03 GMC Sierra HD shut off while driving

[chesapeakechuck]

My duramax just shut off while driving on the freeway the other day. I was towing a light trailer and was really in a bind. Ended uphaving the thing towed to a shop because I didn't have time to troubleshoot it myself. The filter is almost new and the truck didn't give me any signs of dying prior to it just turning off. I tried to prime the filter and then start the vehicle, but it would not start. It clearly was not getting any fuel. I opened the pit cock on the bottom of the filter to see if I had sucked up water from bad fuel, but it was empty. Priming the filter did not seem to pull any fuel. The shop said it started right up for them (48 hours later) and they are looking at it. I am hoping this is not the injector pump. I just put injectors in it less than 10K miles ago (truck has only 100K on it).

Any thoughts? I wish I had hooked up my code reader to it. I am worried that the GMC garage is going to put it to me.

[chesapeakechuck]

The GMC shop said they had the problem sorted out yesterday afternoon---claimed that I had sucked air into the fuel filter from running the fuel tank down to 1/4 level (first time it's ever been that low with me as an owner). Anyway, went down to pick it up and it died as the diesel tech was driving it out to meet me. Ugh. Upon closer inspection, the tech noticed that the primer valve was ''sucked in''. After an hour the suction would bleed off and you could again get prime, allowing the truck to start. I guess he is going to look for possible debris in the fuel line somewhere. He checked all of the rubber connecting fuel lines to see if there was an old one which was collapsing and causing the vacuum, but everything looked good thus far. What a pain in the tail. Had to get a rental car for a day or so---it's like driving a shoe.

[Kennedy]

Sounds like it could be something in the tank pickup. I'd definitely recommend adding a lift pump as well. This takes care of replacing all the non pressurized hose and pressurizes the rest of the system.

[chesapeakechuck]

Truck is fixed. Looks like an old fuel line was collapsing, causing a fuel restriction that resulted in the pump losing prime. I am going to invest in a lift pump per your suggestion.

[chesapeakechuck]

This is a follow up to my original post of about a month ago. On Dec 23 my truck shut off again while driving down the freeway in heavy traffic. Ugh....The same thing happened to it as what had happened a month earlier. The plunger on the fuel filter was sucked all the way down due to there being a vacuum in the line. A month earlier I had the fuel lines replaced by the GMC garage when the truck was experiencing the same symptoms. They said they found a collapsed line and that is what was causing the fuel restriction. Well, a month later the problem has returend (and the fuel lines are only a month old). Ugh.

Has anybody had this type of problem with their LB7? The truck only has 104K on it. It's a 2003.

It seems like if there was a clog in one of the fuel lines that the problem would not be intermittant like it is. The dealer is having a hard time diagnosing the issue.

[rapidoxidationman]

Did the dealer replace only the offending fuel line or did they get proactive and replace ALL of the soft lines between the tank and fuel filter? Sounds like they went the cheaper route and the problem reared up again in another soft line of the same vintage.

Did the lift pump not make any difference???

[chesapeakechuck]

I am not sure now if they just replaced the offending line or all of the soft lines back to the tank. I am inclined to think now that they only replaced one that they found issue with, but I will verify this later when I speak to the dealership.

I haven't had a chance to put the lift pump on yet...I think I will do that as soon as I get the truck back.

I suspect that the problem is another soft line collapse----the truck is ten years old, so this wouldn't be entirely unexpected. If this proves to be the case, I am going to make for certain that all of the soft lines are replaces so as not to revisit the same problem in a few weeks. I am tired of getting towed off of the freeway :).

[Kennedy]

I'd recommend checking the system restriction too if it is sucking down the primer pump.


The little bit of remaining "soft line" is crimped in place with the exception of a pair of hoses at the filter housing and a short piece at the CP3. Adding the lift pump should take care of all but the first 4' of hose and if you use a good hose here it will not collapse.

[chesapeakechuck]

The GMC diesel tech says that he can find nothing the matter with the truck and they want me to come and pick it up later today. WTF? I have had this stupid thing towed twice in the past 5 weeks and I'm pretty sure I didn't make up the problem in my mind. They said that they ran the truck a hundred miles and idled it for over five hours without being able to reproduce the problem that causes the vacuum in the fuel line. I am beyond disgusted and almost ready to buy another toyota. I don't know what to do at this point. I kinda figured that the GMC garage would get this sorted out.

[Kennedy]

You can take the matter of testing the restriction into your own hands:


http://www.kennedydiesel.com/images/Dmax-fuel-filter-rest1.gif

[rapidoxidationman]

I wonder if the original "fuel line collapsing" was caused by something plugging the fuel pickup in the tank? A piece of plastic wrap or some such that would not be dissolved by diesel could slosh around in the fuel tank unnoticed until it got sucked onto the pickup and restricted the flow of fuel to zero and caused the symptoms you have. That'd be pretty tough for anyone to diagnose... What a great April Fool's joke, eh?

Lift pump wouldn't help at all in that case...

[chesapeakechuck]

That actually makes some sense. The vacuum goes away after the truck sits for an hour or so, and the pump on the filter slowly emerges from its frightened turtle position. I would have been much happier if they would either have gone ahead and changed the remaining soft lines out on the truck, or offered me some other possibility (no matter how remote) as to what the problem may be....Instead, I have just been told to just come and get it. How frustrating. I am leaving work here in Los Angeles shortly and have to run down to the dealer to return the rental car and "pick the truck up" in its current state. I don't trust it to drive it anywhere, most especially the 91 freeway in Orange county, Ca. at rush hour.

If figures that I probably have the only one of these trucks in existance that's pain in the rear. Seems like everybody that I know who has an LB7 is happy with it, not withstanding some injector issues (which are well documented).

I am seriously thinking of trading it tonight. Ugh.

If I don't have a complete meltdown at the dealership later and I decide to bring the thing home, I wil order the lift pump tonight and install it asap. . It sure can't hurt. I just looked at the kennedy pumps and it will be a piece of cake to toss one on next week.

[jbplock]

A bad fuel tank cap could might also be a cause of your problem.

[cabletech]

If it were my truck...
1. I would either replace fuel cap or drill a small hole in it so it was always vented.
2. Drop the tank and look for something plugging the fuel pick-up.

Jay

[Kennedy]

The LB7's have a plastic squiggly vent tube that originates at a boss on the top rear of the tank and runs down behind the tin shield. Later models have a large 5/8" hose that vents to the fill assembly.

I don't believe I've ever checked a LB7 fuel cap to see if it vented but a quick wipe dry and a lip lock and you'll know. The taste isn't overwhelmingly bad or anything.

To block the pickup would be pretty tough to do, especially intermittently as it has a large surface area and resides within a "cup"

[chesapeakechuck]

Well, I was handed the truck back and told that there is something the matter with it, but we can't reproduce the problem, so good luck. So now I have a vehicle that i have to drive on Orange County freeways that's subject to shutting off whenever it feels like it. That's reassuring when you're on an 8 lane freeway. If I didn't own this vehicle free and clear, it would be gone in an instant.

Anyway, the diesel tech thinks that the problem almost certainly is being caused by a collapsed fuel line (one of the ones that are harder to get to and that were not replaced already). The soft fuel lines under the hood, on either side of the engine, have been replaced. So has the short connector line immediately under the driver's door. The diesel tech believes that the line comming out of the fuel tank is the one that's causing the problem. I guess this line is convienantly sandwiched between the top of the tank and the bottom of the bed, making it a lot of fun to access.

Has anybody had problems with this particular section of fuel line? Is getting to it very difficult? I can't imagine that dropping the tank is too difficult. I have to do something pretty soon because I cannot drive back and forth to work everyday just waiting for the stupid thing to crap out on me in the middle of Los Angeles traffic.

[rapidoxidationman]

So the tech feels like he knows what's wrong but doesn't want to get his hands dirty trying to fix it???

I see two courses of action:

Hello, GM Customer Service (http://www.thedieselpageforums.com/tdpforum/member.php?u=36110)? Can you light a fire under this lazy dealer diesel tech's ass for me please?

Find a local mechanic who knows what the hell he's doing and isn't afraid to do it. There's gotta be someone in the urban jungle that is Orange County, CA... Maybe somebody here knows.

[chesapeakechuck]

I already called GM customer service up in Detroit and let them know what is going on...I pretty much got no reply from them, either. I've only had this truck for 7 months now, and in that time it has undergone a complete injector replacement and now stranded me two times along the side of the freeway due to this latest problem. It's only got 104K on it now...maybe I know why the milage is so low now. I ran Jap trucks for the past ten years and finally got up the nerve to go American again. I am wondering if I made a mistake at this point as my Jap trucks never gave me any trouble whatsoever. I'm not giving up on this thing yet, but it does have me pretty disgusted.

[chesapeakechuck]

I am looking at trying to fix the damn thing myself at this point. At least my labor is free :). I want to replace the rubber fuel line that comes off of the tank. I suspect that this may be the thing that's causing me the trouble. I know the standard protocol for doing this involves removal of the bed. My truck has a long bed and I am a one man band---kinda hard to remove the bed without enlisitng the help my alcoholic buddies down in San Diego. That may be an up hill battle. Is it possible to drop the tank from the bottom to gain access to the soft outbound line? I was thinking of running the tank down to a quarter (I never do this) to lessen the weight and slosh factor, and having at it. Any thoughts from anybody?

I believe the GMC garage has replace all of of the rubber lines forward of the return fuel cooler, so I am guessing that this last remaining rubber line is what is causing the issue.

It's almost impossible to get the line to collapse on demand, and this is what is giving the GMC garage so much grief. If the truck is running fine, it is tough to diagnose the problem. It has run for 4 weeks inbetween incidents (roughly 2400 miles). I don't want to wait for it to strand me again before I try something a bit more proactive. Any advice or help would be greatly appreciated!

[Kennedy]

Sounds like it could be something in the tank pickup. I'd definitely recommend adding a lift pump as well. This takes care of replacing all the non pressurized hose and pressurizes the rest of the system.


I'd recommend checking the system restriction too if it is sucking down the primer pump.


The little bit of remaining "soft line" is crimped in place with the exception of a pair of hoses at the filter housing and a short piece at the CP3. Adding the lift pump should take care of all but the first 4' of hose and if you use a good hose here it will not collapse.



Anyway, the diesel tech thinks that the problem almost certainly is being caused by a collapsed fuel line (one of the ones that are harder to get to and that were not replaced already). The soft fuel lines under the hood, on either side of the engine, have been replaced. So has the short connector line immediately under the driver's door. The diesel tech believes that the line comming out of the fuel tank is the one that's causing the problem. I guess this line is convienantly sandwiched between the top of the tank and the bottom of the bed, making it a lot of fun to access.

Has anybody had problems with this particular section of fuel line? Is getting to it very difficult? I can't imagine that dropping the tank is too difficult. I have to do something pretty soon because I cannot drive back and forth to work everyday just waiting for the stupid thing to crap out on me in the middle of Los Angeles traffic.




I am looking at trying to fix the damn thing myself at this point. At least my labor is free :). I want to replace the rubber fuel line that comes off of the tank. I suspect that this may be the thing that's causing me the trouble. I know the standard protocol for doing this involves removal of the bed. My truck has a long bed and I am a one man band---kinda hard to remove the bed without enlisitng the help my alcoholic buddies down in San Diego. That may be an up hill battle. Is it possible to drop the tank from the bottom to gain access to the soft outbound line? I was thinking of running the tank down to a quarter (I never do this) to lessen the weight and slosh factor, and having at it. Any thoughts from anybody?

I believe the GMC garage has replace all of of the rubber lines forward of the return fuel cooler, so I am guessing that this last remaining rubber line is what is causing the issue.

It's almost impossible to get the line to collapse on demand, and this is what is giving the GMC garage so much grief. If the truck is running fine, it is tough to diagnose the problem. It has run for 4 weeks inbetween incidents (roughly 2400 miles). I don't want to wait for it to strand me again before I try something a bit more proactive. Any advice or help would be greatly appreciated!

Sorry but broken record here again.

Add a lift pump kit (hint hint) that replaces the section of line from the tank to the first steel line. I'd bet that the money wasted to date would darn near pay for a quality kit and then some.

On the LB7 what I do is remove the rear driveshaft and then bend down the galvanized heat shield to gain access to the sender connection. While I generally dislike using quick connect fittings (makes 2 connections out of one) this is where I will use them to save dropping the tank and ease the install.

If the next quick connect is rusted on then you'll want a tubing cutter to cut the steel line just ahead of the lift pump.

I've been in contact with numerous individuals chasing DTCs (typically P0087 and not engine shut down like this one) and hear the same thing over and over. "Replaced this line and than line, then the other. Thought we had it a couple of times, but always came back. To date every piece of hose in the system numerous times and still no luck."


Back to what I keep saying over and over: Add a lift pump that starts plumbing at the tank elbow. This way all line is put under pressure and no possibility of collapse. If the problem persists drop the tank.

If you want to be 100% sure then drop the tank, inspect thoroughly and reinstall.

[hapaschold]

i dont think that stock soft fuel line is full vacuum rated. even new it will collapse.

something is not venting to allow vacuum to break. fuel cap ? tank vent ? something is clogged.