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89 tbi no start

Discussion in 'The Garage' started by 89newtome, Dec 14, 2005.

  1. 89newtome

    89newtome Registered Member

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    i am having problems with my 89. I went to start it the other day and it just cranked and no start. if i put throttle to the floor it would kind of spit and spudder. I checked all fueses and connectors all look good. I finnaly got it running by holding it to the floor and cranking until it started. It ran like **** for a few mins then the service engine light came on and it started running better just real rich. THe light went out and it started stumbling and died. the code I got was for temp sensor system. Would the temp sensor cause this? thanks for any info
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I would think it would start with a temp sensor failure but run bad.

    I would put a meter on the sensor and check the wires. There should be a range of values depending on the temp of the motor. I don't have my Factory manual handy hopefully somebody else does.

    Also check out the MAP sensor. I had a hose get old and crack causing a big vacuum leak and it ran horrible with that out.

    I would start with the basics and look for bad vacuum hoses and work your way up. My 88 had lots of cracked and hard hoses causes several run problems. They are just old and brittle.

    Verify the pump is running as well. Relay is on the fire wall over passengerside valve cover. Can check it for power. Ear to the tank while somebody cycles the key and hear if it fires off to build pressure.
     
  3. mouse

    mouse 1/2 ton status

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    Is the fuel pump running?
     
  4. mtrdrms

    mtrdrms 1/2 ton status

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    It sounds like a temp sensor to me. The plug usually gets corroded and rots away. happened on my 91 camaro.
     
  5. 3 on the tree

    3 on the tree 1/2 ton status

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    I think the temp sensor acts as a choke system. Gives extra fuel when cold starting, so yes it could cause the problem.
     
  6. Leper

    Leper 1/2 ton status

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    When the problem first happened, was the engine warm? If so, it IS the temp sensor. If it was cold it still could be. There is such a problem with the connectors for it that you can buy a new sensor from O'riellys, that comes with a new plug.
     
  7. virtualdemo

    virtualdemo Registered Member

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    First things first... When was the last time you changed the fuel filter or did a tune up? Also have you recently changed or done anything to the engine? Check your injector spray pattern, if it drips thats a bad injector.

    All of the TBI vehicles I had never ran bad due to having a bad temp sensor, goes into Limp mode and runs ok not great but idles fine. On initial start up all fuel/air calculations are run through the Ignition Control Module, underneath the dizzy cap. The ECM wont actually start controlling the fuel maps till the vehicle reaches 160 degrees or your exhaust temps reach 1400 degrees(i think thats the temp, someplace in that range).

    So, like mentioned above check for vacuum leaks, although with it running bad you wont easily be able to find it. On all my previous TBIs my problem always came from a weak fuel pump. They would prime and all but they were still weak. I had the same exact problems you mentioned above. Changed every sensor under the hood and it ended up being a weak pump. Now after a painful loss of $$$ I use the proper tools to check fuel pressure and I got an ALDL cable to see what the computer is actually doing when its running bad...

    Hope this helps...
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    That's just the problem with the temp sensor. If it's reading incorrectly, the engine will either try to go closed loop way too early, or never attempt to.

    Exhaust gas temp isn't monitored.
     
  9. fireplug

    fireplug 1/2 ton status

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    Short of the temp light I had the same probs a couple of weeks ago. Turned out to be a wire from the fuse box to fuel pump. I don't have any more details because I haven't seen the truck since it happened by buddy diagnosed it.
     
  10. 89newtome

    89newtome Registered Member

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    update on no start

    I changed the temp sensor for the comp. the thing fired right up and ran fine. Thanks for all the replies. I would never had guessed a temp sensor would cause it not to start. I checked wiring diagram in my buddies manual seems that the coolant temp sensor wiring goes through the throttle position sensor
     
  11. Leper

    Leper 1/2 ton status

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    This is why we love CK5!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
     

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