Hard start problem with stock 2006

Yesterday my 2006 5.9 didn’t want to start. It is stock except for HPP EFI Live tunes that have been on it for probably a year or more. The truck would turn over for around 5 seconds and then finally crank. Once running, it initially seemed to run normally. I made some short trips during the day with no issue other than slow starting. Then later in the day, after about an hour on the interstate at 77-78mph it almost felt like it died. I had my cruise set and it just lost all power for about 1 second and then came right back on and maintained the same speed on cruise. The chime did ding though and the check engine light came on. It continued to run fine for about another 20 miles until I reached home. At home I tried to see what code it set with my V2 but despite still having the check engine light on, it said no DTC’s. I cleared the codes and the check engine light went off. The truck would then start but it was still slow to start. I revved the truck a little in neutral and the RPMs climbed on their own to 3K and hung there for a few seconds before returning back to a normal idle. There hasn’t been any white smoke or rough idling. I did notice a little black haze at an idle though the other day that I hadn’t noticed before. The truck has 140K miles. Any ideas? Thanks for any help or info.


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Sounds like injectors.

Yup sounds like injectors. But a person should check the limit valve as well.

Can you view commanded vs actual rail pressure? also do you have a way to view supply pressure to the cp3 pump? Factory in tank lift pump or aftermarket? There is some other things that you can check that take more time or you can just assume injectors and replace them before the motor is damaged. That is what I would do If I was still running stock injectors.

Thanks for the info everybody. I have a EFI Live V2 so I suppose I could data log commanded vs actual rail? I may be wrong though. I’ve never even data logged before, and I currently have no gauges other than the stock cluster. I haven’t put gauges in it yet because it is currently totally stock other than EFI Live tunes from Jonathan at HPP. The in tank lift pump is stock and seems to be working appropriately. I haven’t checked the fuel pressure to the CP3 though. The factory lift pump does turn on and pressurize the line when I turn the key on. If I bump the key it turns on again. So it seems like it is working normally. I am the fourth owner of the truck and as far as I know the injectors are the original stock injectors. I figured it might be injectors also. Is there any way to check the injectors without removing them? Thanks again for your time and help.


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The test procedure is to run the truck at 1200rpm and 20,000psi rail pressure and measure return flow from the back of the head. Max spec is 160ml in 30 second test.

Might be a good idea to take the truck somewhere that has the correct tools and scan tool to check injector leakage. It can be done, but to do it right you would want to buy the special banjos to isolate the injector and pump return, as well as a graduate to measure the return quantity. Another option if someone in your area offers it would be to pull the injectors and have them tested.
There is some decent info here too.
Dodge Diesel Diagnostics | Oregon Fuel Injection

If you do the tests yourself, collect multiple samples (3) and average the results.



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Thanks for the good info. Probably going to take the truck to a local diesel shop but wanted this info to help guide them/make sure they were headed in the right direction. I will update the thread when i get it figured out/fixed. Thanks again


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You may try plugging the rail relief valve and see if that helps. I usually try everything possible before pulling the injectors because its so expensive to have them tested.

SPEEDSHIFT said:

You may try plugging the rail relief valve and see if that helps. I usually try everything possible before pulling the injectors because its so expensive to have them tested.

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Sounds good. Definitely don’t want to pull them if I don’t have to. Thank you


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i would have to agree. buy a rail plug and i would also make sure the pump is keeping up. your EFI live can log all of this at once, just select EDA on the bottom lost of PID's.

its about time for your sticks to go out with that mileage but i wouldn't rule out the Cp3 either...

in my experience, if its injectors, you can free rev the engine up to 3k or so and you will hear fluttering in the motor when it is decelerating back to idle.

Thanks for the input guys. I have an update. I’m not sure the problem has been fixed because a definite source hasn’t been identified yet. That being said, the slow starting problem got progressively worse and began to sound more and more like weak batteries, a weak starter or bad cables. I removed the batteries and had them checked, and they checked out fine. I tried charging them anyway and checked all the battery cables. All looked good. It the truck would barely start. I replaced the started and now the truck starts great, better than any other time the whole year I’ve owned it. I also replaced the fuel filter. I’ve only put 100-150 miles on it since these changes, but so far so good. It may return though at any time. I’m going to just drive it for now and see. Injectors were my first thought too because of the year model and current mileage. I am the fourth owner of the truck though and it’s possible the injectors were replaced before I bought it with 120K miles on it. I don’t know for sure. I’ll update the thread if/when it acts up again and try looking at the relief valve, injectors and CP3 as suggested. I’ll also data log with my V2. Thanks again for all the good information.

I also took the truck to two reputable local diesel shops and they couldn’t find anything wrong with it. Not sure what all they checked. I think they checked for codes and when it didn’t have any they gave up. I know they didn’t check the return on the injectors or check the rail relief valve. Anyway, I’m going to drive it daily until it acts up. Thanks again.

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A hard voltage drop (like a worn out, shorting starter winding) can kill voltage to the rest of the truck and make the ECM go haywire.
Disconnecting the batteries and having them tested probably reset the ECM, then changing the starter fixed the starting issue.

Even so, with that many miles, be prepared for injectors and/or CP3 to start failing.
The hanging throttle is a warning sign on injector condition.

My final concern is the momentary cut out at 77-78 MPH, which is not normal and could be a sign of an ECM failing, loose connection(s), or bare wiring grounding out somewhere.

Mark.

Sounds good Mark. I’ll keep that in mind. I’ll update the thread if it acts up again and I get it figured out. Thanks again for the good info


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