I will start off by saying i'm not sure where to post this so I will pick here.
My 03 cummins has been slowly getting worse on the starting. It started off taking 15 seconds to start. Then 30, then a minute, now I have to use Either. I decided to try and fix it, so I realized I have no diesel testing tools. I pay a local shop to run a scan and check pressures. I have 3-5 psi during cranking from the lift pump then up to5-7 psi when running. 3000psi CR pressure at cranking. (this was a few weeks ago when i didn't need either) 1900psi CR pressure to 2200psi during test drive.
So the shop wants to take the truck apart and send out the injectors and injection pump for testing. I gotta get to work, so I decide to fix it myself. For all of you rolling your eyes, I am an aircraft mechanic by trade. I work on jet engines. So how diferent can it be? Let me tell you, a lot.
So I decide the lift pump needs R&Rd. so I install a FASS Titanium 95 GPH lift pump with fuel heater. This fixed it for 3 days. back to needing either sometimes and sometimes not. I decide then to replace the check valve in the back of the head for the return line. And to pull and inspect the COV cascade overflow valve. I will replace it if I find any issues. this work to be done this weekend 1-25-14. My question is what else could cause the hard starting issue I'm having? Any advice would be appreciate.

 

The 5.9 doesn't use glow plugs, it has some other strange apparatus for cold starts.... Are you just having issues with cold starts? Or, every time? Post up in the Diesel (Cummins) section, folks there can help ya out.

Welcome to DF.

I'll move this one there for ya.

 

so you removed your grid heater, replaced the lift pump because I agree 3-5psi is not enough....

should be at least 12-20psi

enough with the ether! just going to cause yourself problems using that stuff.. get the injectors inspected and tested. may be time to get them rebuilt or replaced.

common rails are notorious for injector failure. particularly with cracking the tips.

As for how hard a diesel is to work on? they are simple motors... less complex then gasoline.

it is a 4-stroke motor, but only air goes through the valves. fuel is injected at the end of the compression stroke to cause instant detonation, (diesel fuel is combustible and explodes when compressed) then the exhaust stroke happens which forces the hot exhaust out through the turbine of the turbo which drives the turbine of the turbo. the harder the turbine is driven, the harder the compressor side of the turbo is driven which is force feeding air into the intake of the diesel.

there is no air butterfly in the intake of a diesel.. they are wide open intakes and throttle is 100% controlled by how much fuel is injected.



simple engines.



electronics can be a bit more complex, but not too much more..

check the injectors, and also check the IAT sensor and make sure it is reading correctly. IAT sensor reading will determine the injection timing. timing retards when the temp is cold, and advances when it is warm.

I rarely use my grid heater, but I have had to use it before when it was a brisk 6* outside. truck didn't want to fire up till I let that heater cycle once then it fired right up...

they are on there for a reason. diesel fuel burns better in a warm/hot environment.

 

Thanks for the Info Jigbop.
I was kinda joking about the dificulty of a diesel engine. I am an Aircraft Mechanic and work on Jet engines. They are basicly the a diesel engine. Just no injector timming. Once the Nozzles (injectors) start to spray they stay on. you adjust power by adding more or less fuel from the fuel control (injection pump). So basically the same in principle. And as far as the turdo, well it is basically a single stage jet minus the burner section but enough about that.

What and where is the IAT sensor?
Is it possible to check the rail pressure with a mechanical gauge? I brought home a 35000 psi gauge hopping to figure out a way to chek rail pressure at start up. Any info on that would be great. I know that the CR usses a pressure sensor to tell the ECM the rail pressure, and that a scanner or some programmers can use the same signal but I dont have one and am trying to figure out another way.
Thanks,

 

It should be possible. Though I am not a common rail guy, so my experience with them is limited.

I own a 2nd gen 24v, so my experience and knowledge is mostly with the VP44 injected 24v.

I would think that there would be a test port on the fuel rail itself that runs along side the head on the drivers side, but it's been too long since I have been under the hood of one.

If not there, I would think that an aftermarket company makes an adapter to hook a gauge in between the fuel rail and the CP3 pump(s).

 

just wandering did you ever find out the solution to your problem? i have the same problem. have had the batteries and fuel pump replaced. fuel heaters checked and have no ideal what is wrong. i don't want to replace the entire engine piece meal any help would be helpful

 

Up date:
I was able to check rail pressure, not easily done. I have 3000psi at crank this is not enough for starting. Once it starts psi jumps to around 12000. So I'm convinced its the injectors. Now the question I have is can you replace the nozzle and fix the problem or do I need to R&R the whole injector? My thinking is the electronic portion of the injector is working its the nozzle end were the "sealing" takes place that is bad. I will admit I could be wrong as I have never had one of these injectors apart. Any suggestions or advice? Thanks

 

UPDATE:
Ordered new yes brand new injectors yesterday with a 50HP hone job. Finally decided to bite the bullet and go with new instead of reman. I wish I could say the price was decent but compared to Gen 1 and 2 well you get it.
All in all I am happy with the price considering $2750 with shipping and new connector tubes:-)
So I will be busy this weekend. I will let you know if this actually works or if I still need an injection pump also.

 

And the 6.7's are more expensive... In 2010 I was reading about people spending $9000 for a set of 6.7 injectors (installed).

Whereas I got a set of injectors for my 12 valve for under $700.

 

$700 would be nice. I think I did ok on price for new Bosch injectors. I had a local shop quote me $5000 to install reman injectors. It would've been done sooner but I think I will have a better system doing it this way. Plus I get to learn all about my fuel system the hard way so I wont forget it easily:-)
I took everything apart last night all that is left to do is actually pop out the old injectors. Just waiting to get the new ones!