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Discussion Starter #1
Hey guys I just cant seem to find the solution to my problem. I have a 2006 colorado that had a 3.5 in it that I have swaped to a 5.3 I did the harness my self as well as the exhaust and other misc stuff. The 5.3 is. 99 as well as the pcm that I had programmed, I have a couple issues but the biggest is function asthe truck runs and drives but falls flat on its face at wot or basically anything above 1/4 throttle while driving. When I first got it running last year it had the stock colorado pump and ran ok, then the pump fryed switched to a 255lph pump and runs the same thought maybe it was a tuning problem and had .y spare pc. Tuned by a different place with a completely stock tune minus vats and basic emmisions and still no change
Iv been fighting with this for a year and any help would be great
 

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US Army 19yrs and ......
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Are you running a return style fuel system......if not, do you have a fuel pressure regulator?
 

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Discussion Starter #3
I am running a return line and I have replaced the regulater, also replaced the cam sensor and put a new maf on it when I got the motor
 

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maniac mechanic
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It's hard to say without logs of what is actually making it fall on it's face. See if you can find someone with HPTuners and log the issue and post it up so I can look through the log and see what seems off.

Just one simple check you can do to rule out the fuel pump. Hook up a fuel pressure gauge and ziptie it to the windshield wiper so you can go for a drive and watch it. If the fuel pressure drops off when you hit the throttle past the problem point then you have either an electrical or mechanical issue with the pump. If fuel pressure is fine then you need to look to the rest of the sensors and programming.
 

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what do you have the fuel press set at ? idle ? wot ?
 

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Discussion Starter #7
The fuel pressure is at 58 psi via the stock fpr at idle I have not checked it while driving yet cuz I dont have a guage that is long enough to see. Is it possible that the stock fuel lines are to small?
 

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Discussion Starter #9
ok guys I have an update, all my pressures are good. I was messing around today and put the truck into first instead of drive and had no issues it took off like a rocket, I didn't take it down the road and manually shift it up to d yet but im wondering if not having the tcc brake switch wire hooked up could have been causing my problem all along. also does anybody have the pinout for the bcm so I can hook up the serial data from the 5.3 pcm to it?
 

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hmm maybe it is just something as simple as the shift tables being off? I'm pretty sure you lock them out when you select the gear. It could be some sort of transmission safety mode which is reducing the trans output since it senses somethings wrong with the programming.
 

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Freak, what are the Scangauge numbers for fuel press ?
 

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Discussion Starter #13
im making progress to some degree, I have drove it some and gotten the gauges half working but I still have a dead spot so im thinking about just dropping a new tps sensor on it now that my tac works. im idling at 550 to 600 so im thinking it may be part of my issue. thanks for all the help so far guys.
 
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