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Old July 20th, 2009, 07:55 AM   #1
distant75
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Default 03 Duramax hard start

A friend of mine has a 03 Duramax with the LB7 in it with 98,000 miles. The truck is very hard to start(Cold) but will start with a shot of starting fluid. If he shuts it off will start right back up but if he waits 5 mins it wont start.

Parts that have been replaced so far:
fuel filter
glow plugs

Thanks
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Old July 20th, 2009, 08:22 AM   #2
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You need to have the balance rates of the injectors checked, and a fuel return rate test done. I suspect an injector failure. A no start/ hard start is the first sign of one going south. DON'T use ether to start that motor! Depending on the in service date, the injectors may still be under GMs special warranty (7 years 200,000 mile)
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Old July 20th, 2009, 08:27 AM   #3
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I'd check injectors and then the CP3 high pressure injection pump to make sure it's making enough pressure.
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Old July 20th, 2009, 10:02 AM   #4
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You need to have the balance rates of the injectors checked, and a fuel return rate test done. I suspect an injector failure. A no start/ hard start is the first sign of one going south. DON'T use ether to start that motor! Depending on the in service date, the injectors may still be under GMs special warranty (7 years 200,000 mile)
He said he check the balance rates with a Tech 2 at idle and they were around -.3 +/- .3. Does this sound about right?
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Old July 20th, 2009, 10:09 AM   #5
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He said he check the balance rates with a Tech 2 at idle and they were around -.3 +/- .3. Does this sound about right?
Yeah those are within spec. You may need to check rail pressure next. It could have a bad FPR or cp3. Is it loosing prime when it is a no start? Next time try pumping the primer on the fuel filter housing. I've also heard of the check valve inside of those going bad in those as well.
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Old July 20th, 2009, 01:05 PM   #6
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I'd check injectors and then the CP3 high pressure injection pump to make sure it's making enough pressure.
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Yeah those are within spec. You may need to check rail pressure next. It could have a bad FPR or cp3. Is it loosing prime when it is a no start? Next time try pumping the primer on the fuel filter housing. I've also heard of the check valve inside of those going bad in those as well.

What is cp3? i figured out FPR He also says that when he removes the fuel filter that its only about half full. On my LLY it is always at the top and spilling on things. Also when he primes the hell out of it it takes for ever as well to start.
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Old July 20th, 2009, 01:36 PM   #7
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it's the high pressure injection pump that's mounted in the front of the valley of the engine, it should produce 22-26k PSI (yes, 26,000 psi) if I remember correctly.

you might have better luck narrowing it down by searching at www.dieselplace.com because pretty much anything duramax related is there.
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