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Dodge Ram Cummins Diesel Questions



  • Think i finally figured out my problem with truck lagging, its my lift pump and injector pump acting up, my buddy told me to put a airdog system on it,,, looked into them and they seemed like more work than i have time and money!!! Anyone recommend something that would be a little easier and fix this issue? i want this problem fix the right way though because i heard that its common problem with the 24 valves and airdog prevents this??
  • dasboot72dasboot72 Posts: 115
    Why do you suspect both the lift pump and the injection pump? The lift pump is the common failure. If you aren't getting fuel to your injection pump via the lift pump, things are not going to work correctly.
  • Thats how i felt my buddy who has had this happen though told me it could be both that my lift pump went bad making my injector pump work harder making it go but i think im going to just try the lift pump for now, whats ur opinion on airdog pumps he put one on his truck and said it was the best choice?? i know u had said dodge does something similar putting fuel pump in tank.
  • dasboot72dasboot72 Posts: 115
    I don't know anything about irdog pumps but I do know the redesigned pump from Cummins comes in a kit that replaces the original pump with a pass through, and puts the pump into the fuel tank as a fuel tank module replacement. There is also a simple wiring harness to install to send power to the now tank mounted pump. I have probabally installed 50+ of these kits and have never seen one fail. Also keep in mind that Injector pump DTC's may set due to lack of fuel to the injection pump rather than an actually faulty injection pump, which by the way is VERY EXPENSIVE. Fix your lift pump and get on with life!
  • (the two problems did NOT occur at the same time) I have two issue I would like some guidance on. (1) When I am driving normal and the transmission attempts to shift into lock up at about 41mph it seems to hunt in and out of lock up. If I accelerate above 45 it will go into lock up with no problem.. I have bee told that it could be the TPS and I have checked the voltage at the TPS.. At idle it is .49 volts and at full throttle it is 3.45volts. Any ideas?
    (2) Just recently while travelling down the interstate at about 60mps the truck lost pulling power as if the fuel was just shut of momentairly then returned to normal.. I have replaced the fuel filter and also added water rerover in the tank with no difference..I can accelerate fairly agressively when it is in the lost power and it makes no difference until it recovers... Any suggestions..
  • dasboot72dasboot72 Posts: 115
    Although you may have 2 seperate issues they may be only one issue. First off if you have the original block mounted lift or transfer pump it has most certainly failed. The new design relocates the pump into the fuel tank. The second issue could be a TPS with a glitch around lockup but RFI will cause the TCC to perform erratically. The most common source of RFI is from a faulty fuel transfer pump. You need to get that issue taken care of adn then see how your lockup is working. Any further questions?
  • Thanks DASBOOT.. Do you know where I can get one other than the dealer?? Prices I am getting there is aroud $600.00 with conversion kit.
  • dasboot72dasboot72 Posts: 115
    I do not know where else you can get one. I am a Dodge dealer mechanic and I have only installed the Cummins kit. It is bulletproof though. I have installed probabally about 75 - 100 of these and have never had one come back with a problem. Also the instructions are very straight forward. It does tell you to flash update the PCM as part of the installation but I can tell you you don't have to do that and everything works just fine.
  • bcippolabcippola Posts: 1
    Our 2001 Dodge Ram 2500 Cummins Diesel wouldnt start. Had it towed to local Dodge Dealer and we were quoted $300 to diagnos and $3000- $4000 to replace the main fuel pump and injector pump???? Can this be??


  • dasboot72dasboot72 Posts: 115
    Hi, look at some of my prior recent posts about the lift pump failing. You probabally don't need an Injection pump. You should probabally get an opinion from another dealer and $300.00 for diag is insane. For a diesel truck my dealer gets $99.00 for diag.
  • rcdmascorcdmasco Posts: 2
    I have a 1995 dodge diesel 5.9L the truck will start and idle when parked on level surface. Can drive for about 1 mile and seem to run out of fuel. I have to bleed the system to restart. Have changed the lift pump and cleaned the fuel tank and the problem still happens. ANY HELP!!
  • dasboot72dasboot72 Posts: 115
    Hi, you most likely, based on your description, have a pinhole in a fuel line. The one I have seen a few times is the tank to (original liftpump). The thing about it is you won't see any fuel leak, the hole is only large enough to suck air. There are some tests that would need to be done to verify, but if you wanted to change the fuel line from the tank to the old lift pump location, it probabally doesn't cause too much.
  • planbinplanbin Posts: 2
    edited March 2010
    About 2 weeks ago, on the freeway with cruise set at 60 mph. Cruise turns off pushed on accelerator nothing happen. Noticed Check Engine Light came on (For the first time)
    Tach was about 850 RPM .After about 10 seconds and pumping the accelerator petal
    took off again.I lost power 1 more time about 5 minutes later for a second or two.
    Made it back to the shop ,about 40 miles, no trouble. Had Friend check codes
    P2121 P2122. He reset. drove home about 35 miles no problem.
    Next morning drove about 200 yards Light comes on again loose throttle response for about 2 seconds then runs find rest of the day. Same codes P2121, P2122.
    Reset again. no problem for 3 or 4 days. Then leaving for work same thing happens about 1/4 mile from home this time. After several stops I notices Check Engine Light is Off. Later that day light comes on loose throttle response for a second or two. Then I try to set Cruise Control will not set. Cruise Light comes on it just will not Engage. Later that same day light goes off cruise works fine.

    Every day or two same thing happens light come on loose throttle response for a second or two, after a while light goes off.

    I've had truck since new 292,000 miles. Replaced Lift pump with in the tank unit about 1 Year ago. Any Ideals?
  • dasboot72dasboot72 Posts: 115
    Hi, P2121 is APP volts do not agree with idle signal & P2122 is Low volts at app sensor. There are 2 possible types of APP (accelerator pedal position) sensor types for your year truck. One is mounted in the engine compartment and linked to the throttle pedal via a cable. The other type is built into the Throttle pedal. These codes indicate either a faulty APP sensor, or wiring for the APP sensor. One kinda common area for a wiring issue that would effect the APP circuit is an engine ground strap that may come into contact with a wire harness. The strap is hooked up to the left rear of the cylinder head and runs to the body. Make sure it hasn't rubbed through into some wiring. With all the miles on your truck it would be perfectly reasonable for you to just have a bad APP sensor.
  • Thanks DASBOOT.. I have the pump on order and will install it myself.. I'll let you know how it turns out...
  • Truck starts and runs fine at an idle but when you try to accellerate it acts like the tps is bad. The truck throws 5 codes low voltage to the following: PCM, temp sensor, turbo boost, TPS and IAT. Please help! I do not want to start replacing very expensive parts that may not be bad.
  • dasboot72dasboot72 Posts: 115
    If you can give me the P code numbers I can maybe find a common circuit between the effected sensors. Let me know.
  • i just had to buy one for my 2002 dodge 2500 cummins, i found mine on ebay, picked it up for a little over $400 with shipping, its a mopar kit, it comes with directions also.
  • Dasboot; Today I was doing some additional investigations and found the following. When I turn off the o/d I can drive the truck up to 2625rpm and there is no hesitation.(2) after reading some other blogs I tried the cruse control; The cruse control will turn on but will not engage; with o/d on or off. the other thing I noticed that may or not be related is when I take off with the o/d off and accelerate to about 45mph the turn the o/d on it seems to do better.. I plan to remove the fuel tank and inspect the prefilter... Question; is there a way other than putting an ocilliscope on the alternator output to check for alternator RFI?...... Whats puzzling at this point is when the o/d off it seems to run fine.. Although I am only going 50mph the fuel consumption is higher at 2625 rpm.. One other thing. I have a super chip installed since 2002 and have had no problems with it.. Could this be a contributing factor? Thanks
  • Jfiggs22; I have an 01 Dodge 3500 with the 5.9 and trobleshooting the same problem. The forum has been helpful in directing me with the most common problems.. It appears that the alternator will produce high RFI (radio frequency interference) affecting the TPC. (2) my truck has the lift pump(factory) mounted under the hood just below the fuel filter and it may be going bad.. Not sure about the 02.. (3) the fuel lines up to the fuel pump may have worn a small pin hole in it causing the pump to momentarly lose prime.( Dasboot) has been helpful in this quandry... The other thing I have noticed with mine is if I turn the o/d off the truck seems to run fine.. This may point to the alternator issue. You may want to check yours. I am also going to drop my tank and check for any filter pluggage or gel in it that may contribute to the problem.. I will also make the in tank mod. that is recommended.. If there is a pin hole leak after the mod, because the line is pressurized from the tank it will show up... Hope this helps..
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