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89 3500 dually problems

Discussion in 'Chevy Trucks' started by williamtii, Dec 12, 2011.

  1. williamtii

    williamtii Junior Member
    Messages: 4

    Hey guys I have an 89 dually 3500 with a 454 that I'm trying to get ready for duty and it's starting to drive me nuts. I'm hoping that you can help because it's getting costly pretty fast.

    The back story is that it's been sitting since last winter save for the October dump where it ran fine. The guy I picked it up from had the tranny rebuilt, plow put on, and put a silly stereo system in. (all with questional wiring.)

    It fires right up but idles high for 2 minutes before returning to normal. If you give it throttle it bogs and stalls. If you try to restart it you have to have the pedal to the floor and crank for 10 seconds.

    I am thinking it's a carb issue but perhaps a vacuum leak? It had chipmunks living in it so the air cleaner/ducting was filled with crap. I've been looking for a chewed hose but have found nothing save for a melted Engine Coolant Sensor connector on the pass. side. (I've got that coming in today.)

    Any ideas?

    Also the parking lights are always on. He said that it wasn't until the plow was put on that they started acting up.

    Any help is greatly appreciated, there is just so much going on with this rig.

    - Will
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,742

    Sounds like a carb issue. Choke, and maybe running rich. What kinda plow?
  3. williamtii

    williamtii Junior Member
    Messages: 4

    Im thinking it's a carb issue as well but it ran so well over the Halloween storm. And that was with all the mouse crap in it! Carbs are still pretty foreign to me, Im better with fuel injection but I'll give it a shot.

    Plow is a Boss Power V a year and a half old. He said it was good for a month or so then they wouldn't turn off. I have to disconnect the battery every time.
  4. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,742

    Maybe it got something in it, and it finally worked its way into the carb. Me and carbs dont mix either lol.
  5. adksnowo

    adksnowo Senior Member
    Messages: 370

    Is it TBI or carb? The coolant temp. sensor is important b/c the engine runs initially when cold in "open loop mode" then runs in "closed loop" mode with information from the sensors upon engine warm up. I thought an '89 would be throttle body injection unless someone swapped a carb in. The TBI engines didn't make a ton of power but were pretty dependable and normally ran pretty well with a little maintenance.
  6. williamtii

    williamtii Junior Member
    Messages: 4

    OK its TBI, sorry this thing might as well be rocket ship to me. I'm used to crappy old BMW's. As far as the sensor goes, I thought it was a coolant temp sensor but two parts stores dug it up as a coolant fan switch???
    Heres the little guy:

    Its a single wire that plugs into the head on the pass. side right above the #5 spark plug.

    But the connector that they list (mine is melted) is a two wire:

    And to make things worse, why is there a coolant fan switch at all? Its got a fan clutch! The A/C condenser fan switch is totally different.

    If it is a coolant fan switch, would this be the issue? $67 is pretty steep.

    Please tell me Im just an idiot, this thing is driving me nuts. I thought chevy's were supposed to be easy.

    On top of this now it wont start at all, sounds like it's not getting fuel. I can hear the fuel pump going so I've got reason to suspect the filter is gunked up from sitting so long.

    I'll be back over with a fuel pressure tester and a new filter to see, it's getting pretty late now.

    Thanks in Advance,
  7. adksnowo

    adksnowo Senior Member
    Messages: 370

    Couple things. I'm not an expert on the 454 BB Chevy. I did some work on Vortec 454 trucks as we had a couple of trucks at work with them. I do know small block TBI Chevy motors much better.

    There would be a coolant temp sensor for the fan b/c I know at least the later Vortecs had an auxiliary electric fan in front of the radiator core opposite the engine driven fan. I don't know if this sensor feeds info/parameters into the computer for running the engine as well. Don't know about the harness or 1 or 2 wire deal either. Just b/c the fuel pump makes noise does not mean it is working. You are on the right track with a fuel pressure gauge and getting the cruddy filter changed, especially if the thing sat with ethanol gas in it.

    If you have good fuel pressure you can take off the air cleaner and CAREFULLY use a mirror or something to see if there is gas squirting in both TBI barrels.

    Sounds like before when it would run then shut off it wasn't getting to closed loop, sometimes that is a sensor issue. Or maybe it is ignition. What do the plugs/coil/cap-rotor/wires look like?

    2 more things: Get a shop manual, there is a way to read codes on this by jumpering 2 terminals in the diagnostic plug under the dash, then a code will flash out sort of like morse code on the check engine light. The other thing is SweetK30 knows more about these trucks than I do...
  8. Silverstreak

    Silverstreak Senior Member
    Messages: 168

    tps sensor, or intake leak since its running high spray starting fluid all around the intake manifold gasket, esp. near the back, listen for changes in idle be careful

    have someone turn the key on while you watch the 2 injectors on the tb once you turn the key on they will give you a squirt of fuel, also make sure while cranking youre getting fuel in a spiral spray pattern

    no fuel at all = pickup on distributor is fried (had the button on the dist. cap break off once and the carbon got down in the pickup and ate it up)

    a crappy stream...or trickle...fuel restriction

    good spray, good spark, no firing ....water in your tank from sitting
    Last edited: Dec 14, 2011
  9. williamtii

    williamtii Junior Member
    Messages: 4

    Bad gas is the winner!!! Ten fresh gallons a new filter and shes running again. I didn't do a fuel pressure test before changing the filter as I would have liked (forgot the right fitting) but the pump is running at 12 PSI now. I also changed the coolant fan switch (melted) for $67 and the cheaper coolant sensor ($12).

    It runs like a champ now, no bogging when warm, no stalling. I think I'm starting to learn myself around this rig after going through a couple manuals (and this site).

    I also solved the parking light problem which was bad wiring at the switch. It still runs high idle for a few minutes before calming down but I can't find any leaks.

    The oil pressure is a little high, starts off almost at 60 psi before calming down to 45 when warm. The midpoint is 30psi I'm not sure what would cause this but it seems to run OK.

    Thanks for all the advice, you guys definitely kept me going!
  10. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,742

    High idle is completely normal . High oil psi same, normal . Not a big fan on the 12 psi fuel . Thought it was supposed to be higher ?
  11. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    tbi stock psi is 11-13 per book spec. but most systems checked can be as low as 9spi . so consider your self lucky at 12psi.

    and single wire temp sensor in head is for dash gauge. the 2 wire in the intake is for computer temp needs.

    and tbi's are known for sucking in the gasket between the tbi and intake manifold. = source for constant high idel that never goes down even when warm.