LMM Headache

ovnttim

New member
Nov 28, 2014
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I will get right to the point. 2007.5 GMC Sierra 2500hd LMM. Started out with a slight tick l took it as a injector. 125,000 miles on it. Ticking noise would come and go. Ran fine no codes then I got a Reduced Engine Power. I put new fuel lines on from engine to the cooler to the fuel tank. Thinking maybe a kink in the fuel lines. Since then I’ve changed fuel filter head (new) fuel filter, all rubber fuel lines for the fuel filter housing, cp3 rubber lines, new FPR. Truck cranks over great but won’t start. Scanner showing fuel rail pressure 7000 to 8500 psi at cranking still no start and no smoke at exhaust. If I had a couple of injectors go bad would that cause a no start and no smoke coming from the exhaust. Thanks for any help
 

ovnttim

New member
Nov 28, 2014
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No codes no blown fuses. Scanner shows crank/cam yes when I’m cranking the engine also shows my rpm. I figured if it’s showing my rpm while cranking crank sensors would be ok
 

08lmm72mm

Active member
May 13, 2019
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Saskatchewan, Canada
Check the pins in the main harnesses on top of the drivers side valve cover where they connect together. Couple might be pushed in and they will cause a no start condition.
 

ovnttim

New member
Nov 28, 2014
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Checked the pins they all look good. I thought maybe it was getting air though my fuel lines so I’ve disconnected those lines and have two clear lines connected to the engine and put in a five gallon diesel container. I can pump filter primer top and get a solid feel. While cranking I don’t see any fuel being drawn in.
 

JoshH

Daggum farm truck
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Feb 14, 2007
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Texas!!!
I just went through a similar problem on an LMM here at the shop. It ended up being a spun crank reluctor causing a cam/crank sync error. No codes and both sensors showed yes on a scan tool.
 
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ovnttim

New member
Nov 28, 2014
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That’s my next check. I’ve read about that. Just not sure how to check. Is there a way I can check the reluctor plate
 

ovnttim

New member
Nov 28, 2014
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I just went through a similar problem on an LMM here at the shop. It ended up being a spun crank reluctor causing a cam/crank sync error. No codes and both sensors showed yes on a scan tool.
That’s my next check. I’ve read about that happening. Do you know how I can check it.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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That’s my next check. I’ve read about that. Just not sure how to check. Is there a way I can check the reluctor plate
to check if its loose, you can usually snake a little screw driver in the hole the crank sensor goes in and see if its loose but to see if its spun, you either need a scope on the sensors to watch for the cam crank corrilation or pull the front cover and inspect it.
 
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