2001 GMC 4x4 Yukon XL 8.1L. Shuts Down Randomly During Highway Driving. Please Help!

Sundevil11

My 2001 GMC 4x4 Yukon with 196,000 miles dies while on the highway. It usually occurs while doing highway speeds and on trips longer than 6 hours. Once it stalls it will usually start back up after 10 minutes. As with many other examples I've read on the internet, this is not an uncommon occurrence. For anyone who has experienced this issue, or knows what other people have fixed or had replaced on their vehicle to remedy this problem any feedback would be greatly appreciated. Here is what I can tell you about what has been replaced on my vehicle at this point.

Fuel pump x3
Cam shaft sensor
crank shaft sensor
gas pump (duel tanks)
PCM (power train control module)

This vehicle has now been to 5 GMC/Chevy Dealerships (across multiple states). No one at this time has pin-pointed the specific issue. To say this is frustrating is an understatement. I could go on and on about how dangerous it is but anyone who is aware of this issue already knows that. I just need to get to the bottom of it. Thanks for your time and hope that someone out there can help me.

thecardoc3

The cutting out issue can only be diagnosed while it is occurring. To do that, someone has to preset the testing in anticipation of it happening. Generally speaking when the engine cuts off you have either lost spark, fuel or both.
Once it is known what you are losing, then the testing shifts to why did you lose one or both of those and the testing gets reset for the next phase. With it taking some six hours to occur that is a very difficult behavior to reproduce so you would have to be an active participant in the testing. I could start by rigging some lamps to specific circuits and then when the car act's up you would have to report back which lamps remained lit and which ones did not. Then we could reset and do it again until the trouble area is narrowed down sufficiently. From that point there may be no other choice than for the technician to drive the vehicle and be ready to complete the pinpoint testing.

If you want a complete shot in the dark, have someone test/inspect the ground cable that goes from the right front frame rail to the engine block. That doesn't mean to just replace it, it means test it.

Sundevil11

thecardoc3 said:

The cutting out issue can only be diagnosed while it is occurring. To do that, someone has to preset the testing in anticipation of it happening. Generally speaking when the engine cuts off you have either lost spark, fuel or both.
Once it is known what you are losing, then the testing shifts to why did you lose one or both of those and the testing gets reset for the next phase. With it taking some six hours to occur that is a very difficult behavior to reproduce so you would have to be an active participant in the testing. I could start by rigging some lamps to specific circuits and then when the car act's up you would have to report back which lamps remained lit and which ones did not. Then we could reset and do it again until the trouble area is narrowed down sufficiently. From that point there may be no other choice than for the technician to drive the vehicle and be ready to complete the pinpoint testing.

If you want a complete shot in the dark, have someone test/inspect the ground cable that goes from the right front frame rail to the engine block. That doesn't mean to just replace it, it means test it.

Thank you for the feedback. The ground wire has been replaced and I forgot to list it in the items replaced/repaired. I do agree with you that because of the randomness of the engine failure it will take a mechanic to drive the vehicle and then diagnose the issue when it occurs. This however is going to be a difficult task to ask of a mechanic. Thanks again for the suggestions.

thecardoc3

Over the years I have solved quite a few vehicles with issues like this, it takes patience, and a well thought out game plan. It can be done, but we cannot earn a living while doing it. If we even charged a tenth of the time that is usually invested against something like this the stories could be something like "They charged me $XXXXX and still didn't fix it, all they did was go joyriding all over the place in it". Can't really argue with that because it fits the stereotype that everyone has wanted to push for decades. It is sad that happens because it really isn't accurate but that doesn't seem to matter.

Going in to a problem like this the vehicle owner has to agree to some kind of a testing fee and we have to establish a limit that if unsuccessful we won't go past. Truth is, in many cases while we don't charge more than what is authorized, the time against the car usually vastly exceeds what is billed. Then again there have been times when lady luck play's her hand and the problem shows up right away and lasts long enough to get to a solution the very first time it happens. I've kind of always laughed at those instances because to the vehicle owner it looks like magic or that the tech is a genius, and no it's neither of those. He/she just happened to get lucky with the failure event and went about following a normal routine and worked right to the source of the trouble.

That ten minute failure window is quite likely sufficient for me to prove what is going on the first and maybe only time that I would get to experience the failure. However getting that ten minutes of broken car to occur while I have the car is about like winning tonight's lottery.

airconman

This is a long shot, but I once had a Jeep Cherokee that would shut down randomly, usually on the highway at highway speed. Eventually I determined it was heat related. Always happened when the car was good and hot. Had it checked by a number of shops to no avail. Finally one guy took the time get it to fail. He determined it was due to a faulty relay. The jeep had a bank of 4 relays related to the ignition system and he replaced them all. $20 each.