the caps are alot cheaper that a new relief valve

 

alot cheaper at that!. how much does it cost to have a rail pressure test done at a dealership? rough estimate?

 

It a long drawn out process. Thinks it 3.5hrs, tech will measure return flow to tank, then cap each line 1 @ a time, since #2 is behind intake manifold, it comes off, back on, then down the line, checking return flow. If its an injector, the fuel return goes up. Stuff that can cause hard starting, CP3, leak in the hi pressure circuit, injectors, or the rail cap. Cheapest place to start is with capping the rail cap. Pull out the banjo bolt, tapped it, put in a pipe plug, or trade out with a known good one from a buddy. Its not a really easy system to check out @ home. Also think the tech raises the cps output pressure while checking the fuel return of the injectors, need dodge scan tool. Dodge made sure that you cant take your truck to a Cummins dealer. 03 & newer, Cummins cant talk to truck/motor, that info came from Western Canada Cummins trainer & local cummins dealer as I tried with mine. We sell the 6.7l in small freightliners, same fuel system as the 5.9 in the dodge.

 

Han salo- thanks great info. Should i take it to the dealer then? or should i buy a rail pressure guage and monitor it once im up to temp and have issues? i highly doubt its an injector but im not against the idea as its common on the 03'. Jordan

 

Do you have a friend to swap parts with?Could be an fca or the RP sensor.You are correct on the problems with the injectors in the 03's.it can get expensive throwing money at it blindly but it can also get equally expensive letting the dealer diagnose it.Gauges would help and are a good investment if you plan on running the downloader.

 

i do have one friend i could swap with. but i think ill buy a guage first so i can compare more once we swap parts. if i can convince him to lol. but thanks for everything.jordan

 

A rail pressure gauge is going to be less than the test at a dealer. A cap on the RP valve is even cheaper. All you have to do is thread the inside of the banjo bolt for a 1/8 pipe plug and reinstall. That will tell you if its the relief valve causing issues.

If its an injector you may or may not see it on the RP gauge unless its a massive leak. You will need to do an injector flow test to validate one or more is bypassing too much fuel.

 

if i have a leak somewhere passing by alot of fuel would i still have s smooth idle and no loss of power?

 

Yep, the CP-3 can eaily supply enough to overcome an injector leaking by when the engine is running. However, an injector leaking will cause issues for the CP-3 to build enough pressure with the just the starter motor and 200 rpm's.

The CP-3 needs to build 3-5k pressure to get things to start correctly and even then if there is enough leak by they will exhibit a hard start condition.

 

no 6 oh no- thanks for the good insight. i was wondering what the best way to check things like cam sensors and other sensors would be? obd reader? or what. i had been reading a few other hard start threads and read about it somewhere. just a thought.

 

I have heard of a few that had a flash to fix the long crank problem and it worked. Others it didn't work for.

There is just an issue in some trucks that the sensors don't synch right away and the default to start is relatively long. Juat another idiosynchrast of the manuals.

 

yeah a guy i talked to said that when his truck was hot his cam sensor would take awhile to make sure the position was correct before fireing. if that makes sense. should i take it to the dealer to get it flashed if my cp3 checks out once i get a guage?

 

I did fuel checks on a ISC today, which is big brother to the ISB. Its a common rail, different pump. 1st test is return flow of all 6 injectors, if in spec, if not, cap 1 fuel line @ a time, repeat test to find the leaking transfer tube/injector. Maybe loose nut that holds the tube against injector. If not replace tube/injector. But you have to have a Cummins program to up the fuel pressure to 20,000psi+ or whatever dodge has. 2nd test is return flow from injection pump, with higher pressure again. 3rd is check fuel return of the pressure relief valve, again with up pressure. All test done @ idle. These is for the hi pressure side of the system, there is also the supply side or low pressure, then the return circuit. It not to bad to check out, but need the tools. I know the computer @ work wont work on my truck, also asked our local cummins dealer, said nope too. Last year of truck they can talk to is 02. Local dodge dealer wanted 3.5hrs to check out the hi pressure side. If anybody has more or better info than me, please post, very willing to learn more.

 

han solo- thanks for everything. your info has been great and i understand most of it haha. suprisingly. imreally thinking about taking it to a dealer but i dont want them to think im full of sh*t when i tell them everything that i have checked, and what i know and dont know. should i tell them to just check certain things or just check the whole fuel system and re flash it? TIA, Jordan.
ps- i probably dont have the money to fix it but i wanna get it back on the road or atleast figure out whats wrong. Im praying its not an injector

 

Im not sure how dodge dealers check out the fuel system. From what I have read on here, must do cylinder cut out test, then something with the solenoid. To me, those test are to find a dead/weak cylinder. Not a hard starting issue as you say that you have. You said that you have a fuel leak @ the CP3, I would look @ that closer. Fuel leaks are bad thing in a common rail system. They have kinda taken the home mech out from working on these things, needing the special testing tools. Which sucks, even for me. Thinks somebody already posted this, if you have a torque wrench, can make sure the transfer tube nuts are tight. Have to remove fuel lines, for safety, have glasses on, release any pressure if there is any, or let it sit for awhile. Then tighten the nuts. Its about all you can do, good luck.