Chevy/GMC 6.2L and 6.5L Discussion of Chevy and GMC Trucks with 6.2L and 6.5L Diesel Engines

My truck is shutting off randomly again :(

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  #1  
Old 08-31-2015, 09:20 PM
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Default My truck is shutting off randomly again :(

So I have been here a little while now, and have been working on this truck monthly for a year. At 220K miles and 18 years, all sorts of things are starting to wear out. Just everything really. Plastic breaking off, bushings wearing out, the cab leaks when it rains....

Needless to say, I have become very familiar with the infamous "Detroit Diesel K1500."

I had to chase down the dastardly clogged fuel sock as my first test. Recently there was a no power black smoke issue that took some time, and two owners to figure out. Turns out the wastegate was not being controlled properly due to a vacuum leak somewhere.

Now I am getting random shut offs. Some facts: Plenty of diesel from a straight wired lift pump, a new filter manager with metal top cap, and a smooth as silk idle with plenty of power now that the wastegate being properly controlled. Grounds checked and rechecked. The EGR solenoid exit has been plugged with a vacuum cap.

Bleeding the fuel filter manager (will use FFM as an abbrev.) has been a quick fix recently. With the sock off I got down to less than five gallons before refueling, and went through some hills. (road hilly, not offroad hilly) It started to randomly shut off so I bled the FFM, thinking I got some air while fuel was low and sloshing around. This worked for a bit, when it cut off again I removed the filter completely and bled it again. This worked for quite some time.

Idling today it just shut off. No biggie at this point, as many 6.5 TD owner's can attest. However then it shut off again, and again, and again. Hell, now it wouldn't even idle for a minute without crapping out. Houston, we got a problem.

I bled the FFM, didn't work. Removed the filter and reinstalled, bled again. No dice. Meanwhile the straight wired lift pump is definitely gettin' her done and I am startin' to smell like a tractor. I wait a bit and am able to move it to a parking lot with a couple shut offs along the way. Finally I removed the fuel filter COMPLETELY and pumped it till diesel spilled out of the empty FFM. Shut the pump down. Then, with the air bleed way open I put the filter back in and turned the pump back on till nothing but diesel shot out; while the lift was running I tightened ring and the bleed valve down real snug (in that order)

That seemed to work, as I was able to make it to O'Reillys (they let me work on my truck in the parking lot, god bless 'em). The whole time I am expecting this thing to crap out. So tense, especially when in heavy traffic or when there is no shoulder to emergency park on.

They ran some codes and I got an EGR DTC. Well, it is capped off with vacuum plugs at the EGR and the solenoid exit nozzle, but I didn't think the PCM would know. Somehow, it knows. Maybe the MAP sensor is telling on me?

I tighten all the fuel connections and C-clamps, and then reinstall the EGR vacuum hose. On the way home I could tell it was real weak now, and the exhaust isn't burning clean anymore.

Is my EGR valve bad? Holy smokes, that thing is like 250 bucks! Is the EGR solenoid bad? I don't get it.

Honestly, it is a better move to install an F intake with turbomaster before spending that much money for a dumb emissions part.
 
  #2  
Old 09-02-2015, 05:46 PM
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So today it crank fine, drove it to the store and shut it off (about 5 miles)

Went to crank it back up and it cut off. Then it kept cutting off and would only idle for a minute or two before shutting off again. Hard starting.

I bled the FFM and it didn't help this time. Shut off over and over.

Then I fiddled with some connectors, not even unhooking them, and sat for another five minutes trying to get it to start and stay running.

All of a sudden she fired up and has ran all day like a champ. Didn't cut off again, started easy.

I just don't know at this point. Hate to say it, but could it be the PMD just acting squirrely?

I have heard there was a fuel cutoff solenoid somewhere, anyone know its location and symptoms?

It cuts off when the lift pump is straight wired. Bleeding the FFM doesn't seem to matter, so the air in line issue seems questionable.
 
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Old 09-03-2015, 04:04 PM
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Sounds like the ignition switch these trucks are notorious for this problem.
 
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Old 09-04-2015, 10:34 AM
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You might be right.

Other symptoms, the glow plugs don't stay on the right amount of time, or don't come on at all when it experiences stalling and I try to restart it. Like something isn't activating the glow plug system. Also the dash lights start doing funny actions.

If it is the ignition, do I replace the ignition lock (which needs replacing due to wear and tear and general wobbly-ness) and the ignition switch?

Let me use this forums search function...
 
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Old 09-06-2015, 08:06 AM
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The rubber thingy on the lock that you twist has twisted off, and lately I have had to move the steering wheel back and forth to get it to unlock.

If I replace that as well, how do I get the keys coded, and how much does it cost?

If I leave it, will just replacing the switch wiring solve the problem?
 
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Old 09-07-2015, 11:00 AM
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Ordered the switch and the lock. Will update results.

Got the OEM stuff on Amazon for about 130 bucks.

Supposedly the lock doesn't come with keys, and must be coded at the dealership.
 
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Old 09-09-2015, 10:55 PM
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Normally the lock cylinder comes with keys (but not for the doors) be careful when phishing the wires out for the ignition switch and DISCONNECT the batteries. But if the problem persists look into a PMD and relocation kit, the EGR should not shut down the truck.
 
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Old 09-10-2015, 08:56 AM
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Originally Posted by Dieselhead6.5
Normally the lock cylinder comes with keys (but not for the doors) be careful when phishing the wires out for the ignition switch and DISCONNECT the batteries. But if the problem persists look into a PMD and relocation kit, the EGR should not shut down the truck.

Already got the PMD relocated. I mentioned the EGR because I don't know why it is throwing a code if the vacuum is still going to the EGR solenoid, but not to the EGR valve. But, I think the MAP sensor is playing a role in the code.

My cylinder lock did not come with keys, and says it must be coded at a dealership.
 
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Old 09-10-2015, 01:13 PM
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You guys could have given me a heads up on the odd bolts that are used to hold the factory ignition in place. It is 3 or 3.5 mm torx male head. I went to a parts store and Lowe's and neither carries a torx socket that small.

Looks like it will have to be special ordered.
 
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Old 09-10-2015, 02:59 PM
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While removing the old ignition I noticed this thing was totally disconnected. Also , the electrical connector was disconnected and the tab was broken.

This same connector is on the new ignition switch.

Anybody have any idea what this thing is and what it does?
 


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