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'94 Dodge idles really bad

Discussion in 'Ram Trucks' started by whwright, Aug 21, 2003.

  1. whwright

    whwright Member
    Messages: 39

    Hey guys. I'm usually working on a Chevy, but today I'm working on my father-in-law's Dodge.

    It's a '94 Dodge 1-ton van with a 318. It has 138,000 miles on it. Yeah, I know it's underpowered, but he's old.

    For about three months the van has been idling really bad. About three weeks ago I decided to do something about it. I first did the tune-up thing: plugs, wires, cap, rotor. The plugs were BLACK, and two plug wires fell apart as I removed them. It runs better, but still not too good. Then I ran a bottle of injector cleaner through it, but it didn't seem to help very much. It's at a point where it will at least sit and idle at a stop light, but there's still a long way to go.

    When he dropped my kids off tonight (he took them for ice cream), we were talking while he left the van idling in gear. I noticed that each time the engine stumbled, I could hear what seemed to be the fuel pump struggling. When I got closer to the fuel filler, I could hear a steady "buzzing" of the fuel pump, and when the engine stumbled the "buzz" got momentarily louder.

    Am I on to something? As far as I know, the fuel pump and filter are original to the van. Wouldn't the computer give us a "check engine" light if the fuel pressure was low due to a clogged filter or weak fuel pump?

    Thanks for the help.

  2. Plow Dak

    Plow Dak Member
    from Maine
    Messages: 48

    Hi Wayne
    Usually an idle problem with these Dodges can be traced to a very dirty Throttle body and or AIS Moror circuit. Pop off the air cleaner and open the throttle. Run your finger down along the bore and feel for a ridge. What happens is a buildup of crud along the closed area of the butterfies. It makes the AIS motor keep bumping up untill it's at it's count limit. It can't open anymore. THe engine should flair when it's first started.
    Take a toothbrush and some Wynn's cleaner and scrubb the bore and blades clean. If you don't have access to a scan tool to reset the AIS memory then try disconnecting the batery for 5 min.
    some PCM's will reset, some won't. Your first start will be a little hard. After you get it up to temp, shut it off and restart. If you get a flair on startup your AIS motor is working. Once the motor is reset to a more normal setting it will help keep your engine idleing.
    A check engine light won't come on for low fuel pressure. No sensor input. It will throw a light for a Mulit- cyl. misfire for a lean condition or a 02 sensor locked.
    The fuel pump noise change could be because of voltage varience due to it almost stalling and the Alternator is playing games with it.
    This is only one suggestion.
    EGR valves, broken hoses, etc can cause lots of simular problems. I'm assuming you checked for that.
    Happy cleaning..
  3. griffithtlc

    griffithtlc Senior Member
    Messages: 213

    I have to back up Mike's reply on this. We have a 97 w/ 318, and it used to do that, it would kill on you at some stop signs (bad when you aren't expecting it and the power steering cuts out when you are turning next to a car :D ). If you would rev it in park, and let off the throttle quickly, it would drop to about 400 RPMs, and would either die, or slowly stabilize. We got it cleaned, and it was all better.:D
  4. wyldman

    wyldman Member
    Messages: 3,265

    I think Mike is right on this one too.

    Only thing I will add is use a product called "Tune-up Cleaner" by Motorcraft,available at local Ford dealers.It works 10 times better than any other cleaner,so you don't even need to scrub the throttle body much.

    Use some to clean the TB with the engine off.Then start the engine,and run it till it gets hot.Spray the rest of the can down the TB with the engine running,and use a little bit of throttle to keep it running.As the can runs out,let the engine stall,or shut it off.Let it sit for 30 mins,then take it out,and drive the snot out of it for a 10 mins or so.You will see all the crap coming out the tailpipe.After you do this,then perform your idle relearn procedure.

    Like Mike said,the fuel pump noise is due to voltage variations,and pressure fluctuation,and is usually considered normal.
  5. whwright

    whwright Member
    Messages: 39

    Thanks for the information guys. I would have replaced the fuel pump for possibly nothing.

    I'll let you know how it turns out.

  6. whwright

    whwright Member
    Messages: 39

    Hey again guys. I know it's been almost a month, but I just managed to wrestle the van back from my father-in-law this afternoon.

    The ridge of carbon in the throttle body was exactly as you described. It's interesting how the throttle body was shiny clean, except for the ring right around the butterflies. The butterflies themselves were pretty black too. After a good cleaning the van idles nicely and will sit in gear without having to feather the pedal. With any luck we've got the thing running good again.

    Getting my father-in-law to drive the snot out of anything is pretty interesting. (Imagine saying "I said give it LOTS OF GAS" about a hundred times.)

    I was mistaken about the engine size. It turns out that it's a 5.9 liter, which I believe is a 360. But your fix still worked.

    Thanks for the help!


    Note to Wyldman: the Chevy truck is still running perfectly, and I haven't had to touch it since my son started driving it. Cool!
  7. wyldman

    wyldman Member
    Messages: 3,265

    Glad to hear it worked Wayne.Isn't it nice when the fix is so simple ?
  8. Plow Dak

    Plow Dak Member
    from Maine
    Messages: 48

    Alright Wayne
    Way to go
    Happy for ya

    Once in a while you get lucky.