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HELP! 94 1500 running terrible once it's warmed up..

Discussion in 'Ram Trucks' started by gotsnow?, Oct 14, 2009.

  1. gotsnow?

    gotsnow? Senior Member
    Messages: 257

    Just bought a 94 dodge 1500 w/ the 360. Truck had set w/ out being used much at all for about a year and a half (i think just a few miles were put on it throughout the 1.5 years....). Test drive and driving home for the first 40 miles went fine, no problems. But then it started running rough and seemed to be loosing power when under a load (driving up hill) and it shakes a quite noticably off and on. I got it home and did the spark plugs, cap, rotor, new water pump and thermostat (due to a leak and the return hose to the radiator was really cool after driving it for a while). Now the truck runs fine when its cold but after it gets warmed up to normal operating temps it does all the above.... Runs rough, seems to have no power when driving up a hill or just accelerating hard and it back fire occasionally.

    What the heck is wrong with this thing???? :realmad:

    REAPER 2000 Club Member
    from 60050
    Messages: 2,228

    Did you do plug wires as well? Maybe one has a hairline crack that opens up more when warm and the wires get more pliable.

    EGR? PCV?

    I had a GMC that did the same exact thing when the fuel filter got dirty. That year Dodge I believe it is just a screen in the tank but you could disconnect the line before the engine and look at the quality of the gas coming out.

    If it looks fine hook up a pressure gauge and although it is a pain maybe gray tape it to the windshield and drive around looking at flow rate when cold -vs- warm.
  3. gotsnow?

    gotsnow? Senior Member
    Messages: 257

    did not try plug wires yet, I have heard they seldom go bad so I hadn't touched them yet... The fuel filter on the 94 is part of the fuel pump and only replaceable by changing the whole fuel pump, which is $179. I will look into the plug wires cause I suppose that could be part of the problem. Obviously it has something to do w/ the truck running at full operating temperature as the problem doesn't start till it has warmed up.
  4. deebo1133

    deebo1133 Member
    Messages: 40

    Could possibly be an o2 sensor...
  5. affekonig

    affekonig Senior Member
    Messages: 909

    Did you try googling it yet? I had an 02 with the 360 and it would do something weird like this every once in a while. It wasn't every time it warmed up, but I remember looking into it and finding some answers. Try googling "ram backfire" and I'll bet you come up with something. Good luck.
  6. Jack33

    Jack33 Junior Member
    from NH
    Messages: 22

    I suspect a bad coolent temp sensor. This is the sensor for the ECU, not the sender for the gauge.

    You can test to see if it is working by checking resistance across the 2 terminals when cold and hot. There should be a noticable difference between the 2 readings.
  7. Jack33

    Jack33 Junior Member
    from NH
    Messages: 22

    Possibly a bad EGR valve also. If I remember right that one is vacuum controlled. Pull the hose off the valve and see if it helps. You can see if it is working with a hand vacuum pump. Sometimes you can clean the carbon out to get it working again.
  8. gotsnow?

    gotsnow? Senior Member
    Messages: 257

    Where can I locate this coolent temp sensor?? That sorta makes sense since it runs fine till it warms up to normal oper. temp.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,581

    When it is acting up is it running rich??? If so 99% sure of the coolant sensor too. As for the wires start the truck up at light and open the hood. Look for blue sparks or arcing.
  10. Jack33

    Jack33 Junior Member
    from NH
    Messages: 22

    It is next to the thermostat. There are two of them, 1 for the gauge and one for the ECU. You want the one with 2 prongs in it.
  11. gotsnow?

    gotsnow? Senior Member
    Messages: 257

    Wires have been replaced, still ran bad. Will look into the coolant sensor, I'm not sure if it's running rich or not though.
  12. AC2717

    AC2717 Senior Member
    Messages: 669

    I Have an 02 that did that, turned out it was the engine computer Brain taking wrong readings, covered until 80,000miles Dodge had to replace for free.
  13. gotsnow?

    gotsnow? Senior Member
    Messages: 257

    :nod: Well it's finally fixed and running good! Can you believe this, it was the fuel pump..... I had a mechanic friend of mine take a look at it, he checked the fuel pump while driving it around and found when it ran like crap, sputtered and backfired it was only running at 5 lbs of pressure. So we replaced it, still ran a little rough, so adjusted the distrubiter.... and all is well again!

    Thanks to everyone for their ideas and thoughts!