low fuel rail pressure - Diesel Bombers



Chevy/GMC Duramax 04.5-05 LLY Discussion of Chevy and GMC Trucks with LLY Duramax Turbo Diesel Engines

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Old 09-08-2012, 05:10 PM
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Default low fuel rail pressure

I got a 05 duramax won't start with out either took. It to dealer said 1,6,7,8 injectors were bad replaced them put new fuel pressure regulator on and injector return lines because I had a leak efi says I have 230 psi in my fuel rail any suggestions?
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Old 09-09-2012, 12:13 AM
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turning over fast enough?
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Old 09-09-2012, 10:27 AM
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Turns over fine
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Old 09-09-2012, 11:07 AM
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bad cp3
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Old 09-09-2012, 12:19 PM
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Yes turning over fine
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Old 10-27-2012, 01:29 AM
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I agree: bad cp3. You need an injection pump, buddy. didn't they up the rail pressure with a scan tool to see if it held? You should always do that after replacing injectors. If the balance rates are all good, with new injectors, it should hold 160 MPa. If it doesn't, suspect the injection pump.
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Old 10-27-2012, 11:13 AM
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Don't waste the money on a cp3! It will not fix your problem. When the cp3 pumps take a **** the readings are much lower. First check your oil for any fuel smell. You are looking for another bad injector. If the oil smells fine you need to pull the valve covers and carefully inspect all the injectors for any obvious defects. I just had a duramax in my shop with the same issue. The man had just taken it to another shop that told them the cp3 was bad. They replaced it and still got the exact 230psi fuel pressure reading. I got no codes with the scan tool. After beating my head against the wall I decided to pull the valve covers and simply do a visible inspection. I found that one of the injectors (#2) was actually broken right at the electrical connector. The wiring to the connector was still intact but it was allowing a fuel leak. Enough so it could not build enough pressure during cranking. You simply don't want to overlook this and end up wasting money on a cp3. PS..... NEVER USE EITHER ON A DIESEL!!!! At the very least it can melt glow plugs witch reach a temp of over 1300 degrees in less than 4 seconds. If that happens you end up tearing the engine apart to get the broken pieces out after you remove the damaged glow plugs. You should always disable the glow plug system then go to your local napa or what ever auto parts place and get a can of SILICONE SPRAY. It will start off of silicone spray and it lubricates so you don't have to worry about it washing down cylinder walls and creating a ring problem like you can commonly find with either. Good luck
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Old 10-27-2012, 04:26 PM
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Silicon spray?!, I have always heard To use WD-40
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Old 10-27-2012, 05:18 PM
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Yep, silicone spray. It starts off of it just fine and doesn't damage the engine. That is all my shop uses on diesels.
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Old 11-05-2012, 05:23 PM
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help
along the same lines, i`ve replaced the filter housing bout 12 k back, just changed fuel filter, shimed the frpr valve twice, no fuel in oil, whats next?
have 96k on truck 04.5 lly

---AutoMerged DoublePost---

well took it to chevy, they said injection pump 96k on this truck
any suggestions as far as parts, or kits or?
thx

Last edited by aj43az; 11-05-2012 at 05:23 PM. Reason: Automerged Doublepost
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