 5:46am
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I recently thought I got some bad gas. I ran a can of sea foam through it after a fuel filter change. Didn’t seem to help. It runs normal down the road until you start to pull a hill then it will sputter. If you gas it and kick it down it clears up and does fine. Also sputters when taking off from a stop. No engine lights are on. My next step will be plugs and wires. Should I get the kit with coils as well? Any other ideas? It’s due plugs and wires anyway but I’m hoping that’s it. |
Replies:
Posted By: ekjdm14
Date Posted: 26 Sep 2024 at 7:17am
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May well be no warning lights on, but you could do a lot worse than look for any codes if you have access to a reader. Many issues can be "pending" meaning the light won't be triggered until it occurs a given amount of times but you'll still have a code or two, also live data can give clues (things like comparing MAF or MAP readings at a given RPM with known-good data available online, which can tell out a vacuum leak, or long term fuel trims being more than 10% either way giving you a clue as to whether it's going rich or lean, or in your case misfire counters may tell if it's a specific cylinder/s a single bank or the whole engine acting out). Still do plugs/wires as it's due, but don't "parts cannon" anything else without having some direction from the numbers.
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Posted By: Hubert (Ga)engine7
Date Posted: 26 Sep 2024 at 8:09am
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I had basically the same problem with my F150, 5.4 engine, but it did finally show a cylinder 5 misfire. It threw this code twice but cleared on it’s own both times. I figure it may have been gas with too much ethanol. It has run good after a couple of fill ups from a better gas station. I hope it’s not the ECM wanting to go south on me. ------------- Just an old country boy saved by the grace of God. |
Posted By: desertjoe
Date Posted: 26 Sep 2024 at 8:13am
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Well,,Ole Buddy,,those right there are the issues that make you want to light a fire in it,,,BTDT,,,A Good OBDII reader is what is needed for guidance for a starting point,,,,,AND ,,,I happen to have one,,,,
 if you can keep ole Faithful running for a bit longer,,,,I'm thinking I'll be able to hand my OBDII to you before too long,,,,, |
Posted By: Thad in AR.
Date Posted: 26 Sep 2024 at 8:39am
How long??? 😀 |
desertjoe wrote:Posted By: Pat the Plumber CIL
Date Posted: 26 Sep 2024 at 9:10am
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What year, I had the same problem with a 2000 vortec. On the fuel bar there is a small rubber hose attached to fuel pressure "gizmo" on the bar . Pull hose off ,if fuel squirts out diaphragm inside has ruptured and is messing up fuel pressure to injectors. Mine was a 5.3 but was doing exactly what yours is . Wish I knew exact terminology and may not be related but easy fix it it is. Fuel pressure regulator maybe ------------- You only need to know 3 things to be a plumber;Crap rolls down hill,Hot is on the left and Don't bite your fingernails 1964 D-17 SIV 3 Pt.WF,1964 D-15 Ser II 3pt.WF ,1960 D-17 SI NF,1956 WD 45 WF. |
Posted By: Coke-in-MN
Date Posted: 26 Sep 2024 at 9:38am
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Fuel pressure regulator is one item that was a recall on engine , other thing is dirty fuel rail - have codes read . bad EGR is another item on list . ------------- Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel. |
Posted By: Gerry D17
Date Posted: 26 Sep 2024 at 12:44pm
| Run all the gas out of the tank .Change plugs, wires and filter fill with fresh gas and if that does not help go to a shop and get them to diagnose it. JMO |
Posted By: HudCo
Date Posted: 26 Sep 2024 at 6:38pm
| check misfire counts probley bad coil |
Posted By: Ed (Ont)
Date Posted: 26 Sep 2024 at 6:46pm
| Fuel pump? What year is it and what mileage? |
Posted By: Darb210
Date Posted: 26 Sep 2024 at 8:07pm
| clean the throttle body butterfly plate!! |
Posted By: Thad in AR.
Date Posted: 27 Sep 2024 at 5:32am
2000 just replaced the fuel pump about 3 months ago. 600000 miles on it. |
Posted By: Gary
Date Posted: 27 Sep 2024 at 8:16am
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WOW A GMC Gas Pick-up with 600,000 miles on it, and it's just starting to Sputter a bit. Amazing! but true. G |
Posted By: ekjdm14
Date Posted: 27 Sep 2024 at 10:46am
Well, to give the thing it's dues it is a 2000 model so a whole lot less complicated than more modern trucks. (not up on my American vehicles, would this be an LS or an old-skool SBC?) 600k though, that's impressive no matter what era it's from. |
Posted By: Thad in AR.
Date Posted: 27 Sep 2024 at 11:56am
LS 6.0 |
Posted By: Gerry D17
Date Posted: 27 Sep 2024 at 1:43pm
| I bet you did regular oil changes. That's the only way to get high mileage out of engines.I have a 6.0 with 400,000 and change oil and filter every 3000 miles. Castrol GTX 5-30 and only WIX filters.Never added oil between oil changes. I hope you sort out your issue. |
Posted By: Thad in AR.
Date Posted: 09 Oct 2024 at 4:47pm
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Took the truck in and had it scanned today. Mechanic says it’s fuel related. Checked the fuel pump and regulator and says it’s normal. He thinks it’s injectors. He priced me injectors for near $800.00 I found some at parts geek for $138.00 Would these cheap ones be a mistake? They had good reviews |
Posted By: AllisFreak MN
Date Posted: 09 Oct 2024 at 5:34pm
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For a truck with 600,000 miles on it? I think I'd roll the dice on the cheap ones. ------------- '49 A-C WD, '51 A-C WD, '63 A-C D17 Series III, 1968 A-C One-Seventy, '82 A-C 6060, '75 A-C 7040, A-C #3 sickle mower, 2 A-C 701 wagons, '78 Gleaner M2 |
Posted By: steve(ill)
Date Posted: 09 Oct 2024 at 10:21pm
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i have used aftermarket injectors and coils with good luck.. ------------- Like them all, but love the "B"s. |
Posted By: Thad in AR.
Date Posted: 10 Oct 2024 at 5:55am
My thoughts exactly. The truck wouldn’t bring $800 if it had the new $ 800 injectors in it. |
Posted By: desertjoe
Date Posted: 11 Oct 2024 at 6:38am
I don't know,,,I've rode "Shotgun" in Thad's trk before and it is very well kept and engine sounded great all those times,,,,,
 I wouldn't hesitate on the aftermarket injectors,,,I've had good luck on using them lots of times. I've never tried SeaFoam and some say it works many Wonderfuls,,,,,,? |