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Old 09-06-2021, 02:38 PM   #1
not2oldchevy
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Need help with fuel pressure

53 3100 5.3 0ut of 2003 avalanche. 50 lbs fuel pressure with 3 diffrent fpr. get lean codes lt fuel trims stay maxed out 25%. Last fpr today 5olbs goes to 40s with more throttle unhook vacuum line goes to 58 lbs .Will it hurt to plug vacuum line and run it?????
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Old 09-06-2021, 06:44 PM   #2
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Re: Need help with fuel pressure

You gonna need more than 50psi...how do you have your fpr plumbed?
I'm assuming you have a inline pump and reg..
Or are you using a return rail?
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Old 09-06-2021, 07:22 PM   #3
not2oldchevy
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Re: Need help with fuel pressure

return rail new fuel lines pump and same part number filter for the avalanche
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Old 09-06-2021, 07:38 PM   #4
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Re: Need help with fuel pressure

I'm not sure on that..
Eric (ls1nova) would probably know for sure
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Old 09-09-2021, 07:17 PM   #5
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Re: Need help with fuel pressure

Quote:
Originally Posted by not2oldchevy View Post
return rail new fuel lines pump and same part number filter for the avalanche
Post a picture of the fuel rail. maybe a bad regulator. what fuel pump. maybe poor quality parts causing fuel pressure problem?

lean can also be air leaks. need to smoke test the intake to find whats leaking if anything is. intake can be cracked, vacuum port left unplugged pinched intake gaskets...

smoke test will find the leaks
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Old 09-17-2021, 10:07 PM   #6
truckdude239
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Re: Need help with fuel pressure

What pump are you running intank or inline what model? Return style system with for 9n fuel rial?
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Old 09-19-2021, 09:31 AM   #7
not2oldchevy
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Re: Need help with fuel pressure

New factory part number pump for 2003 avalanche second one. factory inline filter. return style on 03 avalanche. 3 different fpr all show 50lbs pressure. get lean codes for both sides every 5 or 6 hundred miles. put 4000 miles on it so far. unhook fuel pressure goes to 58lbs and stays. runs ok with fpr hooked up will backfire one time when you run it wfo then let off. whole fuel system is same as factory with new 3/8 fuel line. bought whole avalanche had been flipped but I drove it into garage dont know much else to tell
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Old 09-19-2021, 12:14 PM   #8
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Re: Need help with fuel pressure

Post a pic of the fuel rail, injectors and fuel pressure regulator.
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Old 09-19-2021, 12:20 PM   #9
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Re: Need help with fuel pressure

70 years old will have to find someone else do do pic it is not flex fuel and no vacuum leaks
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