Hello all- I've been a lurker for a while but this is first time needing to post. I recently was running very low on fuel and had to use some fuel from transfer tank (bad idea i know). After about 10 min. the truck had rough low idle as i'm sure i introduced some water and probably some contaminants from transfer tank. The next day would not start at all. From there I added 10 gallons fresh fuel and power service additive. Replaced the fuel filter twice. Cracked injectors to bleed. Truck sounded like it could fire at any time but never would. Took truck to a local diesel service outfit- have not heard good thinks about the dealership. The mechanic reports he changed the fuel filter again, low end pump checked out ok, 5000 psi at the rail when spinning, no engine or electrical codes. He says they do not work on Cummins very often- Mercedes, P Stoke, etc. He said he doesnt have the equipment for much more diagnostics. Any help or advise from similar problems would be much appreciated. I'm somewhat familiar with the common problems (VP etc..) but not much on specifics and I have read a lot of posts looking for ideas. Any recommendations to check next before taking dealership? Thanks for any help!

 

Welcome to the DTR. Sorry your first post a bad one!

First, Cracking a common rail's injectors lines and cranking is extremely dangerous, and serves no purpose. There can be pressures up to 27,000 PSI, and that can sever body parts.

Did you check for codes?
https://www.dieseltruckresource.com/...s-t224833.html

Your 06 does not have a VP, but a CP3.

 

You need to check rail pressure when cranking over. Sounds like excessive return flow from injector. You will need several miller tools to check limit valve and return flow.
INJECTOR RETURN FLOW TEST


1. ENGINE RUNS


--------------------------------------------------------------------------------


NOTE: Review Warranty bulletin D-05-24.

NOTE: Battery charger may need to be utilized if cranking speed is below 170 RPMs.


Does the engine run?

Yes

Go To 2

No

Go To 3



2. INJECTOR RETURN FLOW TEST @ 1200 RPM AND 1400 BAR RAIL PRESSURE


--------------------------------------------------------------------------------
1. Operate the engine until the coolant temperature is above 82.2°C (180° F).
2. Turn the engine off.
3. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
4. Install fuel system test fitting 9012 in place of the banjo connector.
5. Install a 5/16 diameter rubber fuel hose (Hose A) onto the test fitting and into a fuel container.


NOTE: This will be measuring the High Pressure Pump return flow for this procedure.
6. Remove the vehicle fuel return line (Quick connect) from the engine fuel drain tube.
7. Install a 5/16 diameter rubber fuel hose (Hose B) onto the engine fuel drain tube and into the fuel container.

NOTE: This will be measuring the Injector return flow for this procedure.
8. Start engine and allow to idle for 30 seconds. This step allows the flows to stabilize.
9. Using the scan tool, navigate to ECM view -> PCM Cummins -> More Options-> System Tests -> Fuel Pressure Override Test. Select Start, then press Next.

NOTE: While the test is running, record the FCA duty cycle % and actual rail pressure. Record the readings on the Cummins Diesel Diagnostic Worksheet located under e-files, service, Star center in Dealerconnect.
10. As you press the Run button to start the Fuel Pressure Override Test, move (Hose B) from the bucket and insert it into a graduated cylinder. The engine speed will elevate rapidly to 1200 RPM and the rail pressure will increase to 20000 psi (1400 bar). Collect the fuel until the Fuel Pressure Override Test times out (30 seconds).
11. Measure and record the amount of fuel collected in the graduated cylinder.

NOTE: Flow should be less than 160 ml for 30 seconds.
12. If the flow is less than 160 ml/30 seconds, the test has successfully passed. If the flow is greater than 160 ml/30 seconds, turn off the engine and remove all 6 high pressure fuel lines. Re-torque the high-pressure connector nut for each injector. Inspect for damage, repair/replace as necessary. Reinstall the high pressure fuel lines. Re-measure the injector return flow using steps 7 through 10 as a guide. Go To .
13. If the amount of fuel is still greater than 160 ml/30 seconds after re-torquing the high-pressure connector nuts, turn the engine off and remove the #1 high pressure fuel line. Cap the #1 fuel port using tool 9864 for the 6.7L engine on the fuel rail and re-measure the injector return flow using steps 7 through 10 as a guide. Go To .
14. If the amount collected is less than 160 ml/30 seconds, remove and replace the #1 Fuel Injector and #1 High pressure connector. If the amount of fuel is still greater than 160 ml/30 seconds, repeat step 12 for injectors 2-6.


SPECIFICATION: Less than 160 ml total fuel return flow for 30 seconds.

Repair

Test Complete.



3. INJECTOR RETURN FLOW TEST DURING ENGINE CRANKING @200 RPM WHEN THE VEHICLE WILL NOT START


--------------------------------------------------------------------------------
1. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
2. Install fuel system test fitting 9012 in place of the banjo connector.
3. Install a 5/16 diameter rubber fuel hose (Hose A) onto the test fitting and into a fuel container.


NOTE: This will be measuring the High Pressure Pump return flow for this procedure.
4. Remove the vehicle fuel return line (Quick connect) from the engine fuel drain tube.
5. Install a 5/16 diameter rubber fuel hose (Hose B) onto the engine fuel drain tube and into the fuel container. Make sure test lines are straight and slope downward their entire length. This is to avoid trapping air/fuel in the lines while testing.

NOTE: This will be measuring the Injector return flow for this procedure.
6. Unplug the injector harnesses at the valve cover, unplug the harness connector to the FCA.
7. Crank the engine for least 10 seconds until fuel starts to flow out of the pump and injector return hoses. Turn Key off when finished.
8. Let all the fuel drain out of each line before continuing.
9. Place (Hose B) into a graduated cylinder.
10. Crank the engine for 10 seconds (Go from Key off to Crank back to Key off). Do not leave the ignition on between tests.
11. Let all of the fuel drain out of the injector hose.
12. Record the amount of injector return flow for a 10 second crank.

NOTE: Flow should be less than 40 ml for 10 seconds of cranking.
13. If the flow is less than 40 ml, the test has successfully passed. If the flow is greater than 40 ml, remove all 6 high pressure fuel lines and re-torque the high-pressure connector nut for each injector. Inspect for damage, repair/replace as necessary. Reinstall the high pressure fuel lines. Re-measure the injector return flow using steps 7 through 12 as a guide. Go To .
14. If the amount collected is still greater than 40 ml, remove the #1 high pressure fuel line. Cap the #1 fuel port using tool 9864 for the 6.7L engine on the fuel rail and re-measure the injector return flow using steps 7 through 12 as a guide. Go To .
15. If the amount collected is less than 40 ml for 10 seconds after capping the #1 fuel port, remove and replace the #1 Fuel Injector and #1 High pressure connector. If the amount of fuel collected is still greater than 40 ml after capping the #1 fuel port, repeat step 14 for injectors 2-6.


SPECIFICATION: Less than 40 ml total fuel return flow for 10 seconds.

Repair

Note: DTCs will be set by this process. Remember to go in and clear all DTCs from all modules. Test complete.
PRESSURE LIMITING VALVE TEST

Possible Causes
PRESSURE LIMITING VALVE DIAGNOSTICS

PRESSURE LIMITING VALVE
--------------------------------------------------------------------------------
1. Using the scan tool, measure the rail pressure and determine if the rail pressure is excessive (above 185,000 kpa/26,831 psi), if it is, troubleshoot for excessive rail pressure first.
2. Remove the banjo bolt from the pressure-limiting valve on the fuel rail.
3. Install fuel system test fitting (9013) into the pressure-limiting valve.
4. Attach one end of a fuel hose to the fuel fitting and put the other end of the fuel hose into a container.
5. Perform the tests listed below to determine if the pressure-limiting valve is leaking.
6. a. Operate the engine at idle and watch for fuel flow into the fuel container.
7. b. Operate the engine at idle and actuate the high pressure safety valve test with the scan tool. Watch for fuel flow into the fuel container.
8. If fuel flows into the fuel container, replace the pressure-limiting valve. If fuel does not leak from the pressure-limiting valve, the test is complete.
9. NOTE: do not drive the vehicle with any portion of this test kit installed.

 

thanks for the info guys. will keep trying to collect similar info to figure this thing out. anyone else have any thoughts?

 

well from what i se from workin on them if. u don't have alot of tools. u can pulls filter out and turn key on it will fill the filter bas up. while engine is cranking the lift pump should be anywhere from 5 to 11 psi. you can check.

then if u do the test for the fuel pump and it fills the cup up. the ur pump is good.

u can by the cap for the fuel rail and you can block off each port on ur rail to if ur truck starts then that inj is the one bypassin in the head. but i have also seen where the check valve in the back of the head has bypassed.

sounds like you either got a injector bypassin or the return check valve isn't holding.

 

also first is first. check for fuel leaks. check to see if you have engine speed from ur sensors. cause all of those things can make it not or hard to start.