Another hard (luck) start story [Archive]

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ekw

08-02-2011, 13:20

Has anyone solved the hard start when hot problem yet?
My problem is much like many others I have read on this forum. My 2002 Duramax with 175,000 miles will start when it is cold, it will start if it sits for several hours, but if I try to start after 10 mnts or so and it is hot it will either take quite a bit of cranking or not start at all. If it does not start then it does not matter how long I wait it just cranks without doing anything. I had to use a small shot of ether to get it started this last time it happened. what is wrong?, do I have a injector leaking down and loosing prime? or could it be something else? I have had the fuel filter housing replaced already. If that was the problem it seems like the longer the truck sits the worse it would be not better. Any ideas?

My batteries are good, I even had a jump on them to make sure. the fuel filter has been changed and everything appears to be sealing. again if it was a leak problem between the tank and injector pump wouldn't it be worse the longer it sat not better?

I have been dealing with this for a while now and just want to get this truck working reliably again. Is it better to take the truck to a diesel only shop or the dealer? I live near Phoenix, AZ

Thank You.
Ernie

Kennedy

08-04-2011, 07:37

Sounds like a fuel pressure issue on the high side. More than likely it is due to excessive return volume of the injectors. At craning speed the pump just can't make the minimum pressure required to begin injection. A little sniff and it instantly accelerates and pressure rises and spray begins.

Worthwhile reading on my position regarding injector failures:

http://www.kennedydiesel.com/docs/Duramax%20Injector%20Failures.pdf

ekw

08-04-2011, 12:05

Thank you for the reply. I'm not surprised that my injectors are wearing out judging by the other posts I have read 175,000miles is not too bad. I would have to admit that I have not done anything special to protect my fuel system, just stock filter. It is however a little disappointing that the GM injectors are so expensive and hard to replace. I read your position on injector care and think you make some excellent points and I have made some mistakes. I will most likely try to do this job myself. I have been wrenching most of my life, not for a living but know my way around most tools. I am however not experienced at diesel repair. This truck is my first diesel and has been so reliable that very little has needed attention. Is the fuel injector replacement possible to do without a bunch of specialized tools? How difficult is it to remove all of the interference parts? Lastly Kennedy do you sell injectors, gaskets and piping needed for this repair? You seem to be the MAN here when it comes to parts and advice.
Again thanks for the information!!

Kennedy

08-04-2011, 12:57

Not much needed for specialized tools IF things go as planned. A good 5mm stubby hex socket is pretty much mandatory for things like rocker cover screws and return line screws. If you aren't careful you'll wallow out the return line screws so tool truck tools only here in my opinion. I have a 5mm hex swivel that also comes in handy.

The one major thing that may get you is if a sleeve comes part way up you'll have to pull it, but usually they just plain come up and that is it.

We stock Injectors, lines, return seals, thermostats, etc.

Do the thermostats while it is apart. If your rubbers are not deteriorated I'd be surprised and would like to know.

ekw

08-05-2011, 15:52

I found step by step instructions on injector replacement with lots of close up pictures. I have included the link if you care to check for accuracy. I did not know what the sleeves were so went looking. Would you agree if they don't come up with the injector that it is best just to leave them in? In general would you agree with the process that they describe in the article (if you have time to check)? After studying the pictures and instructions I believe I have the necessary skills to tackle this complicated job. When you asked about the rubbers did you mean all the rubbers or just the fuel related? the two rubber hoses that connect to the pump look a bit cracked. Not really bad but they are weathered. the cooling system rubber still looks pretty good. I am sure they are close but this truck has never been over 210 since I have owned it and that probably helps quite a bit. In fact everything under the hood still looks like new to me, no leaks, no rust, just really clean. Thanks for the input. I was just going to dump the truck and get something else. Now I think that this can be fixed,I really like the truck.

http://www.dieselbombers.com/chevy-gmc-duramax-01-04-lb7/25030-replacing-duramax-lb7-injectors-01-04-tips-hints.html

jbplock

08-05-2011, 17:21

Here's another step by step LB7 Injector replacement procedure with more detail in the member's area ..
http://www.thedieselpage.com/members/duramax/LB7InjectorReplacementc.htm

ekw

08-11-2011, 08:54

I am getting ready to tackle this project, should I get a balance test done to make sure it is injectors and which ones? What is the typical charge for this? What happens if they cannot get the truck running can they still check? It still starts when cold, most of the time.
thanks

Kennedy

08-12-2011, 06:12

IMHO, Balance rates are like taking temperature at the Dr office. They can sometimes tell if something is wrong, but more often than not in a hard start situation the issue exists proimarily at ultra low speeds (cranking) and can be masked once the engine is up to speed. Also it can be a "global" issue versus just one to three bad injectors. Not sure what the going rate is, but I would guess $80-100 based on what I have been hearing even though this is just a <15 minute task in most cases.

ekw

08-12-2011, 10:53

Thanks Kennedy.

So are you saying that a IMHO balance test is not going to pinpoint a malfunctioning injector(s)?

Is there a better way to determine if it is a injector problem and which injectors are suspect or do I have enough evidence already?

Is pinpointing faulty injector(s) that difficult and why you suggest just changing all 8 vs just the suspect injectors?

I am trying to save a little money where I can like most everyone else so I would like to cure the problem 1st time around without a lot of overkill.

Agains thank you for valued input.

Ernie

willydmax

08-13-2011, 09:21

Not trying to butt in here but last summer I replaced all 8 of the injectors, HP lines and seals on Dad's 02 3500HD and I would definitely recommend while you have everything tore down to just go ahead and replace all 8. You won't regret it. One other thing...the 5mm bolts holding the upper valve covers on are quite soft so one thing I did where possible is broke them loose using a visegrip on the outside of the bolt. I had one sleeve come out with the injector so it would be good to have some readily available from a dealer. Another thing is a good quality torque wrench. I ordered injectors, HP lines and seals from Kennedy and would recommend the same. Just my 2 cents.

ekw

08-14-2011, 19:13

Willy, thanks for your 2 cents, it really helps to know what others have done. I don't want to replace all 8 unless I need to but knowing that it is worth it in the long run makes it a little easier to spend the extra money to get it right. I don't know how long I will keep this truck but I don't want to pass a problem on to someone else. thanks again.

ekw

10-16-2011, 21:05

Anyone know where I can get OEM replacement fuel lines or?? for a 2002 HD Duamax?

thanks

Kennedy

10-19-2011, 19:03

ekw

10-20-2011, 07:43

I live just north of Phoenix and would like to pick up parts locally if possible. I went to dealer to purchase the original preformed fuel lines that lead from the filter to controller (Don't know the proper name for the silver box with the two large wire harness connections) and 1 from there to the pump supply connection. The cost was shocking, $120.00 for less than 3' of hose, come on, I passed on that! The GM part#s are 97216065, 97216604, 97216603 3163. I suppose that I could use straight fuel line and re-rout a bit, it's a pretty short distance. Anyone see a problem doing it that way? I found 8 bosh injectors here in town for a very good price, I understand that they have been in short supply lately. Don't know if that is true but that is what they told me.

ekw

10-24-2011, 08:59

I replaced my injectors over the weekend. everything went well and generally I did not have any problems. Thanks to all of the information gleaned from these forums.

I do have one concern though and could use some advise.
I started my installation on the Right side of the truck wanting to get the more difficult side out of the way first.
I had some black high temp silicon sealant which I used for the lower to upper valve cover sealant.

I went to the auto parts store needing some cleaning supplies and more silicon for the passenger side valve cover. I started reading the lables and noticed the gray high temp is also high torque presumably the stuff the factory used. So I picked up the grey and used it for the installation of the passenger side valve cover.

So my dilemma is do I remove the right side valve cover and injector supply tubes to replace the black with grey silicon? Lots of work but I would rather do it now before all the wiring and accessories are installed and 2 months from now I find it is leaking.

ekw

10-28-2011, 08:31

NutNbutGMC

10-28-2011, 15:58

Replaced all 8, filled fluids changed filters fired right up and runs like brand new, maybe better. thanks for all the advice!!! I am sure that several miss steps were avoided by all the advice and information on this site. I did end up pulling the left upper valve cover and replacing the black with ultra grey, sure glad I did.Good deal for you. I am glad you had success on the lower end of the stress level. I also think you did the right thing by replacing all 8 injectors. Historically, that has been the best decision for the good of the cause.

carco

11-24-2011, 09:10

"It is however a little disappointing that the GM injectors are so expensive and hard to replace."

Ford/IHC joint Diamond venture informed a 6.0/6.4 class that all owners should expect to replace injectors by 200,000 miles as a maintenance procedure. And they are not cheap nor particularly easy to replace. Any one replaced a fan belt on one of these engines?? whooo boy!!!