1991 4.3 will I hear the fuel pump engage?

Discussion in 'Chevy Truck Forum' started by Smokin1991, Dec 28, 2014.

  1. Smokin1991

    Smokin1991 Senior Member

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    Sure enough....I replace the master cylinder reserve, exhaust system, bearings, and now the truck won't start.

    At first I thought it was the damp, rainy days we had, as it turns over and cranks but will not fire. But two years ago I replaced the cap and rotor and that solved the damp issue.

    So today I get some starting fluid, spray into carb. Fires right up then stalls!

    Here comes my next question...when i turn the key to accessory, should I hear the fuel pump prime? All I hear is a small clunk, sounding like it is coming from under the hood. I hear it on my 1999 4.3 Astro.

    Things replaced over the last two years:
    coolant sensor
    oil pressure sensor
    cap-rotor-plugs-wires


    Thanks!
     
  2. cjpayne

    cjpayne Senior Member

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    Have a friend turn the switch to "on", not "accessory", while your under the tank. You should hear it prime.
     
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  3. Smokin1991

    Smokin1991 Senior Member

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    I am sorry, I mean "on" right before cranking.
     
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  4. MrMarty51

    MrMarty51 Full Member

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    Some of them pumps is mighty quiet, I have had to use a large screwing driver, stick the handle to My ear, the blade to the tank, then, have someone turn the key to the "RUN" only position, not the cranking position.
    Pump should run for about 3 to 5 seconds.
    If You are hearing a clunk noise from under the hood, the fuel pump relay is towards the R.H. side, bolted to the fire~wall, hold onto it, have someone turn the key to the run position, see if it klunks or klanks whan the key is turned.
    Disconnect tank harness, might be just forwards of the tank, see of klunk still persists. If not, and, You did`nt hear the feul pump run for the few seconds, then, remove the box, clean off top of tank and replace the pump and strainer sock.
     
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  5. cjpayne

    cjpayne Senior Member

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    I've never tried it but, you may be able to feel the pump vibration on the tank.
     
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  6. Smokin1991

    Smokin1991 Senior Member

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    If it does clunk, what then? That does seem like where the sound is coming from.
     
  7. chevychase

    chevychase Semi-Admin
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    Try this to test the pump ..run 12 volts to G terminal at adld scan port ...see if pump comes on ..just for a few seconds..if pump stuck might burn wires .
    You should here pump run ..for a few seconds with key on. The relay should click..when key turn on. Also check ecm fuse.
    click here
     
  8. Smokin1991

    Smokin1991 Senior Member

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    Fuse okay....truck is a shop in parking lot. Getting colder.....
     
  9. chevychase

    chevychase Semi-Admin
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    Do as advised by all brrr..the quick check at relay..or G at scan port will tell you if pump is good...unless a wire is broke..or lost ground at tank to frame..these rust bad...no ground no go.
     
  10. chevychase

    chevychase Semi-Admin
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    Can try this..if pump just quit..get a something like a board..tire tool thump on bottom of tank..while someone turns key on.
    Might get it to start this way..get it home to change..i have done this.
     

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