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bill
bill, dodge master tech
Category: Dodge
Satisfied Customers: 1563
Experience:  25 years with dodge drivability and electrical expert
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93 dakota, 3.9, throttle body, 2wd, auto trans, air cond.

Customer Question

'93 dakota, 3.9, throttle body, 2wd, auto trans, air cond. (still works fine), 233,000 mi. Runs great, doesn't burn or leak oil. After 7 to 10 miles on a hot summer HUMID day it starts to buck, backfire, and finally stalls. Wait an hour and its running great again. No trouble fall, winter or spring. Just problems on HUMID summer days. Thinking about sending it to AZ. Over the last three years, I have done tuneups, plugs, wires, dist cap, coil, battery cable connectors, computer, and most recently a fuel pump. It starts fine in the humidity, but stalls out at about 7 to 10 miles. I believe it is only a condition that occurs when it's running since it always starts and runs long enough to get me to the boonies or the middle of the interstate.
Submitted: 1 year ago.
Category: Dodge
Expert:  bill replied 1 year ago.
have you pulled codes as of yet?do you know how to pull codes on the older dodge systems?just because there is no check engine light (the PRE OBD2 vehicles can, and often do, set codes without any check engine light ever being illuminated
Customer: replied 1 year ago.
Not recenly, but I recall it had nothing to do with the problem or did not resolve it. I could pull them again. Will have to refresh my memory. Key on and off 3 times, count the blinks, mark down number of blinks between pauses???
Customer: replied 1 year ago.
May take a while, buy I'll do it.
Expert:  bill replied 1 year ago.
correct if the truck is dying and it is sensor related I.E. a failed pick up coil it WILL set a fault, when the truck is dead have you done any BASIC diagnosis, like checking for fuel, spark, injector pulse, attempting to pull codes?here is a link to the procedure and codes http://www.allpar.com/fix/80s-codes.html
Customer: replied 1 year ago.
Just a 12. Battery disconnect.
Expert:  bill replied 1 year ago.
how long has it been since the truck died, have you had a dead battery or disconnected the battery since the truck has died,and as I asked above have you done any basic diagnostics WHEN it's dead?
Customer: replied 1 year ago.
Battery disconnect was done before stall. That is when I replaced the corroded cables connectors. Stall ocurred on highway where I could not trouble shoot, and was towed home. It is almost impossible to diagnose because by the time you are able to do so it's running again. Started up right away after reaching home. More than an hour and it starts up fine. Something has time to dry out after the stall and it runs again. I thought it was a carburator freeze and then it occurred to me that it only has a throttle body.
Expert:  bill replied 1 year ago.
which engine is in the truck? v8 or v6, and 1 BIG thing to do when it's dead is try and pull codes, there is a LOT you can do when it's dead assuming you can pull over to a safe place.1) attempt to pull codes, if the check engine light does not respond then it indicates the computer is "down" this could be a loss of power to it ground to it or a failed sensor that pulls down the communication to the computer, since you already have a code 12 battery disconnect in memory a EASY test to see if the computer is going down is to set another code say a code 22 coolant sensor circuit code by unplugging the coolant sensor, DO NOT erase this code, after a key cycle the check engine light will go out and the computer will keep this code in memory for 255 starts and when the truck dies attempt to pull the codes either then or after it is running again if the code you intentionally set is still there assume the computer is NOT going down if it is GONE and only the code 12 remains assume the computer is crashing and look at the powers and grounds feeding it AND the crank position sensor loss of any of these will cause the computer to go down and erase the memory2) check for spark a spark tester is CHEAP at most auto parts stores and can be placed in line with a spark plug to see if there is any spark.3) check for fuel this engine has a test port that can be pressed to see if there is any fuel in the rail under pressure, you should have around 45 to 50 psi fuel pressure assuming it's a magnum multiport injected engine BUT it should run and idle with as little as 10. without knowing what is being lost you are wasting money and time throwing parts at it.
Expert:  bill replied 1 year ago.
also you can take a garden hose and wet the engine bay and see if the engine dies
Customer: replied 1 year ago.
In my original question, I gave you all the specs for the vehicle. It's a ' 93, 3.9, throttle body, fuel injected engine. With***** air conditioning that still works fine, and automatic transmission.
Customer: replied 1 year ago.
The garden hose is a good idea, but I discounted that, because I have no problems in the rain. This has got to be something due to humidity and when the engine has run for a while.
Expert:  bill replied 1 year ago.
there is NO magic diagnosis or fix here I need to know what is being lost before anyone can assist further, I have given you 3 scenarios and you must follow them to determine what is missing when the truck dies, otherwise you are guessing and that's very expensive
Customer: replied 1 year ago.
Thank you very much. You gave me a test on the computer that I hadn't thought about and maybe one on the fuel pump. I'm pretty clever when it comes to auto repair, but this one is stumping me. I hate to give up on this one and spend on new, since it otherwise runs great. Thanks again for your help. I think it was worth it.Guy
Expert:  bill replied 1 year ago.
these older systems were super simple, I cut my teeth on the earliest efi systems we had and like today's systems you still need fuel and spark to make the engine run, if all else fails I would look at he distributor puck up coil and/or (if it's a magnum engine) the crank sensor either of these were very common failures and will cause the truck to die