Originally Posted by Tom Mitchell

VERY IMPORTANT WHEN YOU READ THIS NOTE THAT REPLACING THE CAMSHAFT POSITION SENSOR AS WELL AS THE CRANKSHAFT POSITION SENSOR THAT THE SENSORS WILL NEED TO BE RELEARNED UNLESS YOU HAVE THESE SPECIFIC METER TO DO THIS YOU WILL NEED TO TAKE IT INTO YOUR LOCAL MECHANIC OR FIND SOMEONE WITH A METER THAT WILL RELEARN YOUR POSITION SENSORS IF YOU INSTALL THESE WITHOUT RELEARNING THEM YOU WILL ASSUME THE PROBLEM DID NOT GO AWAY AND START TROUBLESHOOTING OTHER THINGS LEADING YOU AWAY FROM THE INITIAL PROBLEM IF YOU DO NOT HAVE THESE SENSORS RELEARNED,IT IS TRUE THAT SOME VEHICLES DO NOT HAVE TO HAVE THEM REAL EARNED BUT WITH GMC, CHEVY, AND ANY OF THE 5.3 L TYPE MOTORS THEY HAVE TO BE RELEARNED OR IT WILL NOT CORRECT ITSELF IN THE PROBLEM WILL NOT GO AWAY.

In the GMC and the Chevy Tahoe suburban etc what a fuel pump goes out it will not only a cup on hot days and it will not be intermittent restarting in just a few minutes or sometimes immediately after the vehicle has stalled, that's not to say that if your car stalls on a hot daythat you should dismiss a fuel pump either but simply understand that in 99.9% of the cases were a fuel pump goes out the vehicle only restarts once maybe twice the heat never has anything to do with it and then it will shut out completely,. SOLUTION.... MORE OFTEN THAN NOT IT IS GOING TO BE YOUR CAMSHAFT POSITION SENSOR WHICH IS under the intake manifold towards the back of the engine, and or your crankshaft position sensor yes these are two separate sensors your crankshaft position sensor is typically located under the motor you'll need to remove the starter to find it it's held on typically by a 10 mm bolt and they average about $25 to buy in town or $10 to buy online.MORE OFTEN THAN NOT THIS IS MISDIAGNOSED FOR A VERY LONG TIME BECAUSE IT THROWS NO CODES BUT ONE WAY TO TELL if it is your crankshaft position sensor is that when the car guys when you go to turn it over again you'll watch the tachometer very closely, if the motor is turning over but the tachometer is not moving whatsoever and the car won't start more often than not that is your crankshaft position sensor located below the motor because it is the sensor that tells you the RPM so if it's not working it's not reading.
Also this seems to effective vehicle only when it's hot outside temperatures over 80 degrees for myself it was anything on a hot day 84 or above, 88 degrees for sure I would come to a stop light it would be idling just fine and sometimes within 10 seconds other times within 30 seconds it would stumble and die, sometimes I would have to sit there for a couple minutes and then it would fire back up and do it again at the next light other times it would fire up within just a few seconds but again the problem would not stop. Then I would go out in the evening temperatures below 80° drive it all over town and back without one single issue day in and day out of this happening draws you to only one conclusion. The chances of it being a fuel pump are slim to almost done with these type of symptoms. The symptoms for the crankshaft position sensor as well as the camshaft position sensor are almost identical. My recommendation would be that if you were doing this yourself and you had the mechanical skills to watch the video on YouTube made by A-1 Auto and it will walk you through changing the camshaft position sensor the tools are relatively simple a 10 mm wrench with extension a fuel line separator 3/8, flat blade screwdriver, a vacuum for cleaning up around the top of the motor so no debris falls in not your wife's vacuum from the house by the way oh, you will need a Shop-Vac, of course you will need a new camshaft position sensor, and if I missed anything if you watch the video it will go into great detail step by step on how to change a camshaft position sensor in the Chevy and GMC Tahoe and suburban again this is by A-1 Auto on YouTube.
I was unable to find A-1 Auto crankshaft position sensor but I did find another very helpful video on YouTube by " 2carpros" and that was for changing the crankshaft position sensor.

YES THESE PARTS ARE TWO DIFFERENT SENSORS SOME PEOPLE AND SOME OF THE THINGS YOU WILL SEE ON THE INTERNET WILL TELL YOU THAT THE CAM AND CRANKSHAFT SENSORS ARE ONLY TALKING ABOUT ONE SPECIFIC SENSOR THIS IS NOT TRUE ALL CARS HAVE A CAMSHAFT AND A CRANKSHAFT EACH ONE HAS ITS OWN SENSOR IF YOU CHANGE ONE CHANGE THEM BOTH IF YOU MECHANICALLY INCLINED TO IF YOU GO TO A DEALER THE LOWER ONE WILL PROBABLY COST YOU ABOUT $200 INSTALLED WITH PARTS IF YOU'RE LUCKY MAYBE UP TO 300 BUT THE TOP ONE THEY WILL CHARGE YOU FOR PROBABLY SIX HOURS OR MORE BOOK TIME IN REALITY IT'LL TAKE THEM LESS THAN AN HOUR AND A HALF IF THEY KNOW WHAT THEY'RE DOING BUT YOU WILL PAY BETWEEN 3 TO $500 BECAUSE THEY HAVE TO TAKE THE INTAKE MANIFOLD OFF AND TO MECHANICS THEY THINK THAT WERE ALL STUPID, they make it sound like a process that it doesn't actually have to be the reality of it is a qualified mechanic that knows the fundamentals of a shop in his first 30 days would be able to have this part removed and the motor put back together in less than 2 hours, unfortunately mechanics get to rip us off so if you have to have this done don't be cheap and only put in 1 sensor, make sure you get the old sensor back and even go as far as tell them once they have the motor apart just before they pull out the old sensor you like to kind of take a look at things any reputable mechanic will let you view as long as it is safe to do so and does not interfere with the daily operations of the shop or the repair that is going on will have no problem providing to you to prove that the item was removed and a new one installed and it is up to the customer to make sure this happens as in many many cases mechanics do not replace this part but simply take it out clean it up and reinstall it to save $5 and charge you up words of a hundred for that part, depart cost less than $25 to us and cost less than $10 to them, but they will charge you $100 for the part alone so unfortunately of these are the symptoms religiously stalling and restarting on hot days above a certain temperature running great in the evening when it's cooled down acting like it's running out of fuel when you go to restart it acting as if it's out of fuel the firing up after just a few minutes sometimes shorter sometimes longer more often than not it will be your crank or camshaft position sensor you'll need to have them relearned and you'll need to replace both of them if you are having any symptoms as there's no way to test them accurately and they both give off the same issue and many times are both bad at the same time.

Originally Posted by cleveland63b

if you were dropping pressure then you needed the pump, I hope you sealed your access panel very well. The possible dangers created from that are not worth it in my opinion.