I have a 1999 Chevy Silverado 2500 HD 4WD with a 6.0L. Last week I was traveling the wide open spaces of Wyoming when all of a sudden it died on me while in motion. Since I was a hundred miles from the nearest town and out of cell range I dived in to a roadside mechanic showdown, which of course I lost and ended up trailering it back to town twelve house later. The next day I changed out the fuel regulater, the fuel filter and the fuel relay switch only to find that it was the fuel sending unit, which I ended up replacing it as well. All went well and was going fine until today, (another 250 mile road trip), when it did the same thing to me though this time I was luckily able to get it started and back to the ranch. I have reached the end of my limited mechanical knowledge and am looking for any help that I can use in solving this issue... and thank you in advance for taking the time to read this post.

 

any dtc set or theft deterrant/security lights on?

If you think the problem is fuel related you should put a fuel pressure gauge on it and test fuel pressure when the problem is active. it fuel pressure is ok. check for spark with a spark tester when the problem is active.

 

Yeah, I tested the fuel pressure right after I installed the new fuel sending unit... it's steady at 45 psi. I have good spark though a P0300 & P0305 General Misfire Code appears on the OBD I/II Code Reader that I have in the "enhanced reading" but it clears out on its own after a hundred miles or so. I am beginning to believe that this could be the ECM though I just installed a new one not two months ago. Could the dealership have programmed it wrong or not programmed it completely? I am also wondering if I should take it to an independent shop and have them do a full diagnostic on it....

Thanks for the help, I am at a loss here and need all that I can get.

 

45 psi is low, trying monitoring it while driving or at different rpm ranges parked

 

yep, you should have 55-62psi. If you watch live fuel trim during a wot or hard acceleration, I bet the fuel system is adding fuel.