Hard Starting

[CPence]

I posted a starting problem back on 1-17-2011. I had a lot of good input and do appreciate that. I thought that I had it fixed but now am right back to square one.

My 03 3500 would not start after sitting 2 weeks, no OBD codes showed. So I installed a new FASS fuel Pump and pressure gauge, it ran but started slow (spins over fast but cranks a long time 10-15 seconds) 15 lbs fuel pressure. I installed a new Fuel Control Actuator, and again it ran good once it started, plenty of smooth power, this time it was OK for about two weeks. It sat all day yesterday and would not start yesterday evening. I cranked longer than I should have but no start. I plugged the block heater in for two hours this morning, still no start. I went by the local repair shop that works on Dodge Cimmins (the two owners also drive Dodge Cummins Pickups)and have a good reputaion. They have two customers 2003 Dodge Cummins in their yard that they have been working on with the same problem and they do not have an answer. They tightened the fuel injector in put lines on one of them and it seemed to help some. I have a feeling that my high pressure is bleeding off while it sits but do not know where to look for for a valve if there is one that might be allowing bleed off. Any suggestions will be appreciated.

 

[CPence]

I have problems believing that my problems are injectors because in runs so smooth, and no other problems once it starts.

I adapted a high pressure gauge to the common rail by removing the high pressure relief valve on top of the common rail yesterday, and as soon as the pressure in the common rail reached 5,000 lbs it started (now for two days it would not start,I tried everything I could think of except starting fluid). It had a high pressure of 15,000 Lbs and idled at 11,000 Lbs.

The high Pressure relief valve lets fuel out at 15,000 Lbs. Since removing the HPRV and putting it back on, the pickup is starting just like it used to.

I am absolutly stumped.

 

[cerberusiam]

Cpence, you need to run and injector return flow test to verify. The injectors will run good and show no signs of problems but if the internals are worn and bypassing too much fuel, no start. Probably need to check your CP-3 return flow also to rule it out.

 

[TCDiesel]

CR injection systems are so tight ,replaced components that are lower then 100% will solve the problem for a short time... I have stated this Many times "CR does NOT conform to logic it conforms to experience".

 

[cerberusiam]

Its Injectors... . The CP3 has NO options. .

Eh?





Not sure WHAT you are saying but the CP-3 has return flow specs and circuits. The COV is designed to feed the rail first and lube\return second, but, if it fails to function correctly the high return rates will have an impact on rail pressure at cranking.



Doesn't happen often but it is a possibility.

 

[TCDiesel]

I give up... . Its getting to the point of removing My membership form the TDR... EVERY TIME SOME OTHER MEMBER POST THEIR INPUT ITS QUESTION BY YOU... His problem obviously by the remotest possibly may be related to the pump... how many CP3s to you break down daily? I'm tired of the intellectual exorcises you put members through... "flow specs and circuits" Now I will put you through the intellect,What are the flow specs? what are the circuits? and how and the heck is the OP going to perform these on the truck. . Cerb if you can trump My offer GO for it..... LOL

 

[cerberusiam]

I give up... . Its getting to the point of removing My membership form the TDR... EVERY TIME SOME OTHER MEMBER POST THEIR INPUT ITS QUESTION BY YOU...

Just you Todd cuz YOU are my SPECIAL porject today.

I'm tired of the intellectual exorcises you put members through... "flow specs and circuits" Now I will put you through the intellect,What are the flow specs? what are the circuits? and how and the heck is the OP going to perform these on the truck. . Cerb if you can trump My offer GO for it..... LOL

Ok Mr Fluid Dynamincs Is Not Related to Fluid Mechanics, are ya ready??? Got a pencil handy????



CP-3 return flow spec <1000 ml\min. MOST pumps should fall into the 600-700 range give or take 50 ml\min.



How? Why the same way any enterprising person would do the injector return flow test, disconnect the CP-3 return flow line from the combing block in front of the filter housing and route it into a container. Do you really think the OP and the rest of us CANNOT do a simple thing like that? Do you really think YOU are the only qualified diesel mechanic around here? Oo.



Ok, how many circuits does the CP-3 have Todd? Can't tell by your posts becuase you post no useful information, only send it to ME ME ME, I am the ONLY ONLY ONLY person that knows how to fix it RIGHT RIGHT RIGHT!!



Diverging from your tendency to post NOTHING, I will put it out there for ALL to see. There are TWO return flow circuits and ONE bypass circuit on a CP-3. The COV controls how much flow is routed to all of them. At 40 psi or less case pressure a small orfice is uncovered for lube\cooling flow, above 40 psi the COV uncovers another port to route full lube flow thru the CP-3 and back to the tank. Once the case pressure hits 75 psi exces pressure is bled off and routed back to the tank to maintain case pressure at 75 psi. At 240 psi the COV routes pressure back to the INPUT side of the gear rotor pump to keep it from blowing itself up.



Now, when the COV fails from whatever the return flows CAN go high and rob fuel from the high pressure side thereby reducing rail pressure at cranking and\or cause rail pressure drops across the board. Is it common? No and I specifically siad that in my last post, BUT, it is something that can be checked. After all, you are the king of COV problems. Every problem anybody has YOU attribute it to one of 2 things, bad COV or too much pressure to the gear rotor pump. Forget all those posts you made, hmmm??



So, take a look back and TELL me who is posting what there buddy? I have yet to see you post ANYTHING that makes sense.



All you can do is tell everybody your cockamamy, yeah I said COCKAMAMY, theory that somehow magically 30 psi to the FRONT of a gear rotor pump that is pressuring the case to 75 psi is destroying the CP-3. Have you EVER posted ANY bit of proof that such a thing is possible? You RUN and HIDE ever single time I call you on it and ask for something other than opinions.



The last time I checked this is a TECHNICAL forum. WHERE is your contribution of ANYTHING remotely resembling something that makes SENSE??????



I point out specifically the post I question the ONE thing in there that was remotely realated and you go off on me. How about CAN the high pressure SALES pitch and save it for PM's, hmmm?



You wanna play, BRING IT ON!!!! Drop the *****y little sweater monkey attitude and throttle your ego. You AIN'T that good!!! #@$%!

 

[Prairie Dog]

Where's a smiley face eating popcorn when you need it?

 

[Prairie Dog]

#ad


Ok, I'm ready.

(Seriously, I'm learning stuff here so thanks to all involved)

 

[CPence]

I did not mean to sart a problem between two people, both are trying to help those of us with problems. I appreciate the input. My truck is starting great right now (temperature does not seem to make any difference). I will try and check return pressure, but will need to do some reading and try to figure out how to check it. Thanks again to everyone.

 

[CPence]

Is there a way to test the COV ??



Is there a anything to keep the fuel from draining out of the high pressure system after shutdown ??



I there any sort of a valve at the banjo fitting at the back of the rear head ??



Thanks Ches Pence

 

[cerberusiam]

Its tough to be exact testing the COV becuase of the multiple stages it has. Its all about spring pressure and the rate of the spring to hit the stages. About the best way to look for a problem is look at the CP-3 return flow to see if it is possibly stuck or intermittently jamming. Its like the FCA, you have to replace to see if cures a particular problem.



The injector return is orficed at tthe back of the head so it maintains something like 10-12 lbs of pressure IIRC. When the engine is shutoff the rail pressure is eventually going to bleed back to the tank. When you go to start the engine the ECU alternately fires injectors 1 and 6 to bleed any air out the rail till rail pressure hits a certain point then it kicks into its normally timing\duration algorithm.



On crank the system self bleeds until rail pressure gets a certain point then it needs to build a minimum of 3000 psi to fire correctly to start the engine. Normally thats a 2-3 count and it should fire. If it doesn't something is not allowing rail pressure to build or the ECU is not seeing parameters correctly.



The problem tracking WHERE the problem exists is the fact that rail pressure can go from 1500 psi to 3000+ psi in between the sampling times of the rail sensor. If it is a little bit slow or doesn't read pressure correctly you can get intermittent hard starts and slow starts.



Then there is the fact the FCA is a PWM electro-mechanical device that simply may not react correctly EVERY time, especially if its worn or dirty. Intermittent issues are just a pain to resolve. Thats why so many dealers just start replacing parts because the techs literally have no idea where to start and what they should be looking for when it could be slight nuances that cause the issues.



For 5 years my truck has fired warm or cold on a 2-3 count. Just lately I have noticed cold starts can go to 5 count and frequently won't stay running. SOMETHING has changed and it could be 10 things. Where to start is always the question.

 

[CPence]

Thank you for the response: Your information is what I needed. I now have something to work with if my truck acts up again (which I am sure it will). I will keep you information and use it for reference. I just can't see how all the injectors can go bad at the same time and I have several people that are all knowledgable that agree. I like your information. Thanks. Ches

 

[TCDiesel]

CPence don't approach CR with logic. . Knowledge of CR helps. . But its experience that will enable you to overcome all the short comings of CR. . Members or (most members) are helpful but being king of keystrokes has left many owners dumbfounded at the problem(s) they encounter with (CR). Most members own 1 truck... . they are sharing they experience of that 1 truck. or they are Kings of the kings of the keystroke. Their experience is helpful but limited. . I have a reputation to up hold along with 100s and in some cases 1000s of experiences with unlimited resources.

Now back to your question... . CR injectors have tolerances that are extremely close. . " so you hear the post I replaced 1-2 Injectors it solved my no start" Sure it will for a time,What you will never read about how the 1-2 failed on vacation and People like Myself have to deal with this... OK you replace 1-2 Now you want Me to Next air 4 more. . In some cases WHY would I want to get involved in this . . I cannot recount how many times I have shipped 4 just to find out the 2 replaced are the problem. . Now their are 2 types of injector with to types of versions. . What did the 1st seller push on the the owner. . I have a current owner with 2003 LB7 D-Max that form FLA and he was stopped by the State Patrol B/C he was spraying diesel fuel all over other cars. it was brought to Me over the weekend ,He just installed New Injectors, The seller Claimed they Were New... THEY WERE NOT GENUINE BOSCH,I am sure the engine is DONE it had a nasty knock when it left here, I replaced the 1 I pulled with a good used one, the tip was cracked on the one pulled. . This Owner is Now looking at $12k bill and miles form home. . :{

 

[CPence]

cerberusiam: Thank you for your help. I have a lot to do. cpence

 

[TCDiesel]

Yep, I only own 2 Cummins CR’s. But I did do a CR/drivetrain swap and slept at a Holiday Inn. I also have a friend who manages a big Cummins service center who has about 30 people working for him. I passed my CR symptoms to his CR mechanic who said run with it.



I guess I was lucky when I "logically" assumed that an faulty injector(s) was bleeding off rail pressure at crank. When one roughly understands how a CR works and sees 100 posts on the TDR about it, it was enough for me to buy a rail pressure gauge and confirm if by measuring rail pressure at crank versus idle. (I know enough from being technical developer that a digital gauge is going to sample). I bought a rail cap to cap off the injector at the rail, systematically removing an injector from the equation. it didn't take long - easy find, very repeatable diagnosis. Gave Cummins the engine ID and got the correct injector. Replacement was easy.



Now I could have replaced all 6, but the truck has been fine in the 3 years or so that has passed. The extra 2K was probably spent on my family at Yellowstone.



All that said I can certainly see why a shop would want to replace all six injectors, they don’t want the customer broken down or coming back with problems, which gives them problems. On the other hand if it’s your truck and you are accepting the responsibility (and injectors are $$$), you might not replace what might not be broken.

If the engine has less then 100k or 5 Years, I see no reason to replace Injector(s) unnecessarily in some cases. Yep I go to West Yellowstone 2 to 3 Times yearly, I spent Most of My Vacation time in the Rockies During the winter Months.

 

[CPence]

T&C Diesel: I appreciate your input, I am keeping it available. I just am not ready to spend that kind of money if it is not necessary. My truck runs so smooth with plenty of power after it starts I just can't believe it is injectors and you agreed with me (on the phone) that is is low mileage to lose all the injectors. I am still struggling to decide what to do. The truck is starting great and running good right now. I bought a can of starting fluid yesterday, so that I can use it (as you instructed) if the truck acts up again. Thanks again, I realy appreciate all the help and am sorry about creating the friction between people that are so helpfull.

 

[TCDiesel]

Just hang on to that either,,That way you will never be stranded.

 

[AStewart]

Did you find your problem?

 

[CPence]

I did find my problem. Number one and number three injectors were leaking into the return line and not allowing the common rail pressure to build up high enough to allow the engine to start. Two rebuilt injectors and injector tubes and almost $800. oo later and it is it's old self again.