Help - Sudden stalling of 6.5 Suburban

[Jochen Woern]

Had some problems lately with my Sub and can not figure out what is going on.

Below, I will try to describe the sequence of events in the hopes that anyone can shine some light on this scenario:

- About 4 weeks ago, I tried to start the Sub in the morning and the Wait to Start (WTS) light would not come on. Truck would turn, but not fire. I try this for a while and eventually the WTS light comes on, truck fires as it should and runs fine.

- About a couple of days later, same situation. When the truck finally starts and I let it run in the driveway on idle, the truck dies and shuts off. Truck eventually starts and runs for a few days with no issues.

- Next situation was that everything worked as it should in the morning, but as I proceed to work, the truck stall/shuts itself of as I am driving. Pulled over to the side of the road, at first once again no WTS light coming on, after a few minutes and tries, truck runs again.

At this time I decided to bring it to a good friend of mine who owns a repair shop, he is NOT a diesel mechanic but I thought I have him look at it since it would not cost me anything. He has the truck for a week, checked all the electrical connections and grounds and all he could find was a somewhat loose battery connection. He keeps the truck a few more days, drives it, starts it every morning early when it is cold, but the truck NEVER shuts off on him. He and I finally decide that it would be ok for me to pick it up so I did.

- Truck runs great for about two (2) weeks, then it stalls/shuts itself of again in traffic. I get it started again and I take it home and at that point I am thinking it must be the PMD again. The Stanadyne unit I had installed was/is only 11 month old, but I thought I would try a new DTech which I ordered from Pensacola Diesel and I installed it once I receive it.

- I install the DTech on the FSD Cooler and all works out great, I fire the truck and it starts at the first turn, runs on idle in the drive for at least ten minutes and the truck dies once again for now apparent reason.
I try to get it started again but the WTS light once again does not come on so truck does not fire. After about two/three tries, the truck dies on me and nothing happens anymore, DEAD as a doornail.

- Could not get the truck started again, so I am calling the tow truck to get me to my GM Dealership, Mike Daugherty Chevrolet in Sacramento.

- I give my service advisor the whole story and I also inform him that I installed a brand new PMD.

The dealership tells me that the batteries are completely done and I needed new ones. I have the truck for three (3)Years now and I still had the batteries installed which the truck came with. So I guess it was ok for them to be toast.

- In order to continue to troubleshoot, the dealer installs a new set of batteries. My service advisor tells me that weak batteries can be the cause for the WTS sign not to iluminate and the glow plugs/relay not getting enough juice. While they take out the old ones, my service advisor informs me that instead of 2 batteries with 800 AMP Cranking Power, I am having one with 750 and the other with 850? Could this already be an issue?

- Dealer keeps the truck and they tell me they have checked everything:
1. Fuel is clean with no bubbles
2. Fuel Filter is good (which I had replaced about 7k miles ago).
3. Fuel Pump/Injection Pumps are good, we are getting steady fuel pressure as it should be.
4. With the new batteries, all cables and connections were checked once again and all is good.

- Dealer kept the truck now for three working days, drove it, ran it and left it idle for quite some time and my service advisor used the Sub today for a 50 mile round trip where he says the truck ran awesome, never missed a beat and so far the truck has not shut off while at the dealership.

I will pick it up tomorrow and am wondering what it could be. I am almost willing to bet that it will shut of on me once I am in rushhour traffic, never fails.

WHAT IS MY PROBLEM, DOES ANYONE HAVE ANY HELPFUL ADVISE?

Many thanks in advance.

[More Power]

Sorta sounds like an electrical problem.... you know... battery terminals, grounds, etc. If you're lucky the new batts and tightened terminals will solve the problem. :)

By the way, the best advice is to install a matching pair of batteries (age, brand, & capacity).

Jim

[N9Phil]

If it was me, I would go back to the dealer and have him replace the 750 with an 850 CCA battery. I always put in the largest CCA batteries that will fit in the holders. I believe that when you have batteries hooked in parallel they take on the characteristics of the weakest. In your case (750) CCA. It might not be a problem for you but I have vehicles sitting out in the weather and when it gets below zero, I want all the cranking power that I can get. Also remember that diesels have to turn over at a good clip in order to start. I want everything in my favor.

N9Phil

[donbfishin]

Delco does make a 1000 CCA battery... Make them get 2 of those for trouble free performance.

[DickWells]

Lets hope your problems don't return. IF they do -- start working on it yourself.
Here's what happened to me, back before I put in a mechanical pump. My record was about 3K miles without a problem back then.
*Found a loose ground at the trans dip-stick mounting tab, right rear of engine. No problems for a while.
*Bad ground at top of frame, near the starter. Put a 5/16 SS bolt through the frame from under the fender liner behind the R-F tire. Double nutted the ground tab with SS nuts and lock washer. That's when I got over 3K without a problem
*Found a bad connection in a little plastic sealed block in the wire harness up by the intake plenum and IP. That one took some searching. Shut down everything when I flexed the wires around that little 2 inch block. I simply cut the offending wire both sides of the block and jumpered around it with a new piece and soldered it in. Mind you, this was after I had already put in yet another FSD, on the road in Florida! Not nice being away from home and having the engine quit, or skip, or both, and having all the instrument lights flicker, or go out. In the dark, in the rain, in a strange land, like Florida. Yuk.
The thing is, with the 6.5, you can almost bet the thing will run enough to get you back to the cave. It almost always turns out to be some little Will- O-The-Wisp-thing. Anoying and scary, but fixible. That's why I still love my old Sub.
Good luck.
Dick Wells:)