1995 Sierra 1500 TBI Starts then stalls

Discussion in 'Chevy Truck Forum' started by jkeleigh1, Nov 10, 2010.

  1. jkeleigh1

    jkeleigh1 Member

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    I have a 1995 gmc / chevy sierra c1500 5.7 v8 TBI.. The major problem I'm haveing right now is that I start her up and she starts.. the idle goes to about 1500 then surges for a moment then dies.... I have already replaced Coolant Temp Sensor, EGR valve, Plugs, Wires, Rotor, Distributor Cap, IAC, MAP Sensor, Fuel Pressure Regulator, Injector O-rings, Air Filter, Battery, Vacuum Lines, Oil and Filter..... I also did an Ohms check on the Fuel Relay and its sitting close to .79. I'm running out of ideas an money to keep going on this thing. Anyone with anything simlar? Thanks.
     
  2. 92chevywt

    92chevywt Full Member

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    id say check your throttle positioning sensor there is a way to test it u can look up on line. Also with that year you could disconnect it and fire it up and if that is the problem it should idle high but not die(note even though it may stay running after you disconnect it , it will hardly be drivable as the computer doesnt know how far the throttle is open)
     
  3. jkeleigh1

    jkeleigh1 Member

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    going to go try right now! I'll let you know what happens !
     
  4. jkeleigh1

    jkeleigh1 Member

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    Just tried the TPS test... the only change is that it died a bit quicker. Any other thoughts? Also, when it does start I can keep it started for a bit if I keep pumping the gas pedel. If I try and hold it at a constant RPM it dies.
     
  5. 92chevywt

    92chevywt Full Member

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    hmm try pouring some fuel down the throttle body then starting it and see if it idles til it is out of fuel(u can use starting fluid but too much will ruin the motor)
     
  6. chevychase

    chevychase Senior Moderator Staff Member

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    What i would put a bet on would be fuel pump , when you say it surges all of a sudden getting more air than fuel then dies. Do a pressure check on it and see what happens right before it dies. did you check fuel filter.
     
  7. jkeleigh1

    jkeleigh1 Member

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    I'll try the fuel trick in a bit.if it does work what does that tell me? bought a new TPS just to make sure that I just wasn't not noticing something. No change.. Fuel filter is new ... when I do the pressure check what should the pounds ideally be between? I siphoned some gas out where the fuel line hooks into the filter.... turned the key and the pump is giving a steady stream... easy enough to fill a five gallon jug. Didn't see the nipple by the TB to hook a pressure tester. neither could i find one anywhere down the fuel lines going to the tank. does this give any help as to what direction to take now... or would i still need to preform a pressure test somehow?
     
  8. 92chevywt

    92chevywt Full Member

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    u have to get a fitting adapter that hooks in line with the feed line from the pump
     
  9. Malibuz16

    Malibuz16 New Member

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    I have seen this twice...Once it was the plastic coupler between the oil pump and the driveshaft. The other time it was the oil pressure sending unit. Try to find a red wire with a connector near the battery this goes to the fuel pump relay and is used as a "prime" connector. This will bypass the fuel pump relay and supply 12volts to the pump. If you apply 12volts and the truck does not die then most likely it is the switch. The ECM will energize the pump for a few seconds to prime the system and after the engine starts the oil pressure switch completes the circuit to keep the pump running. This is done to prevent the pump from running with the engine off, in the event of a crash.
     
  10. jkeleigh1

    jkeleigh1 Member

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    thank you everyone for all your help.... checked the pressure .. was only getting 2 pounds !!! We replaced the fuel pump and shes up and running !! Thanks again!!
     

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