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Posted on Dec 24, 2013
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I have a 1986 GMC 1500 with a 5.0 and stock rochester carb. The truck will start but you must keep gassing it as it won't idle. It kicks off every time. Any suggestions on how to fix this cold natured

It has new plugs, wire distributor and fresh oil and gas. I have sprayed cleaner in the carbs and added a fuel system cleaner.

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montehammons

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  • GMC Master 5,531 Answers
  • Posted on Dec 24, 2013
montehammons
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Joined: Sep 14, 2011
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Fast idle speed screw, works off the fast idle cam which the choke adjustment sets, it works together by linkages. This is the raised idle speed setting you need to keep a cold engine running. First you set the idle speed by the idle speed screw with engine at normal operating temperature. Then you set the linkage up so the cam is on a raised step, throttle will be held on that raised step. then you can turn the idle speed screw to get idle at about 1500-1800 rpm. Now when you start engine cold, choke will set the fast idle cam on that raised step- when engine starts and runs it should be running at your fast idle setting. That's how it supposed to work, you just have to get everything adjusted right. I hate carburetors, they never stay adjusted right. Considering their complexity and small mechanical parts, no wonder.

5 Related Answers

Anonymous

  • 39 Answers
  • Posted on Aug 18, 2009

SOURCE: Fuel system

fuel pump? carb? or throttle body? if injected the fuel rail should have a test point it will look kinda like a tire valve may have 15-40 psi under it auto places like auto zone and others rent kits for testing turn key forward listen to hear the pump in tank if injected push the valve in with a pen possible but becareful not to get in the way of gas use rag to catch it if nothing comes out most likely fuel pump but you will have to try to start the vehicle before attempting this raw check as line pressure falls off naturely in 10 min or so

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Anonymous

  • 92 Answers
  • Posted on Sep 20, 2009

SOURCE: 1994 Yukon running rich and flooding

Fuel pump circuit (low voltage)
Try replacing the fuel pump relay or testing it if you have the manual.

Lee Seliga

  • 239 Answers
  • Posted on Nov 08, 2009

SOURCE: I have a 1985 GMC C1500 Pickup. It has a Chevy

Your carb needs rebuilt, the float is to high or just really crapped up inside. You are dumping fuel in. Lee

Jonah Oneal

  • 14092 Answers
  • Posted on Dec 30, 2009

SOURCE: 96 gmc vortec will not start

I AM LOOKING AT TIMING ISSUES OR INTAKE MANIFOLD LEAK.OR EGR VALVE STUCK OPEN.

lesabre1972

Mike Watson

  • 474 Answers
  • Posted on Jan 31, 2010

SOURCE: My 1993 GMC Sierra wont start it will turn over

sounds like you have a bad fuel pump which is in the fuel tank

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