Duramax Diesels Forum Truck of the Week
  #1  
Old 05-12-2018, 10:54 AM
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Default 2011 LML 160mpa fuel pressure at idle?

My cousin is working on a lml that they fully rebuilt at his machine shop and installed. They also installed a new fuel pump . The truck started out without enough pressure and now after replacing the pump and regulator it now has way to much. Are the new regulators on these models prone to being bad? He said they are dirt cheap compared to the previous models .

Any ideas guys?
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Old 05-12-2018, 11:21 AM
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Check the wiring to the regulator and pressure sensor. If the regulator is unplugged or sont getting power it defaults to the full open position. If the pressure sensor is unplugged or has a broken wire, etc the ecu will read max pressure

Does it knock or run like it actually is running at 160 mpa or does it sound normal?
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Old 05-12-2018, 12:46 PM
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Check Lift pump pressure
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Old 05-12-2018, 02:25 PM
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He’s checked all that , lift pump new as well. They have had a scope on it etc no electrical issue they can find . They are pretty positive mechanical prob of some sort. Yes it has fuel knock. Can crank the truck runs fine 5-10 seconds and then defaults to 160mpa.
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Old 05-12-2018, 03:33 PM
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Make sure they don't have the plug for the fuel pressure regulator on the pump switched with the fuel temperature plug. Seen it before, usually presents as a no start though.

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Old 05-12-2018, 06:04 PM
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Ok I’ll ask them, he builds these ,6.4’s, 6.0 etc every week so he prob has them right but first time for everything. He’s ready to beat the fenders off this one lol.
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