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2012 Chevy Silverado LT 1500 Z71 5.3L, 6l80, 3.42 G80 9500# tow cap.
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Discussion Starter · #1 ·
Got a question on Fuel pressure's for my Silverado. 2012 1500 LT(Z71) 5.3L (LC9), 6l80, 3.42 GU6, G80 with TOW PKG. 127,300 miles. Got the truck in January this year. Diesel was getting ridiculously expensive for my 04 F350.

COLD START KOEO 63psi. 1st thing in the morning KOER it drops to 58-59psi(normal) for approx 1 minute 10 seconds, then drops again to 42.5 to 44.1 (fluctuates). Open Loop to Closed loop??? Pressure drops 2-3psi from 42psi over 30 minutes (my understanding well within spec) Key OFF. NO Drop in performance, Gas mileage on Highway @ 60 is 22 (21.6to 22.5) avg. Running around town is about 14-15 avg. (About same as my 2013 Yukon XL I owned up to last year). I tow a 25ft (6500lb scale weight) travel trailer monthly with it and no problems.

Engine Warmed up Start. KOEO 63psi. KOER immediately drops to the 40's. This is why I'm thinking it's a Open Loop to Closed Loop thing (O2 Sensors warm up quick when cold, and it goes to closed loop).

As I'm used to seeing 50-55psi running from my 02 S-10 4.3L,(I never ran the scangauge on the Yukon) is the above cause for concern, or is it something to do with the DOD? Bad Regulator? I use a Scangauge II and monitor Volts, TransTemp, Fuel Pressure, Water Temp(stock gauge reads 210 when temp is 193-196 on Scan Gauge II.)
 

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2012 Chevy Silverado LT 1500 Z71 5.3L, 6l80, 3.42 G80 9500# tow cap.
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3 Posts
Discussion Starter · #3 ·
Old HABIT. NO CODES, Truck runs fine, starts all times ok. No stumbles, rough running.(See 1st para in Original post). I'm curious as to whether the drop to 43 or so lbs is a normal parameter or not. I'm aware the 4.3L is a different engine and setup. Return system(S-10) vs. non return(Silverado). But you'd think that somewhere along the line GM would standardize Fuel pressures in the FI engines. Maybe I'm being overly logical, and engineer's who designed these things probably never work on them. They should be REQUIRED to work in a shop for a year before hitting the engineering dept. Maybe they'd design them to make working on them Easier. Ya wish in one hand and take a cr*p in the other and see which fills up 1st.
 

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43.5 psi is the commanded pressure when running for both of your 2013 trucks. If you were to get on it and spin the motor up to WOT and the pressure dropped below 42 psi or so then you might want to keep an eye on the pump. With the right scan tool you can see the fuel trims used as the pump ages. Mine goes back and forth between the 1.40s and 1.50s and drops to 42 psi now when 5 years ago it would not. 171K miles now. Gas mileage is good.
 

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no need to worry about fuel pump or injectors unless you see codes or have performance issues. it sounds like you are bored LOL.
one thing I do know ....chevron techron additive is a GODSEND. it will prevent fuel pump failure, clean out the system, including injectors. also cleans the sending unit float. Use the techron every couple of months and you will NEVER have fuel issues. Without a doubt I would be more concerned about the lifters or AFM.
 

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But you'd think that somewhere along the line GM would standardize Fuel pressures in the FI engines. Maybe I'm being overly logical, and engineer's who designed these things probably never work on them. They should be REQUIRED to work in a shop for a year before hitting the engineering dept. Maybe they'd design them to make working on them Easier. Ya wish in one hand and take a cr*p in the other and see which fills up 1st.
The engineers of the LS are indeed car guys who drag race regularly and the same goes for many on the team who designed the 800s, 900s and K2s.

Technology advances and things change, especially government intervention which necessitated the use of cylinder deactivation so we could keep our beloved V8 engines.

I always try to discover the designer's intent before getting critical.
 
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