1991 Chevrolet Silverado Idle problems

Tiny
BABE THE BLUE OX
  • MEMBER
  • 1991 CHEVROLET SILVERADO
  • 5.7L
  • V8
Ive got a 91 silverado 350 with some idle problems. When you first start it u need to give it throttle for a few seconds to keep er running and when she does stay running she idles really low, then if your not giving her gas and you cut the wheel shell cut out. Any ideas? Its got a new power steering pump and a nee belt new battery too im not sure if that would make any difference. Any suggestions as to what I can do would be greatly appreciated!
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Friday, July 17th, 2015 AT 4:14 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,014 POSTS
Have you checked for engine vacuum leaks? Have you checked the idle air control valve (IAC)? The IAC is responsible for maintaining engine idle speed.
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Friday, July 17th, 2015 AT 8:40 PM
Tiny
BABE THE BLUE OX
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  • 6 POSTS
Ill have to check those out when I get the time, new to carb motors so im just looking for some starting points
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Saturday, July 18th, 2015 AT 9:26 AM
Tiny
JACOBANDNICKOLAS
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A 91 shouldn't have a carb. Are you sure?
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Sunday, July 19th, 2015 AT 6:03 PM
Tiny
BABE THE BLUE OX
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  • 6 POSTS
Quite sure got a great big air filter circle air filter on top the motor.
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Sunday, July 19th, 2015 AT 6:06 PM
Tiny
BABE THE BLUE OX
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Only had the truck a couple days so I dont know a whole lot about it, ill send ya a picture in a hour or so when I get home
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Sunday, July 19th, 2015 AT 6:10 PM
Tiny
JACOBANDNICKOLAS
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I'll look for the pic. Chances are you have throttle body injection, which can look like a carb and have the round air filter housing.
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Sunday, July 19th, 2015 AT 6:11 PM
Tiny
JACOBANDNICKOLAS
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I attached a pic of the TBI system on a 91 GM 5.7L. Let me know if this is what you have.
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Sunday, July 19th, 2015 AT 6:13 PM
Tiny
BABE THE BLUE OX
  • MEMBER
  • 6 POSTS
Yeah I would say thats what it is, like I said ive never had a carburated motor before so its beyond my knowledge.
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Sunday, July 19th, 2015 AT 6:14 PM
Tiny
BABE THE BLUE OX
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  • 6 POSTS
Thats right under the filter right?
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Sunday, July 19th, 2015 AT 6:15 PM
Tiny
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Yes, it's under the air filter housing. The two ports have injectors above them which spray fuel into the intake. This design is know as Throttle Body Injection (TBI).
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Sunday, July 19th, 2015 AT 6:22 PM

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