Choking out

Tiny
JACKNUT
  • MEMBER
  • 1995 CHEVROLET 3500
  • 5.7L
  • V8
  • 2WD
  • MANUAL
  • 184,000 MILES
I start it cold it idles seems like choke is on a little but it's a TBI. Drive about three miles to gas station shut it off got gas. Went to start it turned over for about thirty seconds, started hard, then cloud of black smoke before it cleared out. Ran okay after that. EGR? I used throttle body off the engine I pulled out. If ran great on other motor other motor seemed more responsive with throttle than this one. Any idea? Has new plug, wires, cap and rotor.
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Sunday, April 21st, 2019 AT 4:16 AM

2 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,883 POSTS
Welcome back to 2CarPros.
That sounds a lot like the EVAP purge solenoid has failed open. When that happens the engine has a direct path to the vapor canister and the fuel tank vapor system. As you fill the tank some of the fuel vapor builds in the canister. When you start the engine it draws all that fuel vapor in and acts just like a stuck choke. Many times the engine wont start because it is essentially flooded with fuel. It's an easy part to change out. It looks like the image and is located on top of the engine just behind the thermostat housing. Remove the hoses and the electrical connector and then the valve. Reverse to install the replacement. I generally don't bother to test them because as they start to fail they can work fine for a week, then stick open again.
In proper operation it stays closed until the PCM sees certain signal inputs, then it opens to clean out the vapor canister. These, like the rear EVAP vent solenoid like to fail on GM trucks.
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Sunday, April 21st, 2019 AT 4:37 AM
Tiny
JACKNUT
  • MEMBER
  • 65 POSTS
  • 1995 CHEVROLET 3500
  • 5.7L
  • V8
  • 2WD
  • MANUAL
  • 184,000 MILES
I changed the temperature sensor beside the thermostat. Now it starts, but when driving it seems okay, if I open it up it will get going then sputter. Then when I stop turn off motor it won't start. I disconnect both injectors it starts and shuts off. I hook then back up it starts and runs. It's there a vacuum diagram some place? Maybe I have the EVAP lines wrong. I do not know.
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Monday, April 22nd, 2019 AT 2:10 PM (Merged)

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