2003 Duramax will not start engine is hot without prime.
 

Having trouble restarting my 2003 Duramax when it has warmed up for 10 minutes or more.

Symptoms:


No codes

Starts cold with in seconds
Runs great
No smoke
No loss of power
No fuel in crankcase oil
Replaced fuel filter with in 100 miles
Replaced fuel filter/primer pump with in 100 miles
Will start when engine is hot after depressing primer pump 4 or 5 times (until firm)

Wife ran truck out of fuel 500 miles ago

Altinator went bad 600 miles ago.

Replaced one battery 450 miles ago

Any Ideas anyone

sounds like a bad cp3

My ignorance
What is a CP3?

the injector pump

Thanks for the suggestion.

How do you check out the CP3 Fuel pump regulator?

Engine idles fine

ECM lost VIN after altenator went bad and truck almost shut down when batteries went dead.

Replaced ECM

do you have a rail pressure guage

Ran the fuel pressure up with the computer.

Pressure did not drop off.

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Ned to get one.

the lift pump pressure or cp3 pressure

Don't know which pressure they were showing me at the GMC shop on the computer.

My curosity is why does the truck start great in the morning when the engine is cold and just crank over when it is hot?

i had a ford idi 7.3 that when it was cold would fire right up then when it got hot it would not start unless i used some kind of starting agent
when your wife ran it out of fuel your injector pump was ran dry no lube means alot of wear real quick and i think that is your issue

Ouch

I will start there

Thanks for the suggestions Hot cummings

no problem bro good luck with it

check and make sure the fuel filter is on there good and the bleeder screw is alright.

Here is a link to fuel system diagnosis.

https://www.dieselbombers.com/chevy-...odes-tsbs.html

sounds like a good possibility of injectors or cp3 ....

wierd! i dont think it could be the bleeder screw cause if it was then when it sat over night it would loose prime, i also dont see how it could be the injectors, could be the FPR or CP3 tho,

Sure it's not just a bad seal at the fuel filter somewhere causing it to lose prime?

if it loses prime when its warm its still gonna lose prime when its cold!!!!:tu:

unplug you fpr and see if that makes a difference, or have some one w/ a tech 2 go in and read what your fpr and cp3 are doin,

i have almost same problem but my truck loose prime when it is really hot weather (80 F +). or maybe summer blend diesel. i have no problem when its winter. mostly i have to prime it when the diesel tank is on at least 3/4 tank or less....this first happen when stealership changed my fuel filter and i have replaced filter many times now and still happen. the dealer checked everything fuel pressure, codes, etc....and they are functioning normal. please help and thanks in advance...... i am considering putting on airdog fp100 to maintain the pressure on my fuel line....:c:

same problem
 

Did you ever figure out this problem? I have the same problem. My trucks at the shop now:humm:

Had same problem with mine 100+ degrees would run about two minutes then act like it lost prime. Reprime get another two minutes. Put a bag of ice on fuel controller made it 300 miles home. Crazy!

Had a buddy of mine take the fuel primer apart and replaced the gaskets inside and replaced the fuel filter. So far so good, but it hasn't been 100 deg. + outside either. Keep you posted :)