2003 Duramax won't start when hot. - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 6 (permalink) Old 05-12-2012, 10:35 AM Thread Starter
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2003 Duramax won't start when hot.

I have a 2003 2500 HD that will not start when hot. It starts fine when cold and runs great. No smoke and plenty of power. Once the engine heats up if you shut it down it won't start for at least 2 hours until completely cooled off.

I have taken it to the GM dealer who tested it and said it might be the injectors but he wasn't sure as they all tested fine. He couldn't find the problem. The only thing he did was replace the pressure release screw on top of the fuel filter housing. That seemed to help a little for a short period of time.

I have replaced the fuel filter (GM produce) five times in less than 100,000 miles so I don't believe that is the problem.

Any ideas how to fix this problem?

Thank you!

Last edited by Bhenriksen; 05-12-2012 at 11:49 AM.
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post #2 of 6 (permalink) Old 05-12-2012, 10:52 AM
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Have the return rates on the injectors checked. I heard this has been other peoples problems.

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post #3 of 6 (permalink) Old 05-12-2012, 11:47 AM Thread Starter
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If the return rates are off does that mean new injectors?

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post #4 of 6 (permalink) Old 05-12-2012, 12:46 PM
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I would say injectors returning too much fuel is a good possibility also. Do the bottle test when warm, and try a good injector cleaning. There are excellent writeups here about both.

Need LB7 Injectors? Check these prices out!

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post #5 of 6 (permalink) Old 05-12-2012, 01:27 PM
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Common problem with bad injectors on the LB7 engine. When the engine is warm, they by-pass to much fuel, and the rail pressure is low.

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post #6 of 6 (permalink) Old 05-13-2012, 01:23 PM Thread Starter
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If a fuel pump was installed would it bring the rail pressure up so it would start?
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