Can any of you guys tell what railpressure you have during cranking ?
Mine is very hard to start ,I have to crank for 8 - 10 seconds ,with a warmed up engine ,and see between 1000 and 1200 psi (on the tst with r49),should this ok ?
I thougt it has to be higher ,like 2500 psi during starting,or am I wrong?
When the engine is cold ,I have to crank forever ,so I use a little ether ,because it will not fire up without.
I,m trying to locate the problem,during driving I have 5000 at idle ,and around 22000 psi at 3000+ rpm,this sound good to me ?

what if 1 or more injectors are leaking?and therefore the railpress is not enough to fire her up ?

Or could it be a valve in the rail that is leaking ?


Every suggestion is welcome ,as it is my daily driver and can not miss the truck.

thanks Sterling

 

It could be either. A seized injecter&/or a leaking pressure relief valve may be the problem.I'll have to check this in my manual to be sure,but the rail pressure @ cranking speed should be about 5000#+/-. My book is at work,so I can't check now.Either way,even in the old mechanical systems injecter opening pressure is about 3500#. 1500# won't fire it.

 

Sterling have you checked your grid heaters to see if they are working??

Kevin

 

Yeah I checked what I could ,grid heaters are fine .
It started in the winter when temps drops below40 degrees it just would not fire up.
So I keep plugged it in,and it start up no problem.
I new its going to be repaired sometime ,but the summer is coming here ,so I expected no problems,and time enough to find the problem.
Now it even would not fire up when its warm ,even when the engine is warm ,and I start it after 1 hour it will not fire up,i have to use a little ether to fire it up.
Running is fine ,good power ,no strange sounds,good mileage,good idling.
I tried everything ,take the predator off,back to stock,tst r 49 off,on, tried higher rail press,nothing would help.

My guess was I,m having not enough rail press during starting,(1000-1200 psi)
battery,s are good,starting speed is normal.

I did a search and could not find a leaking rail press relief valve ,so I was thinking could this be 1 or more injectors that leaking fuel?
And that the fuel return is to much ,so it won,t build enough rail press ?

thanks for input

sterling

 

I have been having the same problems as you. Read in the help section NO START 20 f. Carp got his truck to run after 6 injectors were changed. How many miles on your truck sterling?

 

My truck has 53K now ,and I,m having this problem for months now ,I really like to know from a ctd owner with a rail press gauge what pressure he sees at starting ,just before the engine fires.
I have no problem with buying 6 injectors ,as long as that would be the problem.
And not ended up with a lazy cp3 pump that have to be replaced too

thanks Sterling

 

Sterling, my truck has a similar problem. Was told by Dodge that a supply line is etched and leaking fuel back into the rail causing excessive rail pressure and not letting engine start. Should have a code for excessive rail pressure - not sure what the number is. Problem started with progressively longer cranking to start. Now, a little shot of ether and it fires right up. Dodge wants to replace all 6 injectors @ $450. each + labor. But get this, you have to also buy the supply tube kit too.
I'm thinking that there is nothing wrong with my injectors, engine runs great, no loss of power or fuel mileage, no missing, no leaking back into crankcase. So, if it's the supply tube, sold separately, why can't we just change out the tubes?? Dodge won't agree.

 

I don,t think I have a higher rail press,I think I ve got too low railpress at starting.
I,ve been told by a diesel engineer that it needs at least 4000 psi to fire the engine( I,ve got 1000-1200)
But I need to be sure ,I hope there will be someone overhere that can tell what railpress is correct at starting?

thanks Sterling

 

As I said before. The opening pressure is about 3500-4000 psi.Any pressure lower than that won't lift the needle off it's seat in the nozzle.If you have a gauge,& it only reads 1500 psi. Your engine won't start.Ether just gets it spinning fast enough to overcome the leakdown,& presto,the pressure will then fire the injecters.Why you're not building enough pressure is the question then.

 

The 3rd gen injectors are electrically fired. There is no pop pressure to work with. You can't spin these engines fast enough to create that kind of pressure with the starter


IIRC, the start pressure was supposed to be around 1700 psi for a CR. I can't remember the source but remember thinking it was about half of idle to start. If your chasing a hard start condition have you had the return flow on the injectors checked? FCA checked? Good luck.

 

Where can I check the return flow from the injectors?
And how much have to flow return max ?

thanks sterling

 

Why not just go back to the dealer and let them fix it you only have 57 k on a 100 k warranty. Just remove the extras. Does dodge dealer have a way to test each injector seperatly to find the ones that leak down. I went to a diesel injector shop today and asked if they could test mine if i took them out. They said they could only exchange them. I guess that was a no and want to sell injectors. There has to be a way to test them?

 

The injecters are electronicly fired.However they still have a standard nozzle in the bottom that has a spring that has to be overcome to fire it.So there is still opening pressure just like the old ones.It just can't be tested the same way.I'll check my manual when I get back to work tomorow,& get a spec for you,if I remember to do it. You can't test the return leakage yourself unless you have the spec's,& know what you're doing.I'd take it to a Cummins shop,& have them check it out if your dealer can't figure it out.If your in NW Washington,PM me.I'll take a look at it for you if need be.

 

You have to have some special tools and the specs to do it correctly. Any competent tech should be able to get the specs and run the test along with some others that might help pin point the problem. You really need to find a good diesel shop that knows what they are doing. Good luck.

 

No, pop pressures are a jerk pump design not CR. The way it was explained to me is the springs are for positive seating of the needle. The injector has nothing to do with any opening pressures. They only react to open and close commands via electrical current. Pressure is controlled by the FCA and can be high or low depending on demand. The injectors fire for a certain duration based on demand and that is all calculated by the ECU. With the pressures you are talking about the truck would never start.