update: I was able to diagnose the misfire as the cylinder 6 fuel injector, replaced it and the misfire went away. however after clearing the p0172 and 0175 code the light still comes back
I have a 2006 gmc Sierra 1500 with front disc brakes and rear drums. I have been fooling around with my brakes to get them to work right. The problem is driving down the road I can step on the pedal it goes down maybe half way, the if I let up and depress the pedal one more time it has a nice pedal that depresses maybe 1/8 of the way down. It has a new master cylinder, new drum brakes, and wheel cylinders. When I did the master I bench bled it till I saw no bubbles coming out, and did maybe 30 strokes with it not bubbling. As far as brake lines I bled those twice and I am positive all of the air is out. I also double checked that my drums are still adjusted properly after the brake job. Anyone ever had this issue before or have any Ideas on what could cause this issue?
While driving tonight I had the light go out, so when I got home I got the fuel pressure tester out. It still read 62 psi with the light out, however it only took a couple minutes in the driveway for the light to come back on. At idle I get 62 psi. With the engine off and turning the key on the gauge reads 62 psi while the pump is priming, after the pump shuts off it sits steadily at 56psi. The spec for the vin code Z engine (what I have) is 48-54 psi.
I would have to check on that. I did figure out it is fuel pump related. I have the flex fuel EFI model. It should be running at 48-52psi at the fuel rail, and mine is running at 62. Now what is special about the flex fuel model is it has no return line to the tank, The pressure is all regulated through the pump. So I could have a bad pressure sensor, or else if the regulator is bad in that case I will have to replace the pump.
I have a 2006 gmc Sierra 1500 with the flex fuel 5.3l vortec. A few weeks ago I had a check engine light turn on for p0175 (system to rich bank 2), the light turned off the next day. now about 2 weeks later it turned back on with p0172 (same code except it is bank 1). Any Idea why my truck is throwing these codes, or what it might take to repair it? Any help is appreciated, thanks.
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