Hi,
My 2001 LB7 with 202k miles has suddenly started cranking for about 5-6 seconds before starting. It never took that long before. The injectors and FPR were all replaced at 100k. It does this hot or cold, or if I wait for the glow plugs or not. The voltmeter reads about 10-11 volts during the glow plug cycle so it seems that they are drawing current. It will still take 5-6 seconds to start if you just shut it off and restart it immediately. It has not thrown a code yet, and I am worried as the weather is getting colder. It is one thing cranking a long time at 40°, but when it is -10 that will be a different story. Once it is running, everything seems normal. Any help would be appreciated.

Ed

Ok Im bringing this to the top for you because it sounds so much like my issue. I have had it into the dealer and they could find no codes, and they check the fuel system and all the pressures are good. The only thing they could come up with was that my start up cranking speed was a little low 170rpm and they said it should be over 200. The battary they said were weak and that could be it. Change them out and I still have the same issue it will crank forever before starting. The only differance i have from you is mine seems to start fair when the motor is cold. ( the temp out side has been in the mid 20ties for the last 3 weeks). When the motor is warm it just won't fire. Hope you get some help andI could use some also.

Ok so Ive done a lot of reading today and it sounds like hard starting is a common problem with injector failor. This was my first concern but the dealer told me that they were good. Is there speific questions I should ask along this line on the injectors.
I bought the truck new in 03 and it has 100,000 mile on it, the 7 yr injector warrenty will be up this comming march. It is to the point that there have been 4 or 5 times over the last 2 weeks that i didn't think it was going to fire. i know that running the starter for as long as it is taking to start this truck can not be good. Currently the dealer can not look at it again for over a week. And the last trip(5 day ago for the same reason) cost me over $500 to tell me the problem was I needed new Batterys.

03 Durmax. 100,000 miles and it just will not fire when warm seems to fire ok when cold. No fuel in the oil that I know of, no noticable smoke and once it is running it seems to run good.

These trucks use a lot of amps to start, so you do need good batteries to get a good cranking speed.

Did you replace the batteries?

Mine had been doing this for a while.I recently changed the fuel filter,and found a bad O ring on the top of the filter.(that the dealer installed)Any way it has been good to go for the last few weeks.I still don't think its perfect,but alot better.I had checked balance rates,and fuel pressure ramp up,and all was good.So I guess its worth a shot.

I did replace the batterys they were getting old so they were going to need to be replaced sometime soon. That didn't seem to help at all. The fuel filter o-ring issue seems like a good place to finish. I just had the filter changed about 2500 mile before I really started to notice the problem and felt the change might of been part of the problem. The dealer said he rechecked all of that (I told he when I dropped it off that I thought that it all kind of started after the service). So hopfully he checked this. I have pump on the primer and it seems to hold pressure so I don't know if that would rule the o-ring out. I really thank you guys for the input. hope I come across something they might not have checked.

I have found issues starting after i sent my truck to the dealer for replacement fuel filter and tranny flush under warranty. I wasn't that bad till the temps started to drop. I had started priming the filter to start since my truck would sit for a week at a time, till i had a chance to start it. This became a common occurance as the temps continued to drop and figured it to be the filter. One day i pulled it off and replaced it and whaalaah... It was done on a warm day to make sure i didn't pinch the o-rings.

My 03 with 135K miles would take longer to start than a normal Duramax. It was this way when I bought it at 123K miles. About 2 months ago I ran out of gas, for a few days it took about 6 seconds to start, then on the third day it started faster than when I bought the truck. It was this way for 2 months. Then 6 days ago I ran out of gas again :banghead: (I wasn't paying attention & my low fuel light never came on). Now it takes about 5-6 seconds to start again. Very strange.

i'd get some fuel additive and run a heavy dose and see if that helps (carbon build up will cause hard starts in diesels too) i use diesel power white bottle at 2x recommended rate and diesel kleen gray/silver bottle at 3x dose rate both at the same time cleans it up everytime

i had a very similar problem with mine but when it got below 40 degrees it wouldn't start unless it was pluged in. my o-ring on the bleeder on the fuel filter housing was bad but it didn't fix the problem. i was getting proper #'s out of the injector balance rates. it would pull 160kpa most of the time but at WOT it would drop just under. what the problem actually is, is excesive fuel return rate from the injectors. at least for mine. they have a test they can run on them and see but if it ends up not being the problem they will charge around $1000 to run the test. the only other thing i can think of is injector pump is going bad or maybe something in the tank blocking the pickup. i woulds say that evankus's problem is high return rate but gear head is probably air in the system or pump going out. really bad to run anything out of gas but diesels are the worst.

My 03 with 135K miles would take longer to start than a normal Duramax. It was this way when I bought it at 123K miles. About 2 months ago I ran out of gas, for a few days it took about 6 seconds to start, then on the third day it started faster than when I bought the truck. It was this way for 2 months. Then 6 days ago I ran out of gas again :banghead: (I wasn't paying attention & my low fuel light never came on). Now it takes about 5-6 seconds to start again. Very strange.

Try using diesel, the truck will probably run better.:HiHi:

Ha Ha you got me. I meant I ran out of fuel. This is my first diesel, give me a break.

I did replace the batterys they were getting old so they were going to need to be replaced sometime soon. That didn't seem to help at all. The fuel filter o-ring issue seems like a good place to finish. I just had the filter changed about 2500 mile before I really started to notice the problem and felt the change might of been part of the problem. The dealer said he rechecked all of that (I told he when I dropped it off that I thought that it all kind of started after the service). So hopfully he checked this. I have pump on the primer and it seems to hold pressure so I don't know if that would rule the o-ring out. I really thank you guys for the input. hope I come across something they might not have checked.

I am still betting on injectors, ball seat erosion. Engine has to crank 140 RPM or above for the computer to enable the injectors. It should start at the 170 you noted above, week battery or not. Crank time should be 2-3 seconds. 5-6 and something is wrong. If it starts fine cold, but not hot, that is what mine did. Over three months time, got worse until no start.

Bottom line, if they run the required tests under the special policy and it passes, no free injectors. You might just have to hope it gets worse faster. Drive it everywhere between now and March!

Thanks Sparky1562
Sounds like the same issue; starts when the motor is cold fine but when the motor is warm or hot it won't start worth a darn. I just hope I am around a friendly town when it finally gives up. Maybe it time to re-up my good sam club membership, and/or return one of the call to the aftermarket warrenty guys that call all day and night, but they finally quit calling-- must have know.

My service rep is a great guy and I know he will do all he can for me but as of yet his diesel mechanic hasn't found the root of the problem. I would sure just hate to get stranded with my young boys in the back country in the wrong weather without heat. Makes it kind of hard to be comfortable taking it were we like to go.

Mine would just take longer and longer to start if it was warm. Had to cool all they way down.

Still running fine on the replacements. No more special policy for me as of last october...

I would be curious to see what your fuel pressure is while cranking, if the fuel pump isn't building enough pressure, engine won't start, if is taking longer to build the needed pressure it will delay starting. I would bet on high fuel return rates making building pressure harder. Once engine is running, injector pump can overcome the high fuel return. This test can be performed with a scan tool hooked up and watching the commanded pressure vs. desired pressure while cranking.

Sparky
This week end while it was warm I had to crank it over until it timed out 5 time before it fired thisn't 7 to 8 seconds we are talking 20 to 30 second 4 or 5 time in a row. If the motor is cold it fires right up. I dont seem to have any other issue with the running of the motor. Ball and Seat erroion?- is this covered by GM or will this be comming out of my pocket?- anyone? Are there other syptom that I should be looking for when this is happening. This really sound like what is happening. Can anyone tell me why this make it hard to start and also why it is only a problem when the motor is warm. This all is new to me I have a good understanding of carborator and gas fuel injection but this Diesel thing seem much more complexe when it comes to the fuel sysem.

D. Camilleri
So based on what you wrote is it the return rate that contols the pressure or is it the pressure that controls the return rate? I am use to a gas injection system where the return rate is a bypass controled by a pressure regulator. It sounds like in this system the return rate is controls the pressure. If the return rate is high what is the cause, some fuel regulation system or the pump or maybe either?
thank again for all the help, I sure have a lot to learn.

I never got or found a good explaination as to why only when hot. My guess is that the seat expands a bit and makes the leak past the check valve worse?:confuzeld

The engine has to turn at 140 RPM, and the rail pressure has to reach 1400 PSI before the injectors will fire. Once it fires, the CP3 can overcome the ball seat erosion, putting out up to 26,000 psi.

Like Camilleri said, you need to hook it up to a scanner that can read desired versus actual rail pressure. When mine got intollerable, it would take 20 seconds plus, and almost stone cold before it would fire. Had to leave it on a job site for 5 hours before it start.

Search this site for a copy of the special policy, it has been posted many times.

Well I talked to the dealer today and they checked the injector balance and the return flow rate etc, they said and it was all good. It's going back in on wedneday, so we will see what they find. Hard to use the way it is. I cant risk shutting it off anywhere that i don't have 3 hours to let it cool down.

I am having the exact same issues as Cardiac kid. My Truck is an '02 with only 130 000 miles. My delaer spents 8 hours on it and could not figure it out. He said it is "Probably" the CP3. My truck got progressivley worse and now will not even start warm or when it is plugged in to the block heater. I found today that I can start it if I spray starting fluid into the air intake when warm. If anyone can figure his out please let us know what it is, this s driving me nuts!!!

Don't use starting fluid! your spraying it right past the intake air heater! Not good on our trucks.

Make sure your truck is fully warmed up when you take it in. Make them shut it down and wait 10-20 minutes and proved to them it will not start with the scannner hooked up. That is what I had to do. Stood in the parking lot with the diesel tech, not the service writer. Good luck.

Ok guys im gonna keep this thread going by adding another. My boss has a 03 that over the past couples months is taking longer to start then normal. His injector warrenty is up in july and has had it in twice to the dealership to check them and they both told him his injectors read fine. When you crack the bleed screw lots of fuel comes out but so does a lot of air so we bye passed the fuel filter and ran a clear hose with a outboard hand primer in its place. Primed it up but there was still air from when we hooked up the outboard primer. pumped the hand pump and cranked the truck over and it fired up after a bit kept it running and it sucked all the air towards the injection pump and we figured it would take it through the system so we kept it running for 20 mins, shut it off and slowly the air came back up in the clear tube. Truck starts a little bit better but still not good and the air in the system wont get pulled through??? Any one have any ideas, thought it might have been the filter housing but doesnt seem to be. Thanks

Thanks for the Heads up Sparky1562 on the starting fluid. I have done what you stated and the Diesel Tech at the Chevy dealership could not figure out what is wrong.

wif sensor?

my truck is an 01 3500 now with 145k its the first diesel that I ever had. I bought it with 129k and it always took a few seconds longer to start and I thought that was odd, then my starter went out, so I bought a new one and instaled it and couldn't believe how fast it started. Not realizing it was cranking too slow to fire up quickly. Anyways just thought it might be your problem as well.

Ok guys im gonna keep this thread going by adding another. My boss has a 03 that over the past couples months is taking longer to start then normal.

You didn't mention if this is when the engine is cold, or when it is hot.
From what you posted, sounds like it is getting air in the line between the tank and the filter? :confuzeld

You might try pressurizing the tank to 5 lbs and see if you get any leaks from the tank forward.

Sorry, doesnt matter if its hot or cold its the same. Im sure its past the tank though, seems to be between the filter housing and the injection pump. I am also confused as why the air between the filter housing and the injection pump wont get pulled through the system, it just sits there. Sorry still learning on these motors, more use to my old 6.5

What about the shrader valve under the black cap, near the front of the engine? Maybe it is leaking?
More likely the filter head or a hose.
Hopefully it's not the CP3!

thats for the advice sparky but could you be a little more specific where the shrader valve is and sorry not quite sure what the cp3 is either. thanks.

Add me to the list! Mine is an 02' with 101,000 miles, and according to the dealer the original injectors. I bought it with 39k on it and now I have the starts better when cold, the hotter the engine the longer the crank time!I was hoping it was the fuel filter or O-ring, but new filter and new o-ring,same problem. No codes, dealer says everything checks out OK, also informed me that my warranty is up, figures. Hope it's not injectors, but I am beginning to think it is!

Boy this thread drifted a little. For hot engines that wont start, I say have the starter tested.

I found today that I can start it if I spray starting fluid into the air intake when warm. If anyone can figure his out please let us know what it is, this s driving me nuts!!!
Sounds like you have a Detroit in it!!!

You didn't mention if this is when the engine is cold, or when it is hot.
From what you posted, sounds like it is getting air in the line between the tank and the filter? :confuzeld

You might try pressurizing the tank to 5 lbs and see if you get any leaks from the tank forward.


If you had a lift pump would that have enough psi to do the same? I had a leak and the lift pump was pushing fuel out the bleeder screw with the engine not running.

it has nothing to do with the starter, the dealer tested the crank speed, it is fuel related.

Cardiac Kid, do you have a Juice with attitude programmer by any chance?? I do and I have had nothing but problems since i put it in my Truck (currently removed). I noticed that minisrule has one and he is having this similar problem.

thats for the advice sparky but could you be a little more specific where the shrader valve is and sorry not quite sure what the cp3 is either. thanks.

At the front of the engine, toward the passenger side, there is little black screw cap. Under the cap is a shrader valve that is used to check the vacuum after the fuel filter and before the injection pump or CP3.

Just grasping at straws. More likely the filter head or a hose from what you posted, IMHO.

Thanks for the info sparky, we will take a look at those on monday.

Cardiac Kid, do you have a Juice with attitude programmer by any chance?? I do and I have had nothing but problems since i put it in my Truck (currently removed). I noticed that minisrule has one and he is having this similar problem.

No i don't have a juice. I took my truck to a different dealer by the suggestion of my normal dealer. He suggested it because he knows the tech there and said the guy is really good and his tech couldn't find any thing wrong. The new dealer's Tech is telling me it is the injector pump so I am waiting for them to get it in on Monday and installed Monday or Tuesday. I will let you know if it works or if they are just trying things out on my money.

Well I got the truck back with the new injector pump and it is 98 % better. It still cranks a couple of times more when warm than when cold but it isn't like it isn't going to start. I would say there is still a minor issue going on but i can at least fell comfortable driving it and don't have to worrey about being stranded somewhere.

How much did the dealer charge you for the pump and to install it ??

jmarcink
pm me and I will share

im in the same boat as everyone here. i put new reman injectors in 4500 miles ago because of excessive smoke and rough idle. now truck starts fine when cold but when its warm there is no starting it. if it does start it cranks for about 20 seconds first. i've ruled out my cp3 and FPRV so im leaning towards high return on injectors. there are kits on ebay for 75.00 include 4 viles and lines with fittings. from what i have read you test each bank off the cylinder heads where the return lines come out from, to see which bank has the bad injector. unplug FICM or pull out ign fuse and crank for 15 second to fill viles. then from there have to tear into it and remove valve covers and test each injector seperatly with the viles to see which one has the high return.
only information im still searching for is the amount of fuel that should fill the vile after the 15 second crank. how much is to much and how much is normal...?
there is no way to check return from each injector with a tech 2?

no way to check from a computer that i have ever heard of. as for what comes out of the injectors....i would say that there probably isn't an exact number but that you are looking for the odd one out. just a guess though.

alrighty. what im not sure of though is when i test the left and right side banks, if i have a bad injector on both sides then im gonna show a similar amount of fuel in each vile. i wont know if that amount is normal or to much, know what i mean..? so at the very beggining im gonna need a number to work with i think. after that once i test each one seperatly it will probably be obvious which is putting out to much fuel...

i had read a post on here about a year ago that had some info on it but i have no idea where it was. you may do a search on excesive return rate test or something along those lines.

Yet another story . Was having the same hard start when hot problem everyone is talking about . Took it to a lacal diesel tech first to get an idea what was going on. He is pretty sure it's the Cp3 pump. Truck also had a po380 glow plug code . Took it to the dealer to get the glow plugs fixed under warranty and had them check for the hard start . They check the flow rates ,return rates etc. The tell me the Cp3 is bad. Have them go ahead and replace. Get a call from them , some good news and some bad news . After replacing the pump it starts better but not great . They do another return rate test and sure enough it's too high. They figure it didn't show up the first time is because the pump was not strong enough . Now my special policy timed out last Oct.. The dealer knows this but calls GM anyway. The good part , GM says to go ahead and replace injectors under special policy. Don't ask how because I have no idea. I would say the dealer REALLY came through for me. Truck should be ready early next week , I'll post a follow up. It seems to me that the Cp3 and injectors are so interdependent on each other that it's very hard to determine if it's one or both causing a problem. In my case I suspect that the injectors were retuning too much fuel first ( no crankcase fuel) and overworked the pump . When the pump got weak enough it couldn't compensate for the high return rate and wouldn't start.

i think your getting your chain yanked because it won't have good return rate with a bad pump and then bad return rate with a good pump. the numbers would have been off somewhere and they probably should have replaced the injectors first. that is probably the only reason they are covering it just because it was there mistake to begin with. just my thought on the matter, not like it matters much because it seem like it is working out pretty well for both parties.

I had the same thought at first. The thing is I was going to take the truck from the dealer and it wouldn't start at all so I left it. With the new pump it starts but not as soon as it should so the pump made a difference. Since I was not present for the work I'll never know for sure. They said initionally the return rates were within spec , I think a weak pump could possibly give that result. With the new pump the return rates were out of spec. You still may be right . I wasn't in a position to tell the dealer to change the injectors since they were out of warranty unless I wanted to pay for them.

i have a 2003 duramax just one day out of the blue . i had a hard start problem. wouldnt throw no codes no nothen, no fuel leaks went on for about 2 weeks. one day, ended up getting a code turned out to be a crank sensor, starts fine now.

my truck has been a little difficult to start when its cold out and i think it might be the glow plugs. if you have a bad glow plug will it throw a code?

i looked at this link http://www.dieselplace.com/forum/showthread.php?t=297996&highlight=glow+plugs

and it looks like my truck falls under this warranty. should i take it in? my injector warranty is up in a month or so. maybe they will do a balance rate check for free?

update on my hard start issue; i did a return test on mine this weekend and i had an injector on driver side that was putting out 3-4x what its suppose to. and when the engine was warm it was more to the point where the pass. side wasnt hardly putting out any fuel at all because it was all going out the one on the driver side. so im guessing this is my problem and i order a single injector and we'll see what happens..

update on my hard starting, They replaced the injector pump and as I stated it was 95%better it started fair and would alway start witin 5 seconds, but it wasn't 100 percent I could tell. Well it quckly deterated and was back to starting poorly when the motor was warm within 2 weeks. Took ti back in and it took mutiple test runs but they finally got the injectors to not pass. The tech said he thought it as the injectors the first time but he could never get a failing test and the only thing he could find was the low rail pressure. Now with the injectors replaced it fires right up like it should. So some how there is some interreaction here because the new injector pump did make a big differance but the injectors were the underlying problem.

update on my hard starting, They replaced the injector pump and as I stated it was 95%better it started fair and would alway start witin 5 seconds, but it wasn't 100 percent I could tell. Well it quckly deterated and was back to starting poorly when the motor was warm within 2 weeks. Took ti back in and it took mutiple test runs but they finally got the injectors to not pass. The tech said he thought it as the injectors the first time but he could never get a failing test and the only thing he could find was the low rail pressure. Now with the injectors replaced it fires right up like it should. So some how there is some interreaction here because the new injector pump did make a big differance but the injectors were the underlying problem.

That mirrors my experience.

I'm having the EXACT problem as cardiac kid and the others. have been on other forums, but thankfully just found this one. Truck has stranded me and my family several times over the past months by not starting once warm and we have stopped driving it until I can feel good about the diagnosis. Dealer sounded like they had a hell of a time and finally settled on a defective injector pump leading to low rail pressure when warm. They said they ruled out injector problem simply by no fuel in oil. Should this be trusted? Cardiac Kid, were your injectors covered? What did the pump run you? Any info by anyone would be appreciated before I proceed further. Thanks!

Under the special policy, they have to run specific tests to rule out injectors. Just because there is no fuel in the oil does not mean it is not the injectors. They fail in two ways, cracked housings and ball seat erosion.
They want you to replace the CP3 because it is not warranteed! find another dealer.
Special policy is 7yrs from in service date or 200 K miles.

Fill out your signature so we know what you have and mods!

sparky1562, do you knwo what causes the high return rates on injectors? i replaced mine 4k ago, 8 remans, and i just recently had to replace 2 of them because the return rates were unbeleiavble. no fuel in oil, no smoke, just hard starting... what causes the high return anyone know?

Thanks for the info. Just find a new dealer and say I want the injectors tested? I'm in Maine, anyone have a recommendation? The no warm start is a symptom of the injector problem correct?

The no warm start is a symptom of the injector problem correct?

yes

sparky1562, do you knwo what causes the high return rates on injectors? i replaced mine 4k ago, 8 remans, and i just recently had to replace 2 of them because the return rates were unbeleiavble. no fuel in oil, no smoke, just hard starting... what causes the high return anyone know?

Ball seat erosion. To much fuel returning to the tank, rail pressure can't build fast enough or at all. Has to get to 1400 PSI for the injectors to fire. I have never read a detailed explanation on why it happans when hot, but i assume expansion in the injector due to heat makes it worse.

So how do you check the Return Rates? On the Tech II all we seen that was close was Circulated Fuel Rate 10 mm3 . Right now the truck is hard starting when hot. When we did test it with the Tech II of course we could not get it to hard start ( Of Course )

It had one error code P1621

Truck Warmed Up

Actual Fuel Rail Pressure 5046
FRP 1790 mm3
Circulated Fuel Rate 10 mm3

In Park / In Drive
1 / -.9 / -1.3
2 / .0 / .3
3 / -.5 / -.6
4 / -.2 / -.1
5 / -.2 / -.1
6 / -.5 / -1.2
7 / -.8 / -1.2
8 / 2.9 / 3.7

So how do you check the Return Rates? On the Tech II all we seen that was close was Circulated Fuel Rate 10 mm3 . Right now the truck is hard starting when hot. When we did test it with the Tech II of course we could not get it to hard start ( Of Course )

It had one error code P1621

Truck Warmed Up

Actual Fuel Rail Pressure 5046
FRP 1790 mm3
Circulated Fuel Rate 10 mm3

In Park / In Drive
1 / -.9 / -1.3
2 / .0 / .3
3 / -.5 / -.6
4 / -.2 / -.1
5 / -.2 / -.1
6 / -.5 / -1.2
7 / -.8 / -1.2
8 / 2.9 / 3.7

you have to buy a fuel return test kit. its sort of like a chemistry kit! lol it has 4 viles to measure the fuel, and 6 hoses with the correct fittings. two for the fuel return rails on each head so you can measure the return from each bank. then 4 hoses for the injectors, so you can measure each injector on one bank. they retail for a rediculous amount of money, something like $300.00 i think. but i got mine off ebay for $75.00

OK Thanks I was under the impression the Tech II checked the return rates