KR is with stock tune,patric g tune and jesse bubb tunes

in the past logs of their tune little to no KR. Keep in mind this this cranks like hell to start in the mornings,FP dropped to 35 lbs in less than 5 hrs with gauge on it.

 

It had a ck light they were to rich codes bank 1 and bank 2,I didnt note the code #s thinking it would come right back on,it hasnt maybe because ive been light on the throttle.

 

As long as those fuel trims are negative, its running rich. You can't expect the fuel system to hold pressure forever, otherwise there would be no need to prime the pump, would there? Only dropping from 45 to 35 in 5 hours is pretty damn good.

The KR may be coming from a rattle if Pat G's tune does it. Loosen and re-torque the knock sensors, check for loose bolts, etc.

 

not to highjack, but would you elaborate on " tuning time stamp"
haven't heard of that.

 

From what you are describing it sounds like the fuel pump is going out. You can have the correct pressure but it may not be the correct volume. When I have finicky problems like yours there is one simple test I do that while not textbook usually uncovers a low fuel volume problem.

If your fuel pressure test gauge has a bleed button on it KOEO prime the the fuel pump a few times and bleed all of the air from the gauge until you have a solid fuel column coming out. The start the engine let it idle for 30 seconds or so to stabilize the depress the bleeder on your gauge if the engine dies or stumbles real hard its more than likely a fuel pump with low fuel supply volume not pressure.

Next try reving it 1500 and repeat and look for above results then try 2500 and finally 3000. Usually idle and the 1500 rpm range will show it the worst.

When operating correctly the bleed on the pressure gauge bleeds precious little fuel from what is actually going to the injectors. However when you have a pump putting out low volume every little bit of fuel counts. I have used this on many vehicles through the years and several NNBS with cold start crank problems and found this to uncover the problem.

 

Gonzo, did you get your truck fiqured out yet??

 

it seems the issue was bad gas or a batch of heavely added winterized chemicals,thats a guess.I went back stock last Sun.,drove it while logging data,got the fuel level to 1/8th of a tank.then put in$20 0f vpower premium 92,didnt want to fill incase tank had to come out,after about 5mi I started to see fuel trims come down.filled it a couple days later,trims high but not like it was.Havent watched it since

The effects the caused was hard starting,crazy fuel trims KR at light throttle tip in or light load.Blew off the airaid intake 2xs once at TB and again at MAF,and rich codes,So going back stock im enjoying the quiet and improved mileage for now.

 

We hav **** tons driveability problems this time of year due to transition from summer gas to winter gas. They do all kinds of crazy stuff

 

I hate to tell you, but 45 psi is NOT normal under any condition. 58 is. When your problem comes back, go ahead and find an entire fuel pump assembly, because you have a check ball in yours that is getting stuck. The assemblies are expensive. I got lucky and got one from a junk yard for 100$. They were 800 new when I had this EXACT problem.

 

Please observe...these are STOCK fuel settings for a GMT900.



I don't get why people continue to take shots in the dark trying to diagnose **** after someone explains it... Don't touch the fuel system, its not broken and buying stuff to replace it would be a ******* waste of money.