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2003, Duramax LB7 The engine was running before i started the project. I had fuel getting in the oil. So i replaced the injectors. Replaced the Fuel filter. When i pump to prime i got all the air out i think. Takes about 3 - ... JOIN NOW TO REMOVE TRACER

Replaced Injectors, need help

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Old 09-11-2013, 02:21 AM

Default Replaced Injectors, need help

2003, Duramax LB7

The engine was running before i started the project. I had fuel getting in the oil. So i replaced the injectors. Replaced the Fuel filter.

When i pump to prime i got all the air out i think. Takes about 3 - 5 pumps to get stiff.
Now it just rolls over and never fires off.

Any thoughts would be greatly appreciated.

---AutoMerged DoublePost---

Another queston:

When priming this LB7 , should it prime the common rail to the injectors ?

Last edited by mstrbuilder; 09-11-2013 at 02:21 AM. Reason: Automerged Doublepost
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Old 09-11-2013, 11:39 PM
Diesel Fan


How long did you crank on it? It really helps to have some one pumping the primer while you are cranking.
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Old 09-12-2013, 08:42 AM


Yesterday, after letting it sit awhile i noticed a small amount of fuel acumulated on the filter housing. I assumed that was a leak in the housing. ( just put all new o rings in it a month ago). So I replaced the housing. I will have a friend help pump. I've have cranked on it for about 5 seconds at a time.
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Old 09-12-2013, 06:11 PM
Diesel Fan


You may have to crank longer than 5 seconds but having help priming it will really help. FYI, once the truck fires up there will be a fair amount of white smoke but will clear out once you take it for a test drive.
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Old 09-13-2013, 06:00 PM


I cranked on this thing on and off for about 10 minutes , got a little white smoke but did not get it to start up. Charged up the batteries and cranked again for about 10 min, stioll no start.
while cranking can i loosen one of the nuts holding the injctor lines onto the common rail to see if fuel is actually getting past the cp3 ?
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Old 09-14-2013, 01:17 AM
Diesel Fan


On passengerside front of motor there is a fitting that looks like an ac hook up it will bleed off the rail assembly. Any way I had to bleed the fuel here , close it up,then pump prime while my wife cranked it over for 30 sec or so. Fired up then died 10 sec later. Repeated and started up fine. Two things also check wif sensor for leaks. I blew mine off the bottom fuel filter by pumping too hard. Also bleed screw on top make sure its in good repair. Ive read about people having issues with quick connects at tank leaking after priming. Seemed they just popped back together. Did you do injectors youself where did u get from? Mine in my 04 are gone!!! And will be needing some in short order.
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Old 09-15-2013, 04:50 AM
BigMatt's Avatar


Did you replace the bleed screw rubber o-ring? If you didn't replace it. That may count for the fuel you see on top of that housing. I had and issue with mine when I replace my fuel filter. Good Luck!!!
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Old 09-15-2013, 02:41 PM
Diesel Bomber


I have always had luck pouring a small cap full of gasoline into the intake to act as starting fluid. After priming it will fire off the first time. It takes about 5-10 seconds of cranking to pull the air and gas mix into the engine. I pull the maf sensor out and pour about a cap full in the opening. It may not be recommended but it is safer then starting fluid.

Also, try replacing the short hose coming out of the filter with a clear one to see if you are getting bubbles/air in the fuel.

2004LB7's Sig:2008 LMM Duramax 3500HD Dually
EFI Live, 5" straight pipe exhaust, 285/75/17 Nitto Dura Grapplers
4-6 Cognito lift, 4.56 gears. Rapter 160 lift pump, TransGo Jr.

Last edited by 2004LB7; 09-15-2013 at 02:44 PM.
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