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2004 dodge cummins, engine surges at 2500 rpm and up. if you hold the throttle the egine will go to high idle,stay there for 3to4 sec then return to a rough idle. some black smoke while surging and at the high idle. already replaced the throttle sensor it had a code for that. no change..checked fuel supply to com. rail pump, good psi and no air in a clear line.rail psi steady at 2500 when engine is surging.also checked resistance in all 6 wires for throttle petal and idle val switches..39437.4359673264
HiCustomer
Thanks for the question. The problem you are having looks like a fuel transfer pump problem. The fuel transfer pump can have the correct pressure but have low fuel flow. You need to measure the amount of flow from the fuel transfer pump. The spec. are : More than 450ml of fuel in 10 sec. Most of the time if you have black smoke it is because of a low fuel supply problem but when you state that the idle stays up high when you let off the throttle that sounds like a fuel injector hanging or stuck open. Do you have any trouble getting it to start?
Mike
450 ml is the spec for the 99 to 2003 pre comman rail.the preasure doen't drop and no air in system we have a clear line in it.the mis-fire will start at 2500 and then if you keep the rpms at 2500 to 2700 it will go up tp a high idle by its self,stay there for about 3 to 50sec. then return to idle.
Thanks for the reply, Here is the test proceedures for the fuel transfer pump:
IN-TANK FUEL LIFT PUMP FLOW/DIAGNOSTIC TEST PROCEDURE
For a complete wiring diagram Refer to Section 8W.
1. *IN-TANK FUEL LIFT PUMP FLOW/DIAGNOSTIC TEST PROCEDURE
1. Using the Scan tool, check for DTCs. Troubleshoot any active DTCs before performing this test.2. Disconnect the wiring harness from the lift pump at the fuel tank module connector and inspect the pins for damage. Fix or replace any damaged component.3. Connect a voltmeter between the fuel lift pump supply and return pins at the fuel tank module connector. 4. Turn the ignition to the on position. Use the Scan tool to actuate the fuel lift pump, record the voltage on the voltmeter.5. If the voltage is greater than 11.5 volts, go to step 14. If the voltage is less than 11.5 volts, go to step 66. Using a voltmeter, measure the battery voltage to determine that the voltage is greater than 11.5 volts. If the voltage is greater than 11.5 volts, go to step 7. If the voltage is not greater than 11.5 volts, troubleshoot for low battery voltage.7. Remove the fuel lift pump relay from the PDC. Use a voltmeter to measure the voltage at the fuel lift pump relay voltage supply pin in the PDC. If the voltage is greater than 11.5 volts, go to step 8. If the voltage is not greater than 11.5 volts, fix or replace the harness.8. Remove the fuel lift pump relay from the PDC. Install a spare relay in place of the fuel lift pump relay. Using the Scan tool, actuate the fuel lift pump. Use a voltmeter to measure the voltage between the fuel lift pump supply and return pins at the fuel tank module connector while the fuel lift pump is actuated. If the voltage is greater than 11.5 volts, replace the fuel lift pump relay. If the voltage is not greater than 11.5 volts, go to step 9. 9. Disconnect the wiring harness from the fuel tank module. Remove the lift pump relay from the PDC. Using an Ohmmeter, measure the resistance of the fuel lift pump power supply wire between the PDC relay output pin and the fuel tank module connector. If the resistance is less than 10 ohms, go to step 10. If it is greater than 10 ohms, fix or replace the harness. 10. Disconnect the wiring harness from the fuel tank module. Remove the fuel lift pump relay from the PDC. Using a voltmeter, measure the voltage between battery negative and the fuel lift pump power supply wire at the fuel module connector. If the voltage is less than 1 volt, go to step 11. If the voltage is greater than 1 volt, fix or replace the harness. 11. Disconnect the wiring harness from the fuel tank module. Remove the fuel lift pump relay from the PDC. Using an ohmmeter, measure the resistance between battery negative and the fuel lift pump power supply wire at the fuel module connector. If the resistance is less than 10 ohms, fix or replace the harness. If the resistance is greater than 10 ohms, go to step 12. 12. Disconnect the wiring harness from the fuel tank module. Using an Ohmmeter, measure the resistance of the fuel lift pump ground wire between the fuel tank module connector and battery negative. If the resistance is less than 10 ohms, go to step 13. If the resistance is greater than 10 ohms, fix or replace the harness. 13. Disconnect the wiring harness from the fuel tank module. Using a voltmeter, measure the voltage between the fuel lift pump ground wire and battery negative. If the voltage is less than 1 volt, go to step 14. If the voltage is greater than 1 volt, fix or replace the harness. 14. Reconnect the lift pump connector. 15. Remove the fuel pump supply banjo fitting from the fuel injection pump. 16. Install fuel system test fitting 9014 into the fuel injection pump. 17. Connect one end of a section of fuel hose to the test fitting. 18. Put the other end of the fuel hose into an empty fuel container. 19. Use the scan tool to actuate the fuel lift pump. 20. While the lift pump is running, move the fuel hose from the fuel canister into a 1000ml graduated cylinder for 10 seconds. 21. Read and record the amount of fuel in the graduated cylinder after 10 seconds. 22. If you have more than 430ml in the graduated cylinder after 10 seconds, the test has successfully passed. 23. If you have less than 430ml of fuel in the graduated cylinder, inspect the fuel supply line from the fuel tank to the fuel filter housing and the fuel supply line between the fuel filter housing and the high pressure fuel pump for signs of damage, replace as necessary. 24. If no damage is found, replace the fuel filter and retest. 25. If reading is still less than 430ml in 10 seconds, remove the fuel tank and fuel tank module. Inspect for damage and/or debris in and around the fuel tank module. If module is damaged, replace and retest. 26. If the module is not damaged, replace the fuel lift pump and retest to confirm fix.
Test complete
Repair
This is the test for the pump if you have had it updated to th fuel transfer pump in the tank. If the fuel transfer pump is still mounted on the back of the fuel filter housing the specs on it are : 450ml in 10 sec of running.
Have you run a fuel injector return flow test ? I still feel the You could have two problems. I feel the surging and miss-fire is caused by low flow from the transfer pump and the high idle is a result of a leaking fuel injector(s). Did you run a fuel transfer pump flow test? if so what were your results?
Thanks , Mike
we fig the problem out it was the injectors..but we tryed to find the one or two that were causing the problem because normaly all 6 don't go back at once..but in stress condition as these were we took 6 off the self to see if we could make the problem go away it did . so then we tryed to find the 1 or 2 that would cause the prob.it seemed like the whole set was bad. maybe the truck had gas ran through it..it seemed like no matter which 1 or 2 we tryed the prob came back..any further thoughts on this..