If you are pretty sur it's not the LP,then I suggest pulling the return line from the rail,& start the engine.There should be no fuel at idle comeing from the rail return.The return line itself will pump fuel from the rest of the system.If there is fuel leaking from the rail return. Put it back together,& run the engine to governed speed. This will command the pressure relief valve to reseat itself.,& check it again.If it's still leaking,the rail pressure relief valve needs to be replaced.If there is no fuel leaking from the rail,it's something else.Given that it won't start when cold,I'd have some starting fluid ready,& do it first thing.It may seal up again once it's warmed up a bit.If that's not it.Let me know,& I'll run you through the procedure to test the injecter return flow.

 

Big wheels How do you disconnect the return line. I see a line on the top of the rail and one on the bottom. If you remove either bango bolt and pressurize the system i think there would be a mess real quick unless im wrong. What line is return side. I went to change lift pump how do you get the fuel line off i do not see a clip . Do i have to cut the line and replace?

 

Longbed.The return line you want to disconect is the banjo fitting on top of the barrel looking thing right next to the rail pressure sensor.The barrel thing is the pressure relief valve.It will be hard to do this without makeing a mess,without the adapter/testing tools.The CP-3 return is also plumbed into the same steel line @ the filter.This will need to be removed,& the fuel captured,& be able to look for fuel leaking from the relief valve all at the same time,but with some inginuity,I'm sure it can be done.At idle speed,there should be No fuel leaking from the relief valve.
As for the fuel pump.What year is your truck,as the years after 05 moved the pump into the tank.
Fill out your sig,so I can see what your truck is.

 

Bigwheels, I did check the press relieve valve on the rail like you said ,there was no fuel coming out at idling,there was from the banjo ,but thats normal like you said.

So the next thing to do is check the fuel return from each injector ?

Can you give me a few directions how to do it the best way ?

thanks Sterling

 

You cannot check the return flow on each injector while the injectors are in the truck, only the total return flow for all of them. The only way to check them for certain is pull them and do a bench test.

The truck should start with the FCA disconnected and will rattle like crazy but it will tell you if the IP is generating enough pressure and eliminate the FCA as being the culprit.

Plugging off the return line will tell you if there is too much fuel bypassing and indicate a bad injector. You will then have to dig a little farther.

Good luck.

 

Is it not possible to disconnect every return line on all 6 injectors and replace them temporarily for 6 hoses and run them separatly into 6 containers ?
that way you can find out which ones are leaking ,or am I wrong ?

So I can uplug the connector from the fca on the cp3 pump ,and start the truck ? if the injectors are good I should see more railpress at starting ?

The only thing thats left is injectors,(if fca is good )

I think I need a set flux 1,5 s

Thanks for help guys ,I feel I come closer to my problem.

 

Uhhh...NO please don't do that. I don't think it is even possible with the routing of the return lines, plus, it is just a bit dangerous. If you haven't done so retorquing the crossover tubes at the injector might help also.

If you have a slow/no start condition it can help eliminate the FCA as a problem. Unplugged the FCA should go to full pressure (as much as the CP3 can generate at starter speed). If low rail pressure is caused by an injector passing fuel this will help to point the way.

Slow starts are a pain to track down as there are so many things it could be, electrical, meachnical, pressure, etc. Good luck.

 

The correct way to check return flow from the injecters is to remove the return line from the back of the head,& measure the amount of fuel that goes into the beaker in 1 minute @ idle with a graduated beaker.(2-stroke mixing gug with all the Ml.lines on it).You buy the rail caps from bosch,or cummins,& plug off the rail,& the injector 1 at a time,& perform the test again.This is best done by a profesional.There are specs for the flow with only 5 of the 6 injectors working.When you get to the one that is leaking,it will obvously put more fuel into the beaker in 1 minute.
Re-torquing the transfer tubes in the head may be a good place to go too.Just in case that's it.It's easy to do.
Unppluging the FCA at start up won't nessisarily tell you anything,as the FCA is allready @ full flow during cranking.It decreases the pressure as it builds after starting to the level it wants to see.
As long as the pressure relief valve wasn't leaking any fuel during the test you allreay did.I would now have to suspect the injectors are the culprit.Realisticly,unless the FCA is sticking,that is the only possibility left. Unpluging the FCA,& hearing the truck rattle should tell you that the CP-3 is working.(Just make sure the return line from the rail is conected,or something WILL blow up.!!)The only other way to do it is to have the diagnostic software to read what's going on in the computer while it's starting,& running.If you can take it to the truck dealer you were talking about,they should be able to do all this for you the right way,& with the right tools.Good Luck.

 

Hey Guys

I think we have find the problem,by retorqing the transfer tubes to 3,5 kg/m the truck started fine ,even when cold this morning +- 25-28 F it started in 2-3 revolutions.
Also we installed the walbro kit.
The next few days I will hope that all the starts will be ok.


Thanks for help

sterling

 

Tranfer tubes ? The tubes from the common rail to the injector tubes? And you changed the lift pump. Did you do in any order or did both at the same time?

 

We changed all in one time ,i know its stupid as you never know the real problem .
but I,m glad its starting now.
We could turn them some to reach the 3.5 kg/m torque.
I would say try it ,its easy and cost nothing,only thing ,the nut that pushes the steel tubing onto the transfer tubes was somewhat seized to the steel lines ,so if you try to take them off you will see it looks like the steel tubing is turning too,and then sudden it breaks loose.

I have more railpress now during starting ,i see about 1600-1800 psi now.
that was 1000-1200 and didn,t fire with that pressure.

sterling

 

Glad to hear it.

 

Update: Changed the stock lift pump. It started for the next 2 days without being plugged in. Third day no start just the same as before. PLug it in and it starts. Is this because the relief valve got reset when i drained the system?

 

If you're talking about the rail pressure relief valve.It only resets when the ECM tells it to.Usually when at full throttle.You can make it reset itself by running the engine to full throttle in neutral for a moment.(20-30 seconds).This usually commands it to reset.But if changing the stock lift pump fixed it for a few days,& now it won't start again,I'd say you may have something plugged up.Filter? Kinked line,or something like that.Try bypassing the trucks fuel tank,& see if that does it.If nothing else,it will tell you what it's NOT.
I don't remember if we went over this allready,but is there any smoke when it's cranking? White,black,clean air? Any codes?

 

Thats a problem some have, if the bolts on the connector tubes arent tight enough it will not start. After doing my injectors and installing everytihng my truck wouldnt start at all. went back and tightened the tubes some more and it fired up. I believe its some sort of a safety feature in case you do have a high pressure fuel leak so you dont kill yourself.